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  • 1.
    Almer, J.
    et al.
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Lienert, U.
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Peng, R.L.
    Linköping universitet.
    Schlauer, C.
    Linköping universitet.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Strain and texture analysis of coatings using high-energy x-rays2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 94, no 1, p. 697-702Article in journal (Refereed)
    Abstract [en]

    We investigate the internal strain and crystallographic orientation (texture) in physical-vapor deposited metal nitride coatings of TiN and CrN. A high-energy diffraction technique is presented that uses synchrotron x rays and an area detector, and which allows the strain and intensity distributions of multiple crystallographic planes to be measured by a single x-ray exposure. Unique texture states and nonlinear sin2 strain distributions are observed for all coatings investigated. Quantitative analysis indicates that existing micromechanical models can reasonably predict strain and corresponding stress for mixed-hkl reflections but are inadequate for fully describing measured data. Alternative mechanisms involving deposition-induced defects are proposed

  • 2.
    Almer, J
    et al.
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Håkansson, G
    Bodycote Värmebehandling AB.
    Microstructure and thermal stability of arc-evaporated Cr-C-N coatings2004In: Philosophical Magazine, ISSN 1478-6435, E-ISSN 1478-6443, Vol. 84, no 7, p. 611-630Article in journal (Refereed)
    Abstract [en]

    The role of C incorporation in the microstructure and thermal stability of arc-evaporated Cr-C-N coatings is explored via reactive growth in a mixed C2H4-N2 environment. C is found to react more readily than N at both the Cr cathode and the coating surfaces, so that a C2H4-to-N2 flow ratio of only 1% yields a C-to-N ratio of approximately 10% within the coatings. The as-deposited microstructures consist primarily of the δ-Cr(C, N) phase and possess high compressive residual stresses, which decrease with increasing C content. Post-deposition annealing up to 700°C results in depletion of lattice defects, and concomitant reductions in stress and coating hardness, together with phase transformations which suggest metastable phase formation during growth. Apparent activation energies for this lattice defect are found to be in the range expected for bulk diffusion of N and C (2.4-2.8 eV). The results suggest that inclusion of small amounts of C in this system offers the ability to reduce internal stresses while maintaining defect-related hardness increases, permitting growth of thicker and thus more wear-resistant coatings.

  • 3.
    Antti, Marta-Lena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Cheng, Y-B
    Monash University, Melbourne, VIC.
    Odén, Magnus
    Synthesis and phase development in the Ct-Al-N system2009In: Mechanical properties and processing of ceramic binary, ternary and composite systems: a collection of papers presented at the 32nd International Conference on Advanced Ceramics and Composites, January 27-February 1, 2008, Daytona Beach, Florida / [ed] Jonathan Salem; Greg Hilmas; William Fahrenholtz, Hoboken, NJ: John Wiley & Sons, 2009, p. 3-12Conference paper (Refereed)
    Abstract [en]

    The ternary nitride system Cr-Al-N has been investigated by sintering different powder compositions. The powder compositions belong to four groups, AIN- + Cr-powder (5 compositions between 20-90 molar% AlN), Al- + Cr 2N-powder (5 compositions between 15-80 molar% Cr2N), AlN-+ Cr2N-powder (50- and 90 molar% Cr2N) and Al- + Cr-powder. The powders were dry mixed and pressed into pellets by uniaxial pressing followed by cold isostatic pressing (ClP). Sintering took place in a graphite lined reaction bonding furnace under nitrogen atmosphere at three different temperatures, 1350°C, 1500°C and 1800°C and in an alumina tube furnace in order to avoid access to carbon. Holding times were varied, from 2 hours up to 72 hours. The phase development was evaluated by thermal analysis and XRD. CrAlN was formed at 1350°C but decomposed at higher temperatures. Both pure Al and Cr-powder were prone to react with carbon in the graphite furnace. Thermal analysis showed a sublimation of Cr2N at temperatures around 1050°C and nitridation of pure Al-powder between 680-750°C and of pure Cr-powder between 610-1080°C. Samples with pure Al-powder showed a very large expansion due to melting of aluminium in combination with nitridation. AIN was found to be more stable than Cr 2N at higher temperatures and longer holding times. The mixtures of Al-+Cr-powder produced an intermediate Al-Cr-phase.

  • 4.
    Escalera, Edwin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Antti, Marta-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Odén, Magnus
    Thermal treatment and phase formation in kaolinite and illite based clays from tropical regions of Bolivia2012In: 6th EEIGM International Conference Advanced Materials Research: 7th and 8th November, 2011 EEIGM, Nancy, France, Bristol: IOP Publishing Ltd , 2012Conference paper (Refereed)
    Abstract [en]

    The aim of this study was to compare the thermal behaviour of clays containing illite and kaolinite in various proportions. The clays contained small amounts of K and Fe, which act as fluxing agents. In order to investigate the phase formations during heating, the samples were examined in a differential scanning calorimeter at temperatures up to 1300°C. The thermal expansion of the samples was determined by dilatometer measurements from room temperature up to 1150°C. Phases were identified using x-ray diffraction and scanning electron microscopy. In all samples, most of the kaolinite was transformed into metakaolinite during heating up to 650°C, while illite remained unchanged up to 950°C. There was no influence of K and Fe on dehydroxylation. Metakaolinite formed at temperatures above 950°C leading to a Si-Al spinel. Furthermore, mullite was formed in the temperature interval 1050-1150°C. In this temperature range, the mechanism of mullite formation depended on the amount of K and Fe in the samples, changing the temperature of formation of mullite. It was observed by x-ray diffraction that most of the illite was transformed into a Si-Al spinel phase at 1050°C, and during further heating transformed into mullite. An increased amount of illite in the clays slightly decreased the melting temperature. The dilatometer measurements showed expansion and shrinkage for the dehydroxylation and spinel-phase formation, respectively.

  • 5.
    Escalera, Edwin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Ballem, Mohammed A.
    Nanostructured Materials, Department of Physics, Chemistry and Biology, Linköping University.
    Cordoba, José M.
    Nanostructured Materials, Department of Physics, Chemistry and Biology, Linköping University.
    Antti, Marta-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Odén, Magnus
    Synthesis of homogeneously dispersed cobalt nanoparticles in the pores of functionalized SBA-15 silica2012In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 221, p. 359-364Article in journal (Refereed)
    Abstract [en]

    Cobalt nanoparticles were prepared at room temperature by reducing cobalt sulfate heptahydrate with sodium borohydride using functionalized SBA-15 mesoporous silica as a hard template. It was found that both external and internal fuctionalization of silica walls play a crucial role on the infiltration and reaction of the reagents in the silica framework. Subsequent heat treatment of the impregnated silica at 500 °C in air or nitrogen atmospheres leads to growth of crystals of the deposited cobalt and formation of cobalt oxide and cobalt nanoparticles, respectively. Dissolution of the silica template by NaOH resulted in well dispersed Co and Co3O4 nanoparticles ranging in size between 2 and 4 nm. The functionalization of the silica was studied by FTIR, N2-physisorption, and thermogravimetric techniques and the obtained nanoparticles were characterized by XRD, TEM and EDX analysis.

