Change search
Refine search result
1 - 9 of 9
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Dewi, Handika Sandra
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Volpp, Jörg
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Kaplan, Alexander F.H.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Influence of secondary-pass laser treatment on retained ferrite and martensite in 44MnSiVS6 microalloyed steel2022In: Materials Today Communications, ISSN 2352-4928, Vol. 31, article id 103282Article in journal (Refereed)
    Abstract [en]

    Overlapping regions of laser surface treatment are necessary features when processing large surface areas or cylindrical specimens. However, complex microstructural changes that appear in the regions with multiple heat treatment can affect their mechanical properties. Therefore, this study focuses on examining thermal cycle characteristics and resulting microstructures, particularly martensite and retained ferrite structures, to better understand the correlation between experienced thermal cycles and resulting microstructures. Laser surface hardening experiments on 44MnSiVS6 microalloyed steels together with thermal diffusion simulations were conducted to relate microstructures after the secondary pass of the laser treatment to the local thermal cycles experienced during the process. The amount of retained ferrite was calculated and compared to the respective thermal cycle characteristics. Regions which experienced thermal cycles below Ac3 temperature showed microstructures similar to those after tempering. The sizes of retained ferrite structures were found to decrease as the total holding time increases regardless of how the holding time is distributed in multiple laser treatments. However, the size of retained ferrite structures were constant in the region where tempering effect occurred. This shows that the amount of retained ferrite can be tailored by modifying the experienced total holding time and a reduction of retained ferrite structure happens only if the secondary thermal cycle is above Ac3 temperature.

    Download full text (pdf)
    fulltext
  • 2.
    Fedina, Tatiana
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Sundqvist, Jesper
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Kaplan, Alexander F.H.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Spattering and oxidation phenomena during recycling of low alloy steel powder in Laser Powder Bed Fusion2021In: Materials Today Communications, ISSN 2352-4928, Vol. 27, article id 102241Article in journal (Refereed)
    Abstract [en]

    This study reports on the impact of repeated powder recycling on the degradation of low alloy steel powder in Laser Powder Bed Fusion. The average powder particle size increased slightly upon recycling due to powder agglomeration and the presence of spatters and other ejecta from the process zone. The oxygen content showed a continuous growth after each recycle, while the other chemical elements of the recycled powder remained largely unchanged. A map of ejecta classification is presented, featuring various ejecta types formed during laser processing. Ejecta of increased diameter and different shapes were observed in the recycled powder, using high-speed imaging and Scanning Electron Microscopy. The ejecta were collected after each powder recycle to enable the calculation of the ejecta mass generated during the process. The result showed a direct correlation between oxygen content in the powder and spatter/ejecta formation with the number of recycling events. It is likely that the increase in oxygen contributes to powder spattering.

  • 3.
    He, Shuang
    et al.
    School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China.
    Tan, Qiankun
    School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China.
    Chen, Xu
    School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China.
    Liu, Ye
    School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China.
    Gorbatov, Oleg I.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Peng, Ping
    School of Materials Science and Engineering, Hunan University, Changsha 410082, China.
    First-principles study of Re-W interactions and their effects on the mechanical properties of γ/γ' interface in Ni-based single-crystal alloys2023In: Materials Today Communications, ISSN 2352-4928, Vol. 36, article id 106662Article in journal (Refereed)
    Abstract [en]

    The distribution of solutes and their interactions play a crucial role in determining the mechanical properties of the γ/γ′ interface in Ni-based single-crystal alloys. In this study, atomic interactions between Re and W and their alloying effects on the inter-phase cohesion of the γ/γ′ interface are investigated by first-principles calculations. Our results show that W atom exhibits a preference for partitioning into the γ phase, while the stability of the γ/γ′ interface can be enhanced due to the partitioning of W to the γ′ phase. Moreover, our results reveal that partitioned W atoms in the γ′ phase contribute to the strengthening of the γ/γ′ interface. Conversely, the dissolution of W atoms in the γ phase weakens the inter-phase cohesion. However, this detrimental effect can be mitigated by introducing of Re into the γ/γ′ interface. Partitioning of Re and W into separate phases yields minimal alterations in interaction energies, resulting in a notable enhancement of inter-phase cohesion when compared to the partitioning of Re and W within γ phase of the γ/γ′ interface. Additionally, the partitioning of solute atoms at the γ/γ′ interface leads to local lattice distortion and interfacial energy reduction, which contribute to the enhancement of inter-phase cohesion of the γ/γ′ interface. As a result, a model is proposed for interpretation of crack propagation at the γ/γ′ interface at the threshold region with the presence of tensile stress in Ni-based single-crystal alloys.

