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Zhang, H., Hedman, D., Feng, P., Han, G. & Akhtar, F. (2019). A high entropy B4(HfMo2TaTi)C and SiC ceramic composite. In: : . Paper presented at XVI ECerS CONFERENCE.
Open this publication in new window or tab >>A high entropy B4(HfMo2TaTi)C and SiC ceramic composite
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2019 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Refractory carbides HfC, Mo2C, TiC, TaC, B4C, and SiC were mixed with a molar ratio of 2:1:2:2:1:2 to fabricate multicomponent ceramic composite by pulsed current processing (PCP). From the starting materials that consist of face-centered cubic (FCC), hexagonal and rhombohedral crystal structures, the investigated carbide system is reported to form a single phase B4(HfMo2TaTi)C high-entropy ceramic (HEC) with SiC. The HEC phase contains uniform distribution of constitutional elements Hf, Mo, Ta, Ti, B and C, according to Energy dispersive X-ray spectroscopy (EDS) and wavelength dispersive X-ray spectroscopy (WDS) results.

The fabricated HEC phase displays a hexagonal crystal structure, with a high average lattice distortion of 8.26% (Figure 1). The HCP structure was observed by X-ray diffraction and selected area diffraction in transmission electron microscopy (TEM). Density-functional theory (DFT) optimization suggested that the hexagonal crystal structure has alternating layers of metal atoms and carbon/boron atoms, i.e. metal atoms of Hf, Mo, Ta and Ti were distributed on the (0001) plane in the hexagonal lattice, while the carbon/boron atoms formed hexagonal 2D grids on the (0002) plane in the hexagonal unit cell. Despite of the vast differences in the crystal structures and lattice parameters among the utilized carbides, the formation of the unique hexagonal lattice structure of B4HfMo2TaTi)C can be a result of independent diffusion of the metal and nonmetal atoms. The sintered HEC ceramic composite exhibits excellent oxidation resistance at mediate temperature, 900 ºC for 50h, and elevated temperature, 2000 ºC for 20 s. Nanoindentation test shows that the HEC phase has a high hardness of 35 GPa. The remarkable improvement compared to the theoretical hardness value estimated based on the rule of mixtures (23 GPa) was contributed by the severe lattice distortion in the hexagonal structure.

National Category
Materials Engineering
Identifiers
urn:nbn:se:ltu:diva-74894 (URN)
Conference
XVI ECerS CONFERENCE
Available from: 2019-06-24 Created: 2019-06-24 Last updated: 2019-06-24
Zhang, H., Hedman, D., Feng, P., Han, G. & Akhtar, F. (2019). A high-entropy B4(HfMo2TaTi)C and SiC ceramic composite. Dalton Transactions, 48(16), 5161-5167
Open this publication in new window or tab >>A high-entropy B4(HfMo2TaTi)C and SiC ceramic composite
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2019 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 16, p. 5161-5167Article in journal (Refereed) Published
Abstract [en]

A multicomponent composite of refractory carbides, B4C, HfC, Mo2C, TaC, TiC and SiC, of rhombohedral, face-centered cubic (FCC) and hexagonal crystal structures is reported to form a single phase B4(HfMo2TaTi)C ceramic with SiC. The independent diffusion of the metal and nonmetal atoms led to a unique hexagonal lattice structure of the B4(HfMo2TaTi)C ceramic with alternating layers of metal atoms and C/B atoms. In addition, the classical differences in the crystal structures and lattice parameters among the utilized carbides were overcome. Electron microscopy, X-ray diffraction and calculations using density functional theory (DFT) confirmed the formation of a single phase B4(HfMo2TaTi)C ceramic with a hexagonal close-packed (HCP) crystal structure. The DFT based crystal structure prediction suggests that the metal atoms of Hf, Mo, Ta and Ti are distributed on the (0001) plane in the HCP lattice, while the carbon/boron atoms form hexagonal 2D grids on the (0002) plane in the HCP unit cell. The nanoindentation of the high-entropy phase showed hardness values of 35 GPa compared to the theoretical hardness value estimated based on the rule of mixtures (23 GPa). The higher hardness was contributed by the solid solution strengthening effect in the multicomponent hexagonal structure. The addition of SiC as the secondary phase in the sintered material tailored the microstructure of the composite and offered oxidation resistance to the high-entropy ceramic composite at high temperatures.

