Enhanced Hardness in High‐Entropy Carbides through Atomic Randomness,Advanced Theory and Simulations

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Enhanced Hardness in High‐Entropy Carbides through Atomic Randomness
Advanced Theory and Simulations ( IF 2.9 ) Pub Date : 2020-08-13 , DOI: 10.1002/adts.202000111
Yichen Wang ₁ , Tamás Csanádi ₂ , Hangfeng Zhang ₁ , Ján Dusza ₂ , Michael J. Reece ₁ , Rui‐Zhi Zhang ₁

Affiliation

High‐entropy carbides (HECs) are of great interest as they are promising candidates for ultra‐high‐temperature and high‐hardness applications. To discover carbides with enhanced yield strength and hardness, mechanism‐based design approaches are needed. In this study, dislocation core atomic randomness as a mechanism for hardness enhancement is proposed, in which the random interactions between different elements at a dislocation core make it more difficult for the dislocation to slip. The Peierls stress of an

a / 2 ⟨ 1 \bar{1} 0 ⟩ {110}

edge dislocation is calculated based on density functional theory, in which atomic randomness is increased by increasing the number of elements at the dislocation core. The results show that the Peierls stress statistically increases with increasing number of elements, indicating that incorporating more elements is likely to produce higher hardness. Based on this guiding principle, three eight‐cation HECs are fabricated (Ti,Zr,Hf,V,Nb,Ta,X,Y)C (X,Y = Mo,W, Cr,Mo, or Cr,W), the composition of which is guided by ab initio calculations of their formation enthalpy and entropy forming ability. The single‐phase dense ceramics all show high nanoindentation hardness of around 40 GPa. The random interactions between different elements at a dislocation core provide a mechanism for improving the hardness of structural ceramics.

中文翻译：

通过原子随机性提高高熵硬质合金的硬度

高熵碳化物（HEC）备受关注，因为它们是超高温和高硬度应用的有希望的候选者。为了发现具有增强的屈服强度和硬度的碳化物，需要基于机理的设计方法。在这项研究中，提出了位错核原子的随机性作为提高硬度的一种机制，其中位错核上不同元素之间的随机相互作用使位错更难以滑动。Peierls强调

一种 / 2 ⟨ 1个 \bar{1个} 0 ⟩ {110}

边缘位错是根据密度泛函理论计算的，其中通过增加位错核心的元素数量来增加原子无规性。结果表明，Peierls应力随着元素数量的增加而在统计上增加，表明掺入更多元素可能会产生更高的硬度。根据这一指导原则，制造了三个八阳离子HEC（Ti，Zr，Hf，V，Nb，Ta，X，Y）C（X，Y = Mo，W，Cr，Mo或Cr，W），其组成由它们的形成焓和熵形成能力的从头算开始。单相致密陶瓷均显示出约40 GPa的高纳米压痕硬度。位错核心处不同元素之间的随机相互作用为改善结构陶瓷的硬度提供了一种机制。

更新日期：2020-09-23

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