Compositional phase stability in medium-entropy and high-entropy Cantor-Wu alloys from an ab initio all-electron Landau-type theory and atomistic modeling
Compositional phase stability in medium-entropy and high-entropy Cantor-Wu alloys from an ab initio all-electron Landau-type theory and atomistic modeling
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DOI：
10.1103/physrevb.105.115124
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发表时间：
2022-03
影响因子：
3.7
通讯作者：
Christopher D. Woodgate;J. Staunton
中科院分区：
文献类型：
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作者：
Christopher D. Woodgate;J. Staunton
我们描述了在早期工作中导出的第一性原理理论的实现和分析，该理论针对多组分合金的吉布斯自由能展开中的主要项，以表征潜在的组成相的有序参数。该理论包括通过改变晶格位置上的原子占据而重新排列电荷和其他电子的影响。除了均匀无序相中原子短程有序的严格描述之外，还可以计算适合多组分设置中原子建模的成对相互作用参数。从我们对 Cantor-Wu 合金、NiCo、NiCoCr、NiCoFeCr 和 NiCoFeMnCr 的指示性系列的研究中，我们发现相互作用不能很好地近似为伪二元或限制在最近邻范围内。我们计算的有序-无序转变温度较低，与实验观察结果一致，有序性质主要由 Ni、Co 和 Cr 之间的相关性决定，而 Fe 和 Mn 相互作用较弱。进一步的原子建模表明，这些多组分系统不存在真正的单相低温基态。相反，单相固溶体通过大的构型熵和 Fe、Mn 稀释效应而在低温下保持稳定。我们的方法的计算成本效益使其成为进一步探索多元合金空间的良好候选者。
We describe implementation and analysis of a first-principles theory, derived in an earlier work, for the leading terms in an expansion of a Gibbs free energy of a multi-component alloy in terms of order parameters that characterize potential, compositional phases. The theory includes effects of rearranging charge and other electronics from changing atomic occupancies on lattice sites. As well as the rigorous description of atomic short-range order in the homogeneously disordered phase, pairwise interaction parameters suited for atomistic modelling in a multicomponent setting can be calculated. From our study of an indicative series of the Cantor-Wu alloys, NiCo, NiCoCr, NiCoFeCr, and NiCoFeMnCr, we find that the interactions are not approximated well either as pseudobinary or restricted to nearest neighbour range. Our computed order-disorder transition temperatures are low, consistent with experimental observations, and the nature of the ordering is dominated by correlations between Ni, Co, and Cr, while Fe and Mn interact weakly. Further atomistic modelling suggests that there is no true single-phase low-temperature ground state for these multicomponent systems. Instead the single-phase solid solution is kept stable to low temperatures by the large configurational entropy and the Fe, Mn dilution effects. The computationally cost-effectiveness of our method makes it a good candidate for further exploration of the space of multicomponent alloys.