Place, publisher, year, edition, pages
Royal Society of Medicine Press, 2019
National Category
Materials Engineering Ceramics Composite Science and Engineering Other Physics Topics
Research subject
Engineering Materials; Applied Physics
Identifiers
urn:nbn:se:ltu:diva-72953 (URN)10.1039/C8DT04555K (DOI)000465328200037 ()30778490 (PubMedID)2-s2.0-85064521555 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-08-20 (johcin)

Available from: 2019-02-20 Created: 2019-02-20 Last updated: 2019-08-20Bibliographically approved
Zhang, H., Hedman, D., Feng, P., Han, G. & Akhtar, F. (2019). Correction: A high-entropy B4(HfMo2TaTi)C and SiC ceramic composite. Dalton Transactions, 48(19), 6647-6647
Open this publication in new window or tab >>Correction: A high-entropy B4(HfMo2TaTi)C and SiC ceramic composite
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2019 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 19, p. 6647-6647Article in journal (Refereed) Published
Abstract [en]

The authors regret that there is an error in writing the crystal structure in the article. The authors would like to address as follows:

The presented XRD and TEM results revealed a hexagonal crystal structure. The following analyses including the identification of the lattice parameters and the DFT calculation were based on a hexagonal lattice. Therefore, the HCP (hexagonal close-packed) structure mentioned in the article should be regarded as a hexagonal structure. The HCP term used in the introduction, where the article from Joshua Gild et al. was cited, should also be regarded as hexagonal AlB2 structure.

The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

Place, publisher, year, edition, pages
Royal Society of Medicine Press, 2019
National Category
Materials Engineering Ceramics Composite Science and Engineering Other Physics Topics
Research subject
Engineering Materials; Applied Physics
Identifiers
urn:nbn:se:ltu:diva-74978 (URN)10.1039/C9DT90099C (DOI)000472451000039 ()2-s2.0-85065896417 (Scopus ID)
Note

Coorection to: A high-entropy B 4 (HfMo 2 TaTi)C and SiC ceramic composite

(2019) Dalton Transactions, 48 (16), pp. 5161-5167.DOI:10.1039/c8dt04555k

Available from: 2019-06-25 Created: 2019-06-25 Last updated: 2019-08-15Bibliographically approved
Liu, Y., Cai, X., Sun, Z., Zhang, H., Akhtar, F., Czujko, T. & Feng, P. (2019). Fabrication and Characterization of Highly Porous FeAl‐Based Intermetallics by Thermal Explosion Reaction. Paper presented at 2nd International Conference and Exhibition on Light Materials − Science and Technology(LightMAT2017), September 8-10, 2017, Bremen, Germany. Advanced Engineering Materials, 21(4), Article ID 1801110.
Open this publication in new window or tab >>Fabrication and Characterization of Highly Porous FeAl‐Based Intermetallics by Thermal Explosion Reaction
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2019 (English)In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 21, no 4, article id 1801110Article in journal (Refereed) Published
Abstract [en]

Porous FeAl-based intermetallics with different nominal compositions ranging from Fe–40 at% Al to Fe–60 at% Al are prepared by a novel process of thermal explosion (TE) mode. The results show that the Al content significantly affects the combustion behavior of the specimens, the ignition temperature of the Fe–Al intermetallics varies from 641 to 633 °C and the combustion temperature from 978 to 1179 °C. The porous materials exhibit uniform pore structures with porosities and average pore sizes of 52–61% and 20–25 µm, respectively. The TE reaction is the dominant pore formation mechanism regardless of the alloy composition. However, differences in the porosity and average pore size are observed depending on the Al content. The compressive strength of porous Fe–Al intermetallics is in the range of 23–34 MPa, duly applied as filters. Additionally, a surface alumina layer is formed at the early stage and both of the oxidation process and the sulfidation process follows the familiar parabolic rate law in the given atmosphere, exhibiting excellent resistance to oxidation and sulfidation. These results suggest that the porous Fe–Al intermetallics are promising materials for applications in harsh environments with a high-temperature sulfide-bearing atmosphere, such as in the coal chemical industry.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
FeAl intermetallics, microstructure, porous material, properties, thermal explosion
National Category
Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-72765 (URN)10.1002/adem.201801110 (DOI)2-s2.0-85060210181 (Scopus ID)
Conference
2nd International Conference and Exhibition on Light Materials − Science and Technology(LightMAT2017), September 8-10, 2017, Bremen, Germany
Note