  • 6.
    Escalera, Edwin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Garcia, Gustavo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Terán, R
    Chemistry Department, San Simon University.
    Tegman, Ragnar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Antti, Marta-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Odén, Magnus
    The production of porous brick material from diatomaceous earth and Brazil nut shell ash2015In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 98, p. 257-264Article in journal (Refereed)
    Abstract [en]

    Diatomaceous earth was mixed with Brazil nut shell ash (BNS ash) in different amounts between 0 and 30 wt% and sintered at temperatures between 750 and 950 °C. The BNS ash contains 33 wt% K2O and 11 wt% CaO mainly in carbonate form. The addition of BNS ash into the diatomaceous earth caused significant changes of the microstructure after sintering. The BNS ash addition produces lightweight porous bricks with acceptable strength at lower sintering temperature. The best combination of strength and porosity was achieved for a mixture of 10 wt% of BNS ash in the diatomaceous earth sintered at 850 °C. The achieved high porosity was 49%, density 1.06 g/cm3, thermal conductivity 0.20 W/(m K) and the compressive strength was 8.5 MPa.

  • 7.
    Escalera, Edwin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Tegman, Ragnar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Antti, Marta-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Odén, Magnus
    Linköpings universitet.
    High temperature phase evolution of Bolivian kaolinitic–illitic clays heated to 1250 °C2014In: Applied Clay Science, ISSN 0169-1317, E-ISSN 1872-9053, Vol. 101, p. 100-105Article in journal (Refereed)
    Abstract [en]

    The thermal behaviour of two types of clays collected from different locations in Bolivia has been studied. The clays contain kaolinite, illite, quartz and small amounts of microcline. The phase evolutions have been characterized from room temperature to 1250 °C. For both clays, kaolinite is completely transformed into metakaolinite when heated up to 650 °C. During further heating to 1050 °C, illite undergoes total dehydroxylation. Mullite is formed in the temperature interval of 1050–1150 °C and its formation rate is dependent on the amount of K and Fe present in the clays. The clay with higher amounts of K (3.2 mass %) and Fe (5.6 mass%) has an onset temperature for sintering at about 900 °C and an onset temperature for liquid formation at 1080 °C. This is about 50 °C lower onset temperature for sintering and 94 °C lower onset temperature for liquid formation when compared with the clay with lower amounts of K (2.3 mass %) and Fe (1.6 mass %).

  • 8.
    Gibmeister, Jens
    et al.
    Institute of Materials Technology, University of Kassel.
    Lin, R.
    Studsvik Neutron Research Laboatory.
    Odén, Magnus
    Scholtes, Berthold
    Institute of Materials Technology, University of Kassel.
    Residual stress distributions around clinched joints2002In: ECRS 6: proceedings of the 6th European Conference on Residual Stresses, Coimbra, Portugal, 10-12 July 2002 / [ed] A.M. Dias, Trans Tech Publications Inc., 2002, p. 617-622Conference paper (Refereed)
  • 9. Hedström, Peter
    et al.
    Almer, Jon
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Lienert, Ulrich
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Evolution of residual strains in metastable austenitic stainless steels and the accompanying strain induced martensitic transformation2006In: Residual Stresses VII: ECRS 7 ; proceedings of the 7th European Conference on Residual Stresses / [ed] Walter Reimers; Sabine Quander, Uetikon-Zuerich: Trans Tech Publications Inc., 2006, p. 821-826Conference paper (Refereed)
    Abstract [en]

    The deformation behavior of metastable austenitic stainless steel AISI 301, suffering different initial cold rolling reduction, has been investigated during uniaxial tensile loading. In situ highenergy x-ray diffraction was employed to characterize the residual strain evolution and the strain induced martensitic transformation. Moreover, the 3DXRD technique was employed to characterize the deformation behavior of individual austenite grains during elastic and early plastic deformation. The cold rolling reduction was found to induce compressive residual strains in the austenite along rolling direction and balancing tensile residual strains in the -martensite. The opposite residual strain state was found in the transverse direction. The residual strain states of five individual austenite grains in the bulk of a sample suffering 2% cold rolling reduction was found to be divergent. The difference among the grains, considering both the residual strains and the evolution of these, could not be solely explained by elastic and plastic anisotropy. The strain states of the five austenite grains are also a consequence of the local neighborhood. Introduction The metastable austenitic stainless steels partially transform from the soft and ductile austenite to the hard and brittle martensite during deformation. This deformation induced martensitic transformation provides a compos...

  • 10.
    Hedström, Peter
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Han, Tong-Seok
    Yonsei University, Seoul.
    Lienert, Ulrich
    Argonne National Laboratory, Argonne, IL.
    Almer, Jonathan
    Argonne National Laboratory, Argonne, IL.
    Odén, Magnus
    Load partitioning between single bulk grains in a two-phase duplex stainless steel during tensile loading2010In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 58, no 2, p. 734-744Article in journal (Refereed)
    Abstract [en]

    The lattice strain tensor evolution for single bulk grains of austenite and ferrite in a duplex stainless steel during tensile loading to 0.02 applied strain has been investigated using in situ high-energy X-ray measurements and finite-element modeling. Single-grain X-ray diffraction lattice strain data for the eight austenite and seven ferrite grains measured show a large variation of residual lattice strains, which evolves upon deformation to the point where some grains with comparable crystallographic orientations have lattice strains different by 1.5 × 10-3, corresponding to a stress of ≈300 MPa. The finite-element simulations of the 15 measured grains in three different spatial arrangements confirmed the complex deformation constraint and importance of local grain environment.

  • 11. Hedström, Peter
    et al.
    Lienert, Ulrich
    Argonne National Laboratory, Argonne, IL.
    Almer, Jon
    Argonne National Laboratory, Argonne, IL.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Elastic strain evolution and ε-martensite formation in individual austenite grains during in situ loading of a metastable stainless steel2008In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 62, no 2, p. 338-340Article in journal (Refereed)
    Abstract [en]

    The (hcp) ε-martensite formation and the elastic strain evolution of individual (fcc) austenite grains in metastable austenitic stainless steel AISI 301 has been investigated during in situ tensile loading up to 5% applied strain. The experiment was conducted using high-energy X-rays and the 3DXRD technique, enabling studies of individual grains embedded in the bulk of the steel. Out of the 47 probed austenite grains, one could be coupled with the formation of ε-martensite, using the reported orientation relationship between the two phases. The formation of ε-martensite occurred in the austenite grain with the highest Schmid factor for the active {111}b12¯1N slip system.

  • 12.
    Hedström, Peter
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Lienert, Ulrich
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Almer, Jon
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Stepwise transformation behavior of the strain-induced martensitic transformation in a metastable stainless steel2007In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 56, no 3, p. 213-216Article in journal (Refereed)
    Abstract [en]

    In situ high-energy X-ray diffraction during tensile loading has been used to investigate the evolution of lattice strains and the accompanying strain-induced martensitic transformation in cold-rolled sheets of a metastable stainless steel. At high applied strains the transformation to α-martensite occurs in stepwise bursts. These stepwise transformation events are correlated with stepwise increased lattice strains and peak broadening in the austenite phase. The stepwise transformation arises from growth of α-martensite embryos by autocatalytic transformation.

  • 13. Hedström, Peter
    et al.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Almer, J.
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Lienert, U.
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Bernier, J.
    Lawrence Livermore National Laboratory.
    Terner, Mark
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Load partitioning and strain-induced martensite formation during tensile loading of a metastable austenitic stainless steel2009In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 40, no 5, p. 1039-1048Article in journal (Refereed)
    Abstract [en]

    In-situ high-energy X-ray diffraction and material modeling are used to investigate the strain-rate dependence of the strain-induced martensitic transformation and the stress partitioning between austenite and α′ martensite in a metastable austenitic stainless steel during tensile loading. Moderate changes of the strain rate alter the strain-induced martensitic transformation, with a significantly lower α′ martensite fraction observed at fracture for a strain rate of 10-2 s-1, as compared to 10-3 s-1. This strain-rate sensitivity is attributed to the adiabatic heating of the samples and is found to be well predicted by the combination of an extended Olson-Cohen strain-induced martensite model and finite-element simulations for the evolving temperature distribution in the samples. In addition, the strain-rate sensitivity affects the deformation behavior of the steel. The α′ martensite transformation at high strains provides local strengthening and extends the time to neck formation. This reinforcement is witnessed by a load transfer from austenite to α′ martensite during loading.

