Preparation of High-Entropy (Zr 0.25 Hf 0.25 Ta 0.25 Ti 0.25 )C-Ni-Co Composite by Spark Plasma Sintering
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UCTION
CURRENTLY, high-entropy alloys (HEAs) have been one of the most appealing research topics.[1–4] In principle, high-entropy materials contain four or more elements in near-equiatomic proportions, having a highly disordered homogeneous crystalline single phase.[5,6] Their uncommon compositions and chemical structures allow them to achieve excellent combinations of mechanical properties such as high strength,[7,8] remarkable hardness,[9] extraordinary thermal stability,[10] good wear resistance[11,12] and oxidation resistance,[13] and so on. The combination of these properties makes them potential for structural materials. JUNBO LIU, JI XIONG, ZHIXING GUO, TIAN’EN YANG, LU YANG, and WU ZHAO are with the School of Mechanical Engineering, Sichuan University, Chengdu, 610065, P. R. China. Contact e-mail: [email protected] HONGLIN ZHOU is with the School of Mechanical Engineering, Sichuan University and with the Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 19019. Manuscript submitted June 14, 2020. Accepted September 14, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS A
Recently, based on the HEAs, the novel design concepts have been extended to the field of ceramics. High-entropy ceramics including oxides,[14–17] [18,19] [20–22] nitrides, carbides, diborides,[23–25] sili[26,27] and single-phase metal oxycarbonitride cides ceramics[28] have also been successfully manufactured and characterized. In particular, high-entropy metal carbide ceramics have attracted increasing attention because of their distinguished properties, such as higher hardness, better environmental resistance and lower thermal conductivity than other single-phase compounds. Thus, many researchers focused on the preparation and properties of the high-entropy metal carbide ceramics. At the early age, a single-phase high-entropy (Cr0.2Nb0.2Ti0.2V0.2W0.2)C carbide bulk was fabricated by Yeh et al. via mechanical alloying and subsequent solid sintering,[29] but due to the segregation in the materials, the properties of the carbide were not given. Another work by Dusza et al.[30] introduced a new single-phase (Hf0.25Ta0.25Zr0.25Nb0.25)C material. There was no detectable segregation in the materials at the micro- and nano-level, and the homogeneity of the microstructure was greatly enhanced. Recently, Yan
et al. prepared a homogeneous five-component (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)C carbide bulk, and the material showed significant high hardness and elasticity as well as low thermal conductivity.[31] However, the enhancement of comprehensive performance was not ideal. When used in engineering applications as cutting tools and wear-resistant parts in hypervelocity-finishing and nuclear energy systems, high-entropy ceramics are destroyed easily because of brittle failure. Metal-ceramic composites exhibit a combination of the good properties of metals and ceramics, showing remarkable performance. Some studies on HEA-ceramic composites have been explored in experiments to improve the mechanical propertie
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