Konferensartikel i tidskrift

Available from: 2019-02-01 Created: 2019-02-01 Last updated: 2019-06-26Bibliographically approved
Zhang, H. & Akhtar, F. (2019). Processing and Characterization of Refractory Quaternary and Quinary High-Entropy Carbide Composite. Entropy, 21(5), Article ID 474.
Open this publication in new window or tab >>Processing and Characterization of Refractory Quaternary and Quinary High-Entropy Carbide Composite
2019 (English)In: Entropy, ISSN 1099-4300, E-ISSN 1099-4300, Vol. 21, no 5, article id 474Article in journal (Refereed) Published
Abstract [en]

Quaternary high-entropy ceramic (HEC) composite was synthesized from HfC, Mo2C, TaC, and TiC in pulsed current processing. A high-entropy solid solution that contained all principal elements along with a minor amount of a Ta-rich phase was observed in the microstructure. The high entropy phase and Ta-rich phase displayed a face-centered cubic (FCC) crystal structure with similar lattice parameters, suggesting that TaC acted as a solvent carbide during phase evolution. The addition of B4C to the quaternary carbide system induced the formation of two high-entropy solid solutions with different elemental compositions. With the increase in the number of principal elements, on the addition of B4C, the crystal structure of the HEC phase transformed from FCC to a hexagonal structure. The study on the effect of starting particle sizes on the phase composition and properties of the HEC composites showed that reducing the size of solute carbide components HfC, Mo2C, and TiC could effectively promote the interdiffusion process, resulting in a higher fraction of a hexagonal structured HEC phase in the material. On the other hand, tuning the particle size of solvent carbide, TaC, showed a negligible effect on the composition of the final product. However, reducing the TaC size from −325 mesh down to <1 µm resulted in an improvement of the nanohardness of the HEC composite from 21 GPa to 23 GPa. These findings suggested the possibility of forming a high-entropy ceramic phase despite the vast difference in the precursor crystal structures, provided a clearer understanding of the phase transformation process which could be applied for the designing of HEC materials.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
high-entropy ceramic, solid-state diffusion, microstructure, phase evolution, hardness
National Category
Other Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-73885 (URN)10.3390/e21050474 (DOI)000472675900038 ()2-s2.0-85066624692 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-06-05 (oliekm)

Available from: 2019-05-09 Created: 2019-05-09 Last updated: 2019-08-15Bibliographically approved
Jiang, Z., Feng, P., Wang, X., Zhang, H. & Liu, Y. (2018). Combustion synthesis and mechanical properties of MoSi2­-ZrB2­-SiC ceramics. Journal of the Ceramic Society of Japan, 126(7), 504-509
Open this publication in new window or tab >>Combustion synthesis and mechanical properties of MoSi2­-ZrB2­-SiC ceramics
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2018 (English)In: Journal of the Ceramic Society of Japan, ISSN 1882-0743, Vol. 126, no 7, p. 504-509Article in journal (Refereed) Published
Abstract [en]

MoSi2ZrB2SiC ceramics were synthesized using Mo, Zr, Si and B4C powders by self-propagating high-temperature synthesis and densifying by spark plasma sintering. The effects of MoSi2 content on the combustion synthesis process, microstructure, and mechanical properties of the ceramics were investigated. The results showed that combustion synthesis is an unstable mode, spiral combustion. The Gibbs calculations and combustion temperature curves indicate there are two reactions occurring at the same time. The volume fraction of the four different phases and their relative densities were also measured and calculated. Compared to pure MoSi2, the 1.0MoSi20.2ZrB20.1SiC (M10) ceramic exhibits excellent mechanical properties with its maximum Vickers hardness and fracture toughness being 14.0 GPa and of 5.5 MPa m1/2, respectively. The hardness is in agreement with the rule of mixture. The morphology of indentation cracks reveals that the fracture toughness improves as a result of toughening mechanisms such as crack bridge, crack deflection, and microcracks.