  • 4.
    Hosseini, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Forouzan, Farnoosh
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vuorinen, Esa
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    In-situ microstructural evolution during quenching and partitioning of a high-carbon steel by high-temperature X-Ray diffraction2022In: Materials Today Communications, ISSN 2352-4928, Vol. 31, article id 103503Article in journal (Refereed)
    Abstract [en]

    Carbon partitioning from martensite to austenite is essential for austenite stabilization during quenching and partitioning (Q&P), while a few competitive phenomena, such as bainitic transformation and carbide precipitation, alter the microstructural evolution. So, there is a need of using in-situ in combination with ex-situ characterisation techniques to understand the C partitioning at high temperature in relation to simultaneous competitive phenomena that might occur during the partitioning stage.

    In this study, microstructural evolutions of a medium carbon steel ( 0.6C–1.6Si–1.25Mn–1.75Cr wt%) during Q&P treatment were investigated by using an in-situ High-Temperature X-Ray Diffraction (HTXRD) equipment at three partitioning temperatures. Results confirmed that carbon enrichment of austenite at 280 and 400 ℃ originates from partial carbon depletion from martensite and bainitic transformation, while partitioning at 500 ℃ results in the complete depletion of carbon from initial martensite and ferrite formation. Short diffusion distance (~0.13 µm) of carbon at 280 ℃ caused a poor carbon homogenization of austenite and formation of 8 vol% fresh martensite after final quenching. High Si content of the steel stabilized transitional carbides and, concurrently, suppressed Fe3C formation during Q&P. The outcome of this study could contribute to the design of suitable chemistry and process parameters for producing quenched and partitioned steels.

  • 5.
    Lupi, Giorgia
    et al.
    Department of Mechanical Engineering, Politecnico di Milano, Via G. La Masa 34, 20156 Milano (MI), Italy.
    de Menezes, João Teixeira Oliveira
    Department of Mechanical Engineering, Politecnico di Milano, Via G. La Masa 34, 20156 Milano (MI), Italy.
    Belelli, Filippo
    Department of Mechanical Engineering, Politecnico di Milano, Via G. La Masa 34, 20156 Milano (MI), Italy.
    Bruzzo, Francesco
    Fraunhofer, Institut für Werkstoff und Strahltechnik, Winterbergstraße 28, 01277 Dresden, Germany.
    López, Elena
    Fraunhofer, Institut für Werkstoff und Strahltechnik, Winterbergstraße 28, 01277 Dresden, Germany.
    Volpp, Joerg
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Castrodeza, Enrique Mariano
    Department of Mechanical Engineering, Politecnico di Milano, Via G. La Masa 34, 20156 Milano (MI), Italy.
    Casati, Riccardo
    Department of Mechanical Engineering, Politecnico di Milano, Via G. La Masa 34, 20156 Milano (MI), Italy.
    Fracture toughness of AlSi10Mg alloy produced by direct energy deposition with different crack plane orientations2023In: Materials Today Communications, ISSN 2352-4928, Vol. 37, article id 107460Article in journal (Refereed)
    Abstract [en]

    Three-point bending fracture toughness and tensile specimens were tested at room temperature along different crack plane orientations and loading directions. Before being machined and tested, the printed samples were subjected to heat treatment at 300 °C for 2 h to relieve the residual stresses. Microstructural and fractographic analyses were performed to investigate the fracture mechanisms and the crack propagation paths for each crack orientation. Significant differences in the fracture toughness were observed among the crack plane orientations. Specimens with cracks oriented in the X-Y direction featured the highest fracture toughness values (JIc = 11.96 kJ/m2), whereas the Z-Y crack orientation (perpendicular to the printing direction) performed the lowest fracture toughness values (JIc = 8.91 kJ/m2). The anisotropy in fracture toughness is mainly related to a preferential crack propagation path along the melt pool boundaries. At melt pool boundaries, pores are preferentially placed, coarsening of the microstructure occurs and there is higher Si content, leading to that area being less ductile and less resistant to crack propagation.

