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Enhanced Hardening Effects on Molybdenum-Doped WB2 and WB2–SiC/B4C Composites
Chemistry of Materials ( IF 7.2 ) Pub Date : 2022-06-14 , DOI: 10.1021/acs.chemmater.2c00386
Lisa E. Pangilinan 1 , Shanlin Hu 1 , Christopher L. Turner 1 , Jinyuan Yan 2 , Abby Kavner 3 , Reza Mohammadi 4 , Sarah H. Tolbert 1, 5, 6 , Richard B. Kaner 1, 5, 6
Affiliation  

Tungsten diboride (WB2) solid solutions with increasing molybdenum (Mo) substitution were synthesized by resistive arc-melting from the pure elements and characterized for their mechanical properties. The WB2-type structure is maintained up to 30 atomic percent (at%) Mo substitution. W0.70Mo0.30B2 achieved a maximum Vickers hardness of 45.7 ± 2.5 GPa at 0.49 N, resulting in the hardest WB2 solid solution to date. In agreement with this fact, high-pressure radial diffraction studies indicate that substitution of Mo into WB2 strengthens metal–boron bonding, as the solid solution supports high differential stress and has a bulk modulus of 355 ± 2 GPa. WB2 and W0.70Mo0.30B2 composites were then synthesized with increasing additive content (0–30 wt%) of B4C or SiC to study extrinsic hardening effects through multiphase formation. These composites show extrinsic effects on the Vickers hardness because of secondary-phase precipitation. While WB2–30 wt% B4C exhibited the highest hardness (53.8 ± 6.0 GPa at 0.49 N), WB2–30 wt% SiC demonstrated the slowest oxidation rate. This work offers new insights for tailoring transition-metal boride systems with optimized hardness, grain morphology, and thermal stability.

中文翻译:

增强钼掺杂 WB2 和 WB2–SiC/B4C 复合材料的硬化效果

通过电阻电弧熔炼纯元素合成了钼(Mo)取代度增加的二硼化钨(WB 2)固溶体,并对其机械性能进行了表征。WB 2型结构保持高达30原子百分比(at%)的Mo取代。W 0.70 Mo 0.30 B 2在 0.49 N 时达到了 45.7 ± 2.5 GPa 的最大维氏硬度,从而产生了迄今为止最硬的 WB 2固溶体。与这一事实一致,高压径向衍射研究表明,将 Mo 置换到 WB 2中可增强金属-硼键合,因为固溶体支持高差异应力并具有 355 ± 2 GPa 的体积模量。世界银行然后合成2和 W 0.70 Mo 0.30 B 2复合材料,增加 B 4 C 或 SiC 的添加剂含量(0-30 wt%),以研究通过多相形成的外在硬化效应。由于二次相沉淀,这些复合材料对维氏硬度表现出外在影响。WB 2 –30 wt% B 4 C 表现出最高的硬度(0.49 N 时为 53.8 ± 6.0 GPa),WB 2 –30 wt% SiC 表现出最慢的氧化速率。这项工作为定制具有优化硬度、晶粒形态和热稳定性的过渡金属硼化物系统提供了新的见解。
更新日期:2022-06-14
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