Place, publisher, year, edition, pages
Ceramic Society of Japan, 2018
Keywords
Combustion synthesis, In situ, Spark plasma sintering, Mechanical properties, MoSi2
National Category
Ceramics Other Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-70244 (URN)10.2109/jcersj2.17261 (DOI)000437358200002 ()2-s2.0-85049330174 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-08-09 (andbra)

Available from: 2018-08-07 Created: 2018-08-07 Last updated: 2018-08-09Bibliographically approved
Zhang, H. (2018). Synthesis of metallic/high entropy ceramic composite and a study of the phase transformation mechanism. (Licentiate dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Synthesis of metallic/high entropy ceramic composite and a study of the phase transformation mechanism
2018 (English)Licentiate thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2018
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Materials Engineering Other Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-71600 (URN)978-91-7790-270-6 (ISBN)978-91-7790-271-3 (ISBN)
Presentation
2018-12-20, E231, Luleå University of Technology, Luleå, 09:00 (English)
Opponent
Supervisors
Available from: 2018-11-19 Created: 2018-11-15 Last updated: 2018-12-08Bibliographically approved
Zhang, H., Feng, P. & Akhtar, F. (2017). Aluminium matrix tungsten aluminide and tungsten reinforced composites by solid-state diffusion mechanism. Scientific Reports, 7(1), Article ID 12391.
Open this publication in new window or tab >>Aluminium matrix tungsten aluminide and tungsten reinforced composites by solid-state diffusion mechanism
2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, no 1, article id 12391Article in journal (Refereed) Published
Abstract [en]

In-situ processing of tungsten aluminide and tungsten reinforced aluminium matrix composites from elemental tungsten (W) and aluminium (Al) was investigated by thermal analysis and pulsed current processing (PCP). The formation mechanism of tungsten aluminides in 80 at.% Al-20 at.% W system was controlled by atomic diffusion. The particle size of W and Al in the starting powder mixture regulated the phase formation and microstructure. PCP of micron sized elemental Al and W resulted in formation of particulate reinforcements, W, Al4W and Al12W, dispersed in Al matrix. W particles were surrounded by a ~3 μm thick dual-layer structure of Al12W and Al4W. The hardness of Al matrix, containing Al12W reinforcements, was increased by 50% compared to pure Al, from 0.3 GPa to 0.45 GPa and W reinforcements showed a hardness of 4.35 GPa. On PCP of 80 at.% Al-20 at.% W mixture with particle size of W and Al ~70 nm, resulted in formation of Al4W as major phase along with small fractions of Al5W and unreacted W phase. This suggested strongly that the particle size of the starting elemental Al and W could be the controlling parameter in processing and tailoring of phase evolution, microstructure of particulate reinforced Al matrix composite.

Place, publisher, year, edition, pages
Nature Publishing Group, 2017
National Category
Other Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-65925 (URN)10.1038/s41598-017-12302-w (DOI)000412000100006 ()28959027 (PubMedID)2-s2.0-85030115396 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-10-03 (andbra)

Available from: 2017-10-03 Created: 2017-10-03 Last updated: 2018-06-14Bibliographically approved
Forouzan, F., Zhang, H., Vuorinen, E. & Mücklich, F. (2017). Study of The Kinetics of Precipitation in an AHSS steel after Laser Welding and Quenching and Partitioning. In: : . Paper presented at International Materials Research Meeting In The Greater Region, Saarbrücken, 6-7 April 2017.
Open this publication in new window or tab >>Study of The Kinetics of Precipitation in an AHSS steel after Laser Welding and Quenching and Partitioning
2017 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Metallurgy and Metallic Materials Other Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-63375 (URN)
Conference
International Materials Research Meeting In The Greater Region, Saarbrücken, 6-7 April 2017
Available from: 2017-05-17 Created: 2017-05-17 Last updated: 2018-06-14Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0111-4558

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