  • 14. Hedström, Peter
    et al.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Stress state and strain rate dependence of the strain-induced martensitic transformation in a metastable austenitic stainless steel2007In: Fundamentals of Martensite and Bainite towards Future Steels with High Performance: Challenges for Strength, Toughness, and Ductility : The 1st International Symposium on Steel Science, Kyoto, May 16 - 19, 2007 / [ed] Tadashi Furuhara; Kaneaki Tsuzaki, Tokyo: The Iron and Steel Institute of Japan , 2007, p. 171-174Conference paper (Refereed)
    Abstract [en]

    The strain-induced martensitic transformation in a metastable austenitic stainless steel is investigated by high-energy x-ray diffraction and material modeling. Two different deformation modes are used (cold rolling and uniaxial tensile loading) and the effect on the strain-induced martensitic transformation behavior is investigated. Moreover, three different strain rates during the uniaxial tensile loading are evaluated. The results show a sigmoidal transformation behavior of the strain-induced martensite in respect to true strain, for tensile loading. The effect of different strain rates is also clearly seen and it alters both the amount of transformed martensite and the transformation behavior. The martensite transformation is drastically decreased already at moderate strain rates such as 10-2 s-1, due to adiabatic heating of the sample. The material model used gives an accurate prediction of the strain-induced martensitic transformation behavior during tensile loading. This is valuable for further implementation of the current material model in industrial forming mulations of real components.

  • 15. Hedström, Peter
    et al.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The use of high energy SAXS/WAXS for structural characterization of stainless steels2005In: Stainless steel world 2005: [Stainless Steel World 2005 Conference & Expo, Maastricht, the Netherlands, 8 - 10 November 2005] ; conference papers, Zutphen: KCI Publ., , 2005Conference paper (Refereed)
  • 16.
    Hultman, Lars
    et al.
    Department of Physics, Chemistry and Biology (IFM), Linköping University.
    Bareno, Javier
    Frederick Seitz Materials Research Laboratory, Materials Science Department, University of Illinois at Urbana-Champaign.
    Flink, Axel
    Department of Physics, Chemistry and Biology (IFM), Linköping University.
    Söderberg, Hans
    Larsson, Karin
    Department of Physics, Chemistry and Biology (IFM), Linköping University.
    Petrova, Vania
    University of Illinois at Urbana-Champaign.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Greene, J.E.
    Frederick Seitz Materials Research Laboratory, Materials Science Department, University of Illinois at Urbana-Champaign.
    Petrov, Ivan
    Frederick Seitz Materials Research Laboratory, Materials Science Department, University of Illinois at Urbana-Champaign.
    Interface structure in superhard TiN-SiN nanolaminates and nanocomposites: film growth experiments and ab initio calculations2007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75Article in journal (Refereed)
    Abstract [en]

    Nanostructured materials-the subject of much of contemporary materials research-are defined by internal interfaces, the nature of which is largely unknown. Yet, the interfaces determine the properties of nanocomposites and nanolaminates. An example is nanocomposites with extreme hardness70-90 GPa, which is of the order of, or higher than, diamond. The Ti-Si-N system, in particular, is attracting attention for the synthesis of such superhard materials. In this case, the nanocomposite structure consists of TiN nanocrystallites encapsulated in a fully percolated SiNx "tissue phase" (1 to 2 monolayers thick) that is assumed to be amorphous. Here, we show that the interfacial tissue phase can be crystalline, and even epitaxial with complex surface reconstructions. Using in situ structural analyses combined with ab initio calculations, we find that SiNx layers grow epitaxially, giving rise to strong interfacial bonding, on both TiN(001) and TiN(111) surfaces. In addition, TiN overlayers grow epitaxially on SiNx/TiN(001) bilayers in nanolaminate structures. These results provide insight into the development of design rules for new nanostructured materials.

  • 17.
    Hörling, A
    et al.
    Linköping universitet.
    Hultman, L.
    Linköping universitet.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Sjölén, J.
    SECO Tools, Fagersta.
    Karlsson, L.
    SECO Tools, Fagersta.
    Mechanical properties and machining performance of Ti1-x AlxN-coated cutting tools2005In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 191, no 2-3, p. 384-392Article in journal (Refereed)
    Abstract [en]

    The mechanical properties and machining performance of Ti1−xAlxN-coated cutting tools have been investigated. Processing by arc evaporation using cathodes with a range of compositions was performed to obtain coatings with compositions x=0, x=0.25, x=0.33, x=0.50, x=0.66 and x=0.74. As-deposited coatings with x≤0.66 had metastable cubic structures, whereas x=0.74 yielded two-phase coatings consisting of cubic and hexagonal structures. The as-deposited and isothermally annealed coatings were characterised by nanoindentation, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Cutting tests revealing tool wear mechanisms were also performed. Results show that the Al content, x, promotes a (200) preferred crystallographic orientation and has a large influence on the hardness of as-deposited coatings. The high hardness (37 GPa) and texture of the as-deposited Ti1−xAlxN coatings are retained for annealing temperatures up to 950 °C, which indicates a superior stability of this system compared to TiN and Ti(C,N) coatings. We propose that competing mechanisms are responsible for the effectively constant hardness: softening by residual stress relaxation through lattice defect annihilation is balanced by hardening from formation of a coherent nanocomposite structure of c-TiN and c-AlN domains by spinodal decomposition. This example of secondary-phase transformation (age-) hardening is proposed as a new route for advanced surface engineering, and for the development of future generation hard coatings.

  • 18.
    Johansson, Johan
    et al.
    Division of Engineering Materials, Department of Mechanical Engineering, Linköping University.
    Odén, Magnus
    Micro- and macrostress evolution in a duplex stainless steel during uniaxial loading2000In: ECRS 5: proceedings of the fifth European Conference on Residual Stresses held September, 28-30, 1999 in Delft-Noordwijkerhout, The Netherlands / [ed] Amarante Böttger; Rob Delhez; Eric Mittemeijer, 2000, p. 603-608Conference paper (Refereed)
  • 19. Kero, Ida
    et al.
    Antti, Marta-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Odén, Magnus
    Linköpings universitet.
    Preparation and firing of a TiC/Si powder mixture2009In: 5th International EEIGM/AMASE/FORGEMAT Conference on Advanced Materials Research, Bristol: IOP Publishing Ltd , 2009Conference paper (Refereed)
    Abstract [en]

    This paper describes how the preparation and heat treatment of TiC/Si powders influences the phase reactions during firing. The powders are prepared by milling and some effects of powder preparation are discussed. A solid state displacement reaction according to: 3TiC + 2Si → Ti3SiC2 + SiC is a priori expected to take place during heat treatment. The firing procedure is investigated with respect to the effect of heat treatment time and temperature on the phases produced, especially Ti3SiC2. Samples were heat treated in a graphite lined furnace. Heat treated samples are analysed by x-ray diffraction, scanning electron microscope and energy dispersive spectroscopy. Ti3SiC2, TiC and SiC are dominant in the final products. The highest amount of Ti3SiC2 is achieved for short holding times (2-4 hours) at high temperatures (1350-1400°C). Ti3SiC2 appears to decompose at elevated temperatures or extended times, through a Ti3SiC2 → TiC + Si(g) type reaction. The activation energy of Ti3SiC2 phase formation is determined to be 289 kJ/mol, using the Mehl-Avrami-Johnson model.