    Download full text (pdf)
    fulltext
  • 6.
    Shanmugam, Vigneshwaran
    et al.
    Department of Mechanical Engineering, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai 602 105, Tamilnadu, India.
    Sreenivasan, S.N.
    Department of Mechanical Engineering, Adishankara Institute of Engineering and Technology, Kalady Kerala – 683574, India.
    Mensah, Rhoda Afriyie
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Försth, Michael
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Hedenqvist, Mikael S
    Department of Fibre and Polymer Technology, Polymeric Materials Division, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm 100 44, Sweden.
    Neisiany, Rasoul Esmaeely
    Department of Materials and Polymer Engineering, Faculty of Engineering, Hakim Sabzevari University, Sabzevar, 9617976487, Iran.
    Tu, Yongming
    Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology NTNU, S.P. Andersens Veg 3, Trondheim, 7031, Norway; School of Civil Engineering, Southeast University, Nanjing 211189, China.
    Das, Oisik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    A Review on Combustion and Mechanical Behaviour of Pyrolysis Biochar2022In: Materials Today Communications, ISSN 2352-4928, Vol. 31, article id 103629Article, review/survey (Refereed)
    Abstract [en]

    Biochar has unique physical and chemical properties, making it a viable and sustainable future generation material for a variety of applications. The applications include power generation, composite production, construction (as a reinforcement), and soil amendment. The inherent good mechanical and combustion (or fire) resistance properties of biochar are attractive, however, there are limited reports, despite its effects on bulk material properties being well-documented. Comprehending these innate properties of biochar is critical for tailoring the mechanical and fire properties of biochar-based materials and structures. Therefore, an attempt has been made in this article to garner and analyse literatures reported on the mechanical and combustion properties of biochar without being integrated with a material or structural system (e.g. composite). Biochar produced at high pyrolysis temperatures (>500 ℃) showed high fire resistance property, because of the absence of the volatile matters and development of strong C-C covalent bonds. The mechanical and combustion properties of biocharcan be controlled by varying the biochar size, porus nature, and pyrolysis temperature. The information presented in this article is crucial and can be used as a guide to develop biochar-based materials and structures for mechanical and fire resistance applications.

  • 7.
    Xing, Qiuwei
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Feltrin, Ana Carolina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Akhtar, Farid
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Processing, microstructure and high temperature dry sliding wear of a Cr-Fe-Hf-Mn-Ti-Ta-V high-entropy alloy based composite2021In: Materials Today Communications, ISSN 2352-4928, Vol. 28, article id 102657Article in journal (Refereed)
    Abstract [en]

    High-entropy materials are promising for high-temperature applications. In order to achieve high-temperature wear resistance, a novel high-entropy alloy based composite, (CrMnFeHf)7.14(TiTaV)23.81, was designed and consolidated by spark plasma sintering at 1320 ℃ following thermodynamic simulations using the CALPHAD method. The microstructure of the sintered composite revealed a Ti30V36Ta19Cr5Mn5Fe4Hf1 body-centered cubic (bcc) high-entropy alloy matrix with C14 Laves phase and carbide particles. The Laves phase and carbide particles of higher hardness were formed in situ during the sintering in a bcc matrix. The dry sliding wear behavior of the composite against Si3N4 ceramic counter ball (10 N, 30 min) from room temperature to 600 ℃ was investigated. The high-entropy alloy composite showed a superior resistance to wear against Si3N4 ceramic due to the presence of reinforcing C14 laves phase and carbide particles in the high-entropy alloy matrix. Furthermore, the wear rate reduced with increasing temperature. The dominating wear mechanisms of the high-entropy alloy composite were adhesive wear and abrasive wear at room temperature and 200 ℃, oxidation wear and abrasive wear at 400 ℃ and oxidation wear and delamination wear at 600 ℃. The formation of multiple oxides, presence of Laves and carbide phase contributed to the low volume loss of high-entropy alloy composite during wear tests at high temperatures.

