Du Zhenyu, Zuo Jie, Bao Nanyun, Yang Mingli, Jiang Gang, Zhang Li
Institute of Atomic and Molecular Physics, Sichuan University Chengdu 610065 China
College of Computer Science, Sichuan University Chengdu 610065 China.
RSC Adv. 2019 May 28;9(29):16447-16454. doi: 10.1039/c9ra03055g. eCollection 2019 May 24.
Ta addition has considerable effects on the microstructures and mechanical performances of CoCrFeNi alloy systems. Structure search with the special quasirandom structure method and structure identification with first-principles calculations were carried out to investigate the structural, thermodynamic and mechanical properties of CoCrFeNiTa ( = 0.0-1.0) high-entropy alloys in the fcc and bcc lattice frameworks. The predicted lattice parameters of identified structures are in agreement with available experiments. Phase transition between the fcc and bcc lattices was predicted for the lowest-energy structures with increasing Ta content. The predicted temperature dependence of specific heat capacity for the identified structures matches well with the Dulong-Petit, Kepp and Debye Models. Both vibration and configuration entropy contribute to the stabilization of alloy systems, while the latter is about 2-3 times greater than the former. The elastic constants and moduli vary with composition and phase structure. Ta atoms have preference to some atoms like Ni, and form relatively strong bonds with adjacent atoms. The introduction of Ta promotes the electron localization and favors the formation of mixed structures.
Ta的添加对CoCrFeNi合金体系的微观结构和力学性能有显著影响。采用特殊准随机结构方法进行结构搜索，并通过第一性原理计算进行结构识别，以研究fcc和bcc晶格框架中CoCrFeNiTa（= 0.0 - 1.0）高熵合金的结构、热力学和力学性能。所识别结构的预测晶格参数与现有实验结果一致。随着Ta含量增加，预测最低能量结构会发生fcc和bcc晶格之间的相变。所识别结构的预测比热容随温度的变化与杜隆 - 珀蒂、凯普和德拜模型吻合良好。振动熵和组态熵都有助于合金体系的稳定，而后者比前者大约大2 - 3倍。弹性常数和模量随成分和相结构而变化。Ta原子倾向于与某些原子如Ni结合，并与相邻原子形成相对较强的键。Ta的引入促进了电子局域化，并有利于混合结构的形成。