  • 20. Kero, Ida
    et al.
    Antti, Marta-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Odén, Magnus
    Linköpings universitet.
    Synthesis of Ti3SiC2 by reaction of TiC and Si powders2009In: Mechanical properties and processing of ceramic binary, ternary and composite systems: a collection of papers presented at the 32nd International Conference on Advanced Ceramics and Composites, January 27-February 1, 2008, Daytona Beach, Florida / [ed] Jonathan Salem; Greg Hilmas; William Fahrenholtz, Hoboken, NJ: John Wiley & Sons, 2009, p. 21-30Conference paper (Refereed)
    Abstract [en]

    The MAX phase Ti3SiC2 has been synthesized from starting powder mixtures which do not include pure titanium. The presence of pure titanium in a powder is problematic because of its oxidizing, and in the form of a finely divided powder, explosive nature. The aim of this study was to evaluate the synthesis of bulk polycrystalline samples of Ti3SiC2 from a starting powder mixture which is more suited for large scale production. Titanium silicon carbide MAX phase was synthesized by pressureless sintering of ball milled TiC and Si powders of six different compositions. The sintering reactions were evaluated in situ by dilatometer analysis under flowing argon gas. The as-sintered samples were evaluated using mainly x-ray diffraction (XRD) analysis. This study showed that titanium carbide, silicon carbide and titanium disilicide were present as intermediate or secondary phases in the samples.Our results indicate that TiSi2 is an intermediate phase to the formation of Ti3SiC2 when excess Si is present. The excess of silicon also proved beneficial for the synthesis of the MAX phase and there is a Si content which is optimal with respect to the maximum MAX phase content of the final product. The Ti3SiC2 was found to decompose into TiC and gaseous Si at high temperatures.

  • 21.
    Kero, Ida
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Antti, Marta-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Odén, Magnus
    Ti3SiC2 Synthesis by Powder Metallurgical Methods2007In: European School of Materials Science and Engineering, fourth research conference: preceedings of the fourth meeting of the European School of Materials Sciencie and Engineering / [ed] Marc Anglada, Barcelona: CPDA-ETSEIB , 2007Conference paper (Refereed)
    Abstract [en]

    Titanium silicon carbide MAX phase was synthesised by a powder metallurgical method from ball milled TiC/Si powders of two different compositions, with TiC/Si ratios of 3:2 and 3:2.2 respectively. The cold pressed samples were analysed by dilatometry under flowing argon or sintered under vacuum for different times. The sintered samples were evaluated using x-ray diffraction (XRD). This study showed that titanium carbide was always present as a secondary phase and silicon carbide accompanied the Ti3SiC2 formation. Titanium silicide was observed in the samples of TiC/Si ratio 3:2 and is suggested to be an intermediate phase to the Ti3SiC2 formation in these samples. The melting of Si is essentially concurrent with the MAX phase formation in these samples and the evaporation of Si with its decomposition. The activation energy of Ti3SiC2 formation from 3TiC/2Si starting powders was determined to be 289 kJ/mol, using the Mehl-Avrami-Johnson model.The samples of TiC/Si ratio 3:2.2 extra silicon resulted in Ti3SiC2 of higher purity and the Si of the samples did not melt or evaporate. Furthermore, the thermochemical stability of the samples was increased by the extra silicon.

  • 22.
    Knutsson, Axel
    et al.
    Luleå tekniska universitet.
    Hedström, Peter
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Reverse martensitic transformation and resulting microstructure in a cold rolled metastable austenitic stainless steel2008In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 79, no 6, p. 433-439Article in journal (Refereed)
    Abstract [en]

    The reverse martensitic transformation in cold-rolled metastable austenitic stainless steel has been investigated via heat treatments performed for various temperatures and times. The microstructural evolution was evaluated by differential scanning calorimetry, X-ray diffraction and microscopy. Upon heat treatment, both diffusionless and diffusion-controlled mechanisms determine the final microstructure. The diffusion reversion from α′-martensite to austenite was found to be activated at about 450°C and the shear reversion is activated at higher temperatures with Af′ ∼600°C. The resulting microstructure for isothermal heat treatment at 650°C was austenitic, which inherits the α′-martensite lath morphology and is highly faulted. For isothermal heat treatments at temperatures above 700°C the faulted austenite was able to recrystallize and new austenite grains with a low defect density were formed. In addition, carbo-nitride precipitation was observed for samples heat treated at these temperatures, which leads to an increasing Ms-temperature and new α′-martensite formation upon cooling.

  • 23.
    Larsson, C
    et al.
    Linköping universitet.
    Odén, Magnus
    Hardness profile measurements in functionally graded WC-Co composites2004In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 382, no 1-2, p. 141-149Article in journal (Refereed)
    Abstract [en]

    Micro- and nanoindentation were used to determine hardness as a function of depth in two functionally graded WC-Co composites. The gradients were continuous (extended over ~70 and ~40 μm, respectively) and consisted of varying WC and Co phase volume fractions. Five comparable homogeneous samples with different Co contents and different average WC grain sizes were also used for direct comparison. A relationship between hardness and Co content was established for both the graded and the homogeneous samples wherein the hardness decreased with increasing Co content. The magnitude of the hardness was the same (for a given Co content) for the functionally graded and the homogeneous materials. The hardness measurements were also correlated with X-ray diffraction studies of thermal residual stresses and the absence of any major influence explained. It is generally concluded that the hardness values are dominated by the local Co content. Additionally, the examination of surface cracks around indents suggests that compositional gradients in WC-Co composites offer increased toughness

  • 24.
    Larsson, C.
    et al.
    Linköping universitet.
    Odén, Magnus
    X-ray diffraction determination of residual stresses in functionally graded WC-Co composites2004In: International journal of refractory metals & hard materials, ISSN 0958-0611, E-ISSN 2213-3917, Vol. 22, no 4-5, p. 177-184Article in journal (Refereed)
    Abstract [en]

    X-ray diffraction was used to determine the thermal residual stresses that develop in a functionally graded WC–Co composite. Stresses were measured in both WC and Co phases at various depths. Pole figures were obtained in order to determine optimal sample orientations that provided adequate intensity for measurements in the Co phase. For WC, the in-plane compressive residual stresses varied approximately between −300 and −500 MPa with depth below the surface. For the low volume fraction Co phase, the tensile residual stresses were approximately 600 MPa. The microstresses in the graded zone were attributed to the thermal mismatch between the WC and the Co phase during cooling from the liquid phase sintering temperature (1450 °C). The microstresses determined were in reasonable agreement with a prediction using Eshelby theory. The compressive macrostresses were attributed to the compositional gradient, a result further substantiated by the fact that no significant macrostresses were measured in a comparable homogeneous sample, i.e., without the compositional gradient. Thus, varying compositional gradients in WC–Co composites during fabrication can be expected to directly influence the macrostress component of the overall residual stress state.