  • 8.
    Zhao, Jun
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029, China; State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China.
    Gao, Tong
    College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
    Li, Yingru
    School of Advanced Materials and Mechatronic Engineering, Hubei Minzu University, Enshi, 445000, China.
    He, Yongyong
    State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China.
    Shi, Yijun
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Two-dimensional (2D) graphene nanosheets as advanced lubricant additives: A critical review and prospect2021In: Materials Today Communications, ISSN 2352-4928, Vol. 29, article id 102755Article in journal (Refereed)
    Abstract [en]

    Graphene is a two-dimensional nanomaterial with a monolayer of atomic thickness. Due to its high specific surface area, weak interlayer interaction and good chemical stability, graphene has shown remarkable tribological properties as a lubricant additive. This review focuses on the research progress on graphene-based additives witnessed in recent years. Various synthesis methods of graphene nanomaterials have been displayed, and the review especially highlights the preparation processes of graphene using as a lubricant additive. The dispersion stability of graphene in lubricants is a key concern that has been presented. Besides physical and chemical modifications, a new dispersion method of structural regulation, which has obvious self-dispersed effect, is also discussed in detail. Furthermore, the lubrication mechanisms of graphene additives have been summarized, which will be highly beneficial to optimize the synthesis processes and to regulate the microstructures of graphene for achieving better lubrication. Finally, the challenges and outlook of the future studies on graphene additives are presented in the field of lubrication.

  • 9.
    Zulfiqar, Waqas
    et al.
    Computational Materials Modeling Laboratory, Department of Physics, Government College University, Faisalabad, 38040, Faisalabad, Pakistan; Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
    Alay-e-Abbas, Syed Muhammad
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Computational Materials Modeling Laboratory, Department of Physics, Government College University, Faisalabad, 38040, Faisalabad, Pakistan.
    Improved Thermodynamic Stability and Visible Light Absorption in Zr+X Codoped (X = S, Se and Te) BaTiO3 Photocatalysts: A First-Principles Study2022In: Materials Today Communications, ISSN 2352-4928, Vol. 32, article id 103867Article in journal (Refereed)
    Abstract [en]

    Band gap tuning of titanium based perovskite oxides through chalcogen doping is an attractive avenue for realizing visible light driven photocatalysis for hydrogen production. Unfortunately, accommodating a chalcogen atom at an O-site of BaTiO3 is thermodynamically challenging owing to large differences in the atomic radii and electronegativities of oxygen and chalcogen atoms. In the present study we employ first-principles density functional theory calculations to examine the influence of Zr codoping on the structural, thermodynamic, opto-electronic properties and photocatalytic performance of X-doped (X = S, Se and Te) BaTiO3 systems. The atomic structure and energetic properties are computed using SCAN meta-GGA functional of density functional theory, while the electronic and optical properties are computed using the TB-mBJ meta-GGA potential functional. Within the valid limits of the atomic chemical potentials, we find that chalcogen doping in BaTiO3 lattice would be experimentally difficult despite a clear reduction in the electronic band gap of this system useful for application in visible light driven photocatalysis. In order to improve the synthesis feasibility of X-doped BaTiO3 under oxygen-rich as well as oxygen-poor chemical environments, we propose Zr as a codopant at a Ti-site in X-doped BaTiO3 which improves the thermodynamic stability and also retains the reduction in the electronic band gap of BaTiO3 caused by the presence of chalcogen atom. Our results suggest that Zr+X (X = S, Se and Te) codoped BaTiO3 offers great opportunities as a practical photocatalysts for hydrogen production through overall splitting of the water molecule.

1 - 9 of 9
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf