1. Toughened bulk high-entropy diborides with high hardness and enhanced oxidation resistance via SiC whiskers.
- Author
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Yang, Yao, Bi, Jianqiang, Sun, Kangning, Hou, Hongli, Qiao, Linjing, Liang, Guandong, Wang, Shaoyin, Liang, Shuyong, Yuan, Jilie, and Chen, Yueguang
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HARDNESS , *SPECIFIC gravity , *FRACTURE toughness , *OXIDATION , *SILICON carbide - Abstract
The fracture toughness and oxidation resistance are crucial factors affecting the practical applications of high-entropy diboride ceramics (HEBs). In this study, silicon carbide whiskers (SiC w) were introduced as a reinforcement for HEBs for the first time. To achieve a uniform dispersion of SiC w within the HEB powders, a combination of simultaneous ultrasonic dispersion, mechanical agitation, and freeze-drying technology was employed. Consequently, a series of composites, (Hf 0.2 Zr 0.2 Ta 0.2 V 0.2 Nb 0.2)B 2 -nSiC w (n = 0–20 vol%), were densified by spark plasma sintering. The effect of SiC w on the microstructure and mechanical properties of the HEBs were studied, as well as the toughening mechanism involved. The results revealed that the introduction of SiC w led to grain-size refinement in (Hf 0.2 Zr 0.2 Ta 0.2 V 0.2 Nb 0.2)B 2 , along with significant improvements in relative density, hardness, fracture toughness, and oxidation resistance. The relative density, hardness and fracture-toughness of (Hf 0.2 Zr 0.2 Ta 0.2 V 0.2 Nb 0.2)B 2 -SiC w composites exhibited an initial increase followed by a decrease with increasing SiC w content. Specifically, the (Hf 0.2 Zr 0.2 Ta 0.2 V 0.2 Nb 0.2)B 2 –15 vol% SiC w composite simultaneously obtained the highest hardness of 25.6 GPa and fracture-toughness of 4.8 MPa·m1/2, representing a 26% improvement compared to (Hf 0.2 Zr 0.2 Ta 0.2 V 0.2 Nb 0.2)B 2 ceramics. • The effect of SiC w on microstructure, mechanical properties and oxidation resistance of HEBs were studied for the first time. • The K Ic of (Hf 0.2 Zr 0.2 Ta 0.2 V 0.2 Nb 0.2)B 2 ceramic was increased by 26% without loss of hardness by introducing SiC w. • The oxidation resistance of HEBs was greatly enhanced due to the addition of SiC whiskers. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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