  • 25.
    Mangalaraja, Ramalinga Viswanathan
    et al.
    Universidad de Concepción.
    Ananthakumar, Solaiappan
    CSIR, Materials and Minerals Division.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Lopez, Marta
    Universidad de Concepción.
    Camurri, Carlos Porro
    Universidad de Concepción.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Sintering, microstructural and mechanical characterization of combustion synthesized Y2O3 and Yb3+-Y2O32009In: Ceramic Society of Japan. Journal, ISSN 1882-0743, Vol. 117, no 1371, p. 1258-1262Article in journal (Refereed)
    Abstract [en]

    The present work highlights the microstructural features and mechanical properties of Y2O3 prepared with and without Yb3+ doping that processed through combustion synthesis involving various organic fuels such as urea, citric acid and glycine. Properties such as powder-now, particle packing, green density, % of shrinkage, sintered density, grain size, Vicker's microhardness (H-v) and fracture toughness (K-IC) were analyzed and compared with respect to the fuel sources. The as combusted precursors were calcined at 1100 degrees C for 4 h under oxygen atmosphere to obtain fully crystalline Y2O3 powders. Cylindrical pellets were fabricated as test specimens and sintered at 1600 degrees C for 3 h. The SEM images of the sintered yttria samples show an average grain size of < 3 mu m irrespective of the fuels. However, the mechanical properties show significant dependence on the fuels used. A maximum hardness of 6.8 +/- 0.1 and 7.0 +/- 0.1 GPa was obtained for Y2O3 and Yb3+ doped Y2O3 derived from glycine fuel. Whereas the maximum fracture toughness of 2.6 +/- 0.3 MPa m(1/2) was obtained for the samples derived from urea. The Yb3+ doping found to increase the bulk hardness of yttria from 0.2 to 0.6 GPa. The study contributes to appropriately select the fuels for obtaining high dense, mechanically stable yttria ceramics through combustion process.

  • 26.
    Mangalaraja, Ramalinga Viswanathan
    et al.
    Universidad de Concepción.
    Ananthakumar, Solaiappan
    NIIST, Materials & Minerals Division, Kerala.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Uma, Kasimayan
    Nagoya Institute of Technology.
    Lopez, Marta
    Universidad de Concepción.
    Camurri, Carlos Porro
    Universidad de Concepción.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Synthesis of nanocrystalline yttria through in-situ sulphated-combustion technique2009In: Ceramic Society of Japan. Journal, ISSN 1882-0743, Vol. 117, no 1370, p. 1065-1068Article in journal (Refereed)
    Abstract [en]

    An in-situ sulphated-combustion reaction was conducted on the precursor mixture consisting of yttrium nitrate, organic fuels (urea, citric acid and glycine) and 10 mol% ammonium sulphate [(NH4)(2)SO4] at 500 degrees C. Effect of sulphate addition on yttria particles morphology has been analyzed with respect to the types of fuels. In un-sulphated combustion, the calcined yttria powders showed rectangular particle morphology and low specific surface area. Whereas in sulphated-combustion spherical shaped yttria particles were achieved for glycine fuel. In the case of citric acid fuel, yttria powders with high specific surface area [26 m(2)/g] were obtained. For all the fuels, the sulphated-combustion reaction produced nanocrystalline yttria powders and they also had primary crystallite size below 4 nm in the as prepared conditions. Upon calcination at 1100 degrees C, these powders attained mean particle size of 50 nm which was confirmed by TEM.

  • 27.
    Mangalaraja, R.V.
    et al.
    University of Concepción.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedström, Peter
    Camurri, C.P.
    University of Concepción.
    Ananthakumar, S.
    Université Montpellier.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Microwave assisted combustion synthesis of nanocrystalline yttria and its powder characteristics2009In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 191, no 3, p. 309-314Article in journal (Refereed)
    Abstract [en]

    Microwave assisted combustion synthesis is used for fast and controlled processing of advanced ceramics. Single phase and sinter active nanocrystalline cubic yttria powders were successfully synthesized by microwave assisted combustion using the organic fuels urea, citric acid and glycine as reducing agents. The precursor powders were investigated by thermogravimetry (TG) and differential scanning colorimetry (DSC) analyses. The as-prepared precursors and the resulting oxide powders calcined at 1100 °C in oxygen atmosphere were characterized for their structure, particle size and morphology. The thermal analyses (TG/DSC), X-ray diffraction (XRD) and Fourier transform infra red (FT-IR) results demonstrate the effectiveness of the microwave assisted combustion synthesis. The scanning electron microscopy (SEM) observations show the different morphologies of as-prepared powders and transmission electron microscopy (TEM) shows the particle sizes in the range of 30-100 nm for calcined powders for different fuels. The results confirm that the homogeneous, nano scale yttria powders derived by microwave assisted combustion have high crystalline quality and the morphology of the as-prepared precursor powders depends on the nature of organic fuel used.

  • 28.
    Mangalaraja, R.V.
    et al.
    University of Concepción.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedström, Peter
    Kero, Ida
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Ramam, K.V.S.
    University of Concepción.
    Camurri, C.P.
    University of Concepción.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Combustion synthesis of Y2O3 and Yb-Y2O3: Part 1: Nanopowders and their characterization2008In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 208, no 1-3, p. 415-422Article in journal (Refereed)
    Abstract [en]

    Nanosized yttrium oxide and ytterbium doped yttrium oxide powders were prepared by ceramic combustion techniques such as flash combustion, citrate gel decomposition and glycine combustion using urea, citric acid and glycine respectively as fuels. As synthesized precursors and calcined powders were characterized for their structural, particle size and morphology, and the optimization of calcination process by differential scanning calorimetry and thermal gravimetry. The thermal analyses together with XRD results demonstrate the effectiveness of the combustion process for the synthesis of pure phase nanocrystalline powders. Nanocrystalline pure yttria powders were obtained by the calcination of as-prepared precursors at 1100 °C for 4 h.

  • 29.
    Mouzon, Johanne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Dujardin, C.
    Claude Bernard/Lyon1 University.
    Tillement, O.
    Claude Bernard/Lyon1 University.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Synthesis and optical properties of Yb0.6Y1.4O3 transparent ceramics2008In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 464, no 1-2, p. 407-411Article in journal (Refereed)
    Abstract [en]

    Transparent yttrium oxide ceramics doped with 30 at.% ytterbium were successfully produced by a combination of pre-sintering and hot isostatic pressing. The influence on the final transparency of different densification states and porosity configurations obtained by varying pre-sintering conditions were investigated by optical and electron microscopy. Our results show that densification prior to the final stage of sintering is necessary to limit final porosity. Samples showing open porosity were found to lead to pore entrapment because of the diffusion of argon inside the glass capsule during hot isostatic pressing. Transmittance measurements showed that the valence charge of the ytterbium ions was 3+ at the end of the process, indicating no effect of reduction when pre-sintering in vacuum was employed.

  • 30.
    Mouzon, Johanne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Glowacki, Emily
    Luleå tekniska universitet.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Comparison between slip-casting and uniaxial pressing for the fabrication of translucent yttria ceramics2008In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 43, no 8, p. 2849-2856Article in journal (Refereed)
    Abstract [en]

    Slip casting and uniaxial pressing were compared as first consolidation stages prior to cold isostatic pressing (CIP) to produce translucent yttria ceramics. In the first step, yttria slurries suitable for slip casting were prepared. The viscosity was optimized with respect to the starting agglomeration state, amount of dispersant, milling time, and number of milling balls. Secondly, pellets were prepared either by slip casting or uniaxial pressing and then cold-isostatically pressed. Finally, the pellets were made translucent by a combination of pre-sintering and hot isostatic pressing (HIP). Although slip-cast and pressed samples exhibited similar green-body densities after CIP and pre-sintering, the samples prepared by slip casting were more homogeneous in terms of translucency and microstructure throughout their bodies. This was attributed to the ability of slip casting to minimize density gradients during packing, and to the beneficial effect of ball-milling to remove larger agglomerates before casting. Therefore, slip casting as a first consolidation stage prior to CIP appears to be more suitable than uniaxial pressing in order to prepare homogeneous optical ceramics.

  • 31.
    Mouzon, Johanne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Lindbäck, Ture
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Influence of agglomeration on the transparency of yttria ceramics2008In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 91, no 10, p. 3380-3387Article in journal (Refereed)
    Abstract [en]

    In this work, five yttria powders with slightly different states of agglomeration, inherited from various procedures of dewatering the same precursor, were densified by a combination of vacuum sintering followed by hot isostatic pressing (HIP). In order to relate the densification behavior of each powder to its state of agglomeration, all powders were characterized by tap density measurements, X-ray diffraction, nitrogen adsorption, and laser scattering, while the microstructures of the corresponding densified samples were studied by optical and scanning electron microscopy. The five yttria powders produced sintered samples that differed remarkably from each other in terms of transparency. These discrepancies were related to the degree of fineness in the powders at two different levels. At the level of primary particles, fine and weakly agglomerated powder was very sinterable, causing abnormal grain growth to occur only in the very late stage of sintering. However, the resulting entrapped pores and reduction due to vacuum sintering were responsible for poor optical properties. At the agglomerate level, a bimodal size distribution was identified for all powders. For powders showing severe agglomeration of the primary particles, increasing the relative content of the smaller size population of agglomerates was found to trigger abnormal grain-growth earlier during presintering. This was attributed to the density around large agglomerates exceeding a critical threshold in the green bodies. Finally, transparency was achieved in samples for which presintering was stopped before grain growth became abnormal. This confirmed that the key to successfully obtaining transparency was to keep porosity intergranular, which could be removed subsequently by HIP treatment.

  • 32.
    Mouzon, Johanne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Maitre, A.
    Laboratoire Science des Procédés Céramiques et Traitements de Surface, UMR CNRS 6638, UFR Sciences et Techniques, 123 Avenue Albert Thomas, F-87060 Limoges Cedex.
    Frisk, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Lehto, Niklas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Odén, Magnus
    Fabrication of transparent yttria by HIP and the glass-encapsulation method2009In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 29, no 2, p. 311-316Article in journal (Refereed)
    Abstract [en]

    This method consists of a combination of vacuum sintering at 1600 °C followed by hot isostatic pressing (HIP) at 1500 °C of a highly agglomerated commercial powder. The use of evacuated glass capsules to perform HIP treatment allowed samples that showed open porosity after vacuum sintering to be sintered to transparency. The sintering response of the investigated powder was studied by careful microstructural observations using scanning electron microscopy and optical microscopy both in reflection and transmission. The successful key of this method was to keep porosity intergranular during pre-sintering, so that it can be removed subsequently by HIP treatment. It was found that agglomerates of closely packed particles are helpful to reach that purpose, since they densify fully and leave only intergranular porosity. However, performing HIP treatment at 1625 °C was found to result in opaque samples. This was attributed to the diffusion of argon inside the capsule. Contamination at different steps of processing was also investigated by inductively coupled plasma mass spectrometry (ICP-MS).

  • 33. Mouzon, Johanne
    et al.
    Nordell, Patricia
    Luleå tekniska universitet.
    Adrien, Thomas
    Luleå tekniska universitet.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Comparison of two different precipitation routes leading to Yb doped Y2O3 nano-particles2007In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 27, no 4, p. 1991-1998Article in journal (Refereed)
    Abstract [en]

    Two different precipitation routes leading to (YbxY1-x)2O3 nano-particles (with x = 0; 0.027; and 0.31) were compared, namely, precipitation of hydroxynitrate platelets and amorphous carbonate spherical particles. For both methods, the particle morphology was observed by scanning electron microscopy. X-ray diffraction studies of the unit cell, energy dispersive X-ray analysis and inductive coupled plasma spectroscopy were used to check the ytterbium distribution. The precipitation of amorphous carbonate was found to produce particles with uniform morphology and homogeneous distribution of ytterbium, while hydroxide precipitation favours the formation of hard and dense ytterbium-rich agglomerates. These differences are discussed in terms of precipitation, growth and agglomeration behaviour. The sinterability of both resulting powders is also discussed

  • 34. Mouzon, Johanne
    et al.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Alternative method to precipitation techniques for synthesizing yttrium oxide nanopowder2007In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 177, no 2, p. 77-82Article in journal (Refereed)
    Abstract [en]

    Yttrium oxide nano-powder has been successfully synthesized by a novel approach. In the first step, a foamy structure was produced by combustion synthesis using yttrium nitrate and glycine. This was followed by the addition of sulfate ions and calcination at 1100 °C for 4 h. The sulfated and unsulfated powders were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and the Brunauer-Emmett-Teller method (BET). The sinterability of the resulting powders was also studied by dilatometry. The studies indicated that this method not only allows for producing weakly-agglomerated nano-particles, but is also a very time-efficient process in comparison to precipitation techniques. Moreover, the possibility of performing all processing steps in a fully automated batch reactor was also considered.

  • 35. Mouzon, Johanne
    et al.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Tillement, Olivier
    Université C. Bernard Lyon I.
    Jorand, Yves
    GEMPPM, INSA Lyon.
    Effect of drying and dewatering on yttria precursors with transient morphology2006In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 89, no 10, p. 3094-3100Article in journal (Refereed)
    Abstract [en]

    The influence of drying and dewatering of a yttrium hydroxynitrate precursor with transient morphology was investigated. The ability of this precursor to form soft agglomerated nanoparticles after calcination is dependent on the dewatering method. Freeze drying leads to finer particles than other dewatering methods that involve removal of the solvent from its liquid state. As water is directly removed by sublimation during freeze drying, this method inhibits the formation of solid bridges between hydroxynitrate platelets. These bridges, which form with the other dewatering methods, destabilize the spheroidization process of the platelets during subsequent firing at high temperatures.

  • 36.
    Odén, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Rogström, L.
    Linköping University.
    Terner, Mark
    Hedström, Peter
    Almer, J.
    Argonne National Laboratory, Argonne, IL.
    llavsky, J.
    Argonne National Laboratory, Argonne, IL.
    In situ small-angle x-ray scattering study of nanostructure evolution during decomposition of arc evaporated TiAlN coatings2009In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 94, no 5, p. 53114-Article in journal (Refereed)
    Abstract [en]

    Small-angle x-ray scattering was used to study in situ decomposition of an arc evaporated TiAlN coating into cubic-TiN and cubic-AlN particles at elevated temperature. At the early stages of decomposition particles with ellipsoidal shape form, which grow and change shape to spherical particles at higher temperatures. The spherical particles grow at a rate of 0.18 Å/°C while coalescing

  • 37. Odén, Magnus
    et al.
    Schlauer, Christian
    Department of Engineering Materials, Department of Mechanical Engineering, Linköping University.
    Peng, Ru Lin
    Department of Engineering Materials, Department of Mechanical Engineering, Linköping University.
    Residual stresses in a nickel-based superalloy introduced by turning2002In: ECRS 6: proceedings of the 6th European Conference on Residual Stresses, Coimbra, Portugal, 10-12 July 2002 / [ed] A.M. Dias, Trans Tech Publications Inc., 2002, p. 173-178Conference paper (Refereed)
  • 38.
    Palmquist, J-P
    et al.
    Uppsala University, Department of Materials Chemistry, Ångström Laboratory.
    Czigany, Zs.
    Uppsala University, Department of Materials Chemistry, Ångström Laboratory.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Neidhardt, J.
    Department of Physics, IFM, Linköping University.
    Hultman, L.
    Department of Physics, IFM, Linköping University.
    Jansson, U.
    Uppsala University, Department of Materials Chemistry, Ångström Laboratory.
    Corrigendum to ‘Magnetron sputtered W-C films with C60 as carbon source': [Thin Solid Films 444 (2003) 29-37]2004In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 457, no 2, p. 406-Article in journal (Other academic)
  • 39.
    Peng, Ru Lin
    et al.
    Studsvik Neutron Research Laboratory, Uppsala University.
    Wang, Yan Dong
    Studsvik Neutron Research Laboratory, Uppsala University.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Almer, Jon
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Residual stress analysis in both As-deposited and annealed CrN coatings2005In: Residual Stresses VII: ICRS 7 ; proceedings of the 7th International Conference on Residual Stresses, ICRS-7, Xi'an, China, 14 - 17 June 2004, Uetikon-Zürich: Trans Tech Publications Inc., 2005, p. 643-648Conference paper (Refereed)
    Abstract [en]

    In this paper, we report on residual stress analysis in physical vapour deposited (PVD) CrN coatings. Two 9 μm thick coatings were grown on tool steel substrates with bias voltages of-50 V and -300 V, respectively. High-energy (E=80 keV) synchrotron radiation measurements have been performed to investigate residual stresses in both as-deposited and annealed CrN coatings. To understand the origins of non-linear distribution of lattice strain versus sin2Ψ for certain (hkl) planes in both coatings, a stress orientation distribution function (SODF) analysis has been carried out, which yields grain-orientation-dependent residual stresses. The results are compared to previous analyses using Reuss and Vook-Witt models on the as-deposited coatings.

  • 40.
    Plamquist, J.-P
    et al.
    Uppsala universitet.
    Czigany, Zs.
    Research Institute for Technical Physics and Materials Science, Budapest.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Neidhart, J.
    Linköping universitet.
    Hultman, L.
    Linköping universitet.
    Jansson, U.
    Uppsala universitet.
    Magnetron sputtered W-C films with C60 as a carbon source2003In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 444, no 1-2, p. 29-37Article in journal (Refereed)
    Abstract [en]

    Thin films in the W-C system were prepared by magnetron sputtering of W with coevaporated C60 as carbon source. Epitaxial deposition of different W-C phases is demonstrated. In addition, nanocrystalline tungsten carbide film growth is also observed. At low C60/W ratios, epitaxial growth of α-W with a solid solution of carbon was obtained on MgO(001) and Al2O3(001) at 400 °C. The carbon content in these films (10-20 at.%) was at least an order of magnitude higher than the maximum equilibrium solubility and gives rise to an extreme hardening effect. Nanoindentation measurements showed that the hardness of these films increased with the carbon content and values as high as 35 GPa were observed. At high C60/W ratios, films of the cubic β-WC1-x (x = 0-0.6) phase were deposited with a nanocrystalline microstructure. Films with a grain size

  • 41.
    Schlauer, Christian
    et al.
    Linköpings universitet.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Residual stress evolution and near-surface microstructure after turning of the nickel-based superalloy Inconel 7182005In: Zeitschrift für Metallkunde, ISSN 0044-3093, Vol. 96, no 4, p. 385-392Article in journal (Refereed)
    Abstract [en]

    Turning experiments have been carried out with the cutting speed and feed as variables that were systematically varied between 10 m min-1 and 1200 m min-1, and 0.1 mm and 0.5 mm, respectively, while all other cutting parameters were held constant. The arising residual stress distributions are presented and the influence of the varied machining parameters is investigated. Compressive residual stresses dominate the depth profiles but are often accompanied by a thin tensile residual stress layer at the surface. Microstructural investigations of near-surface cross-sections by means of transmission electron microscopy showed a zone where the grains had undergone plastic deformation, indicated by slip bands. On top of this layer, a surface layer exists where the grain size has radically decreased to only 50 nm to 130 nm. The grain size of the nanocrystalline layer is fairly constant for a certain cutting speed and feed, but depends on these cutting parameters. An increase in cutting speed and feed leads to larger grains in the nanocrystalline layer.

  • 42.
    Stjernberg, Jesper
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Antti, Marta-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Nordin, L-O
    LKAB Research and Development, Metlab.
    Odén, Magnus
    Linköping University, Division of Nanostructured Materials.
    Study of the degradation process of refractory bricks in rotary kilns2008In: Global roadmap for ceramics & ICC2 proceedings: 2nd International Congress on Ceramics ; June 29 - July 4, 2008, Verona, Italy / [ed] Alida Bellosi, Faenza: Institute of Science and Technology for Ceramics , 2008Conference paper (Refereed)
    Abstract [en]

    Iron ore pellets are commonly sintered in a kiln insulated with bricks, which wear and need to be replaced regularly. It is desirable to increase the lifetime of those bricks. Slag/brick compatibility tests have been performed in a laboratory furnace. Slag collected from a production kiln, three commercial bricks and additions of alkali were used. Alkali dissolves the mullite in the bricks, and form the phases nepheline and kalsilite. Characterization of the microstructure showed that the degradation of the bricks was enhanced by increased temperature and amount of alkali. The slag penetration depth is more affected by increased temperature than increased dwell time.

  • 43. Stjernberg, Jesper
    et al.
    Antti, Marta-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Odén, Magnus
    Linköpings universitet.
    Nordin, Lars-Olof
    LKAB.
    Degradation of refractory bricks used as thermal insulation in rotary kilns for iron ore pellet production: degradation of refractory bricks used as thermal insulation in rotary kilns2009In: International Journal of Applied Ceramic Technology, ISSN 1546-542X, Vol. 6, no 6, p. 717-726Article in journal (Refereed)
    Abstract [en]

    Degradation of bricks in an iron ore pellet producing kiln has been investigated. Lab-scale tests of brick/slag interaction performed under different temperatures, atmospheres, and alkali additions show that addition of alkali dissolves the mullite in the brick and leads to formation of the phase nepheline (Na2O·Al2O3·2SiO2). At a high temperature, the grain boundary where nepheline is formed disintegrates due to volume expansion. At increased temperature, the nepheline transforms to an amorphous phase. Thus, a wear mechanism is proposed in the kiln using these bricks that involves these chemical reactions in combination with erosion by the continuously flowing slag.

  • 44.
    Stjernberg, Jesper
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Ion, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Antti, Marta-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Nordin, Lars-Olof
    LKAB.
    Lindblom, Bo
    LKAB.
    Odén, Magnus
    Linköping University, Division of Nanostructured Materials.
    Extended studies of degradation mechanisms in the refractory lining of a rotary kiln for iron ore pellet production2012In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 32, no 8, p. 1519-1528Article in journal (Refereed)
    Abstract [en]

    Changes, over a period of 8 years, in the chemical composition and morphology of deposit and lining materials in a production rotary kiln for iron ore pellet manufacture are described. The following have been studied: two types of refractory brick used as lining material; deposited chunk materials from the lining; the interaction zones between deposits and linings. Morphological changes at the deposit/lining interface, and the active chemical reactions, are established. Larger hematite grains in the deposit material (5–50 μm) primarily remain at the original deposit/lining interface. The remainder penetrates fissures, voids and brick joints, forms a laminar structure with corundum from the bricks, and migrates in grains in the lining material. Potassium penetrates more deeply into the bricks than hematite, resulting in the formation of kalsilite, leucite and potassium β-alumina, which contribute to degradation of the lining.

  • 45.
    Stjernberg, Jesper
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Lindblom, B.
    LKAB.
    Wikström, J.
    LKAB.
    Antti, Marta-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Odén, Magnus
    Microstructural characterization of alkali metal mediated high temperature reactions in mullite based refractories2010In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 36, no 2, p. 733-740Article in journal (Refereed)
    Abstract [en]

    Two types of refractory bricks were used in reaction tests with slag from a production kiln for iron ore pellet production. Electron microscopy was used to characterize morphological changes at the slag/brick interface and active chemical reactions. Phases such as kalsilite, nepheline and potassium β-alumina form, in a layered structure, as a consequence of alkali metals migration in the brick. Larger hematite grains (50-100 μm) in the slag remain at the original slag/brick interface, while smaller grains dissolve and move through the partly dissolved brick bulk, and forms micrometer sized needle shaped crystals deeper in the lining material. Thermodynamic simulations predict the formation of a solid solution between hematite and corundum which is also observed in the reaction zone after extended time periods.

  • 46. Söderberg, Hans
    et al.
    Birch, Jens
    Thin Film Physics Division, IFM, Linköping University.
    Hultman, Lars
    Thin Film Physics Division, IFM, Linköping University.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    RHEED studies during growth of TiN/SiNx/TiN trilayers on MgO(001)2007In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 601, no 11, p. 2352-2356Article in journal (Refereed)
    Abstract [en]

    TiN/SiNx/TiN(0 0 1) trilayers have been deposited on MgO(0 0 1) substrates using ultra-high vacuum based reactive magnetron sputtering and studied by in situ reflection high energy electron diffraction (RHEED). Depositions were carried out at 500 °C and 800 °C, with SiNx layer thicknesses between 3 and 300 Å. Here, we find that SiNx(0 0 1) layers grown at 800 °C exhibit 1 × 4 surface reconstructions along orthogonal (1 1 0) directions up to a critical thickness of ≈9 Å, where an amorphous phase forms. Growth of TiN overlayers on the reconstructed SiNx(0 0 1) layers yield RHEED patterns indicating the growth of (0 0 1)-oriented epitaxial layers with a 1 × 1 reconstruction. For the case of amorphous SiNx layers the TiN overlayers grow polycrystalline.

  • 47. Söderberg, Hans
    et al.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Flink, Axel
    Thin Film Physics Division, Linköping University.
    Birch, Jens
    Thin Film Physics Division, Linköping University.
    Persson, Per O.Å
    Thin Film Physics Division, Linköping University.
    Beckers, Manfred
    Thin Film Physics Division, Linköping University.
    Hultman, Lars
    Thin Film Physics Division, Linköping University.
    Growth and characterization of TiN/SiN(001)superlattice films2007In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 22, no 11, p. 3255-3264Article in journal (Refereed)
    Abstract [en]

    We report the layer structure and composition in recently discovered TiN/SiN(001) superlattices deposited by dual-reactive magnetron sputtering on MgO(001) substrates. High-resolution transmission electron microscopy combined with Z-contrast scanning transmission electron microscopy, x-ray reflection, diffraction, and reciprocal-space mapping shows the formation of high-quality superlattices with coherently strained cubic TiN and SiN layers for SiN thickness below 7-10 Å. For increasing SiN layer thicknesses, a transformation from epitaxial to amorphous SiNx (x 1) occurs during growth. Elastic recoil detection analysis revealed an increase in nitrogen and argon content in SiNx layers during the phase transformation. The oxygen, carbon, and hydrogen contents in the multilayers were around the detection limit (∼0.1 at.%) with no indication of segregation to the layer interfaces. Nanoindentation experiments confirmed superlattice hardening in the films. The highest hardness of 40.4 ± 0.8 GPa was obtained for 20-Å TiN with 5-Å-thick SiN(001) interlayers, compared to monolithic TiN at 20.2 ± 0.9 GPa.

  • 48. Söderberg, Hans
    et al.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Larsson, Tommy
    Hultman, Lars
    Thin Film Physics Division, IFM, Linköping University.
    Molina-Aldareguia, Jon M.
    CEIT and TECNUN, Paseo de Manuel Lardizabal 15, 20018 San Sebastián.
    Epitaxial stabilization of cubic-SiNx in TiN/SiNx multilayers2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 88, p. 191902/1-191902/3Article in journal (Refereed)
    Abstract [en]

    The formation of cubic-phase SiNx is demonstrated in TiN/SiNx multilayers deposited by reactive dual magnetron sputtering. Transmission electron microscopy examination shows a transition from epitaxially stabilized growth of crystalline SiNx to amorphous growth as the layer thickness increases from 0.3 to 0.8 nm. The observations are supported by ab initio calculations on different polytypes, which show that the NaCl structure has the best lattice match to TiN. Calculations also reveal a large difference in elastic shear modulus between NaCl-SiNx and TiN. The results for phase structure and shear modulus offer an explanation for the superhardening effect determined by nanoindentation experiments.

  • 49. Söderberg, Hans
    et al.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Molina-Aldareguia, J.M.
    Department of Physics and Measurement Technology, Biology and Chemistry (IFM), Linköping University.
    Hultman, L.
    Thin Film Physics Division, Department of Physics and Measurement Technology, Biology and Chemistry (IFM), Linköping University.
    Nanostructure formation during deposition of TiN/SiNx nanomultilayer films by reactive dual magnetron sputtering2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 97, no 11, p. 114327-1Article in journal (Refereed)
    Abstract [en]

    Multilayer thin films consisting of titanium nitride (TiN) and silicon nitride (SiNx) layers with compositional modulation periodicities between 3.7 and 101.7 nm have been grown on silicon wafers using reactive magnetron sputtering. The TiN and SiNx layer thicknesses were varied between 2-100 nm and 0.1-2.8 nm, respectively. Electron microscopy and x-ray diffraction studies showed that the layering is flat with distinct interfaces. The deposited TiN layers were crystalline and exhibited a preferred 002 orientation for layer thicknesses of 4.5 nm and below. For larger TiN layer thicknesses, a mixed 111/002 preferred orientation was present as the competitive growth favored 111 texture in monolithic TiN films. SiNx layers exhibited an amorphous structure for layer thicknesses ≥0.8 nm; however, cubic crystalline silicon nitride phase was observed for layer thicknesses ≤0.3 nm. The formation of this metastable SiNx phase is explained by epitaxial stabilization to TiN. The microstructure of the multilayers displayed a columnar growth within the TiN layers with intermittent TiN renucleation after each SiNx layer. A nano-brick-wall structure was thus demonstrated over a range of periodicities. As-deposited films exhibited relatively constant residual stress levels of 1.3±0.7 GPa (compressive), independent of the layering. Nanoindentation was used to determine the hardness of the films, and the measurements showed an increase in hardness for the multilayered films compared to those for the monolithic SiNx and TiN films. The hardness results varied between 18 GPa for the monolithic TiN film up to 32 GPa for the hardest multilayer, which corresponds to the presence of cubic SiNx. For larger wavelengths, ≥20 nm, the observed hardness correlated to the layer thickness similar to a Hall-Petch dependence, but with a generalized power of 0.4. Sources of the hardness increase for shorter wavelengths are discussed, e.g., epitaxial stabilization of metastable cubic SiNx, coherency stress, and impeded dislocation activity.

  • 50. Terner, Mark
    et al.
    Hedström, Peter
    Almer, Jon
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Ilavsky, J.
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Odén, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Residual stress evolution during decomposition of Ti(1-x)Al(x)N coatings using high-energy X-rays2006In: Residual stresses VII: ECRS 7 ; proceedings of the 7th European Conference on Residual Stresses, Trans Tech Publications Inc., 2006, p. 619-624Conference paper (Refereed)
    Abstract [en]

    Residual stresses and microstructural changes during phase separation in Ti33Al67N coatings were examined using microfocused high energy x-rays from a synchrotron source. The transmission geometry allowed simultaneous acquisition of x-ray diffraction data over 360° and revealed that the decomposition at elevated temperatures occurred anisotropically, initiating preferentially along the film plane. The as-deposited compressive residual stress in the film plane first relaxed with annealing, before dramatically increasing concurrently with the initial stage of phase separation where metastable, nm-scale c-AlN platelets precipitated along the film direction. These findings were further supported from SAXS analyses.

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