Short-range order and compositional phase stability in refractory high-entropy alloys via first-principles theory and atomistic modeling: NbMoTa, NbMoTaW, and VNbMoTaW
Short-range order and compositional phase stability in refractory high-entropy alloys via first-principles theory and atomistic modeling: NbMoTa, NbMoTaW, and VNbMoTaW
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DOI：
10.1103/physrevmaterials.7.013801
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发表时间：
2022-11
影响因子：
3.4
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
使用全电子，第一性原理，朗道型理论，我们研究的性质短程有序和组成相稳定性等原子耐火高熵合金，NbMoTa，NbMoTaW，VNbMoTaW。我们还调查选定的二元子系统，以提供深入了解的物理机制驱动秩序。我们的方法直接检查的固溶体的短程顺序，推断无序/有序转变，并提取适合扩散相变的原子模型的参数。我们发现这些材料中的化学物种之间的关系，促进有序的倾向层次。最主要的是3d元素V与其他4d和5d元素之间的相对原子大小差异，这驱动了类似B32的顺序。对于V不存在的系统，排序由价态填充的差异决定;等电子的元素对与低温保持弱相关，而具有价差的元素对呈现B2-样顺序。我们估计在VNbMoTaW的有序-无序转变温度是足够高的，我们建议，在这种材料中的SRO可能是实验观察。
Using an all-electron, first principles, Landau-type theory, we study the nature of short-range order and compositional phase stability in equiatomic refractory high entropy alloys, NbMoTa, NbMoTaW, and VNbMoTaW. We also investigate selected binary subsystems to provide insight into the physical mechanisms driving order. Our approach examines the short-range order of the solid solutions directly, infers disorder/order transitions, and also extracts parameters suitable for atomistic modelling of diffusional phase transformations. We find a hierarchy of relationships between the chemical species in these materials which promote ordering tendencies. The most dominant is a relative atomic size difference between the 3d element, V, and the other 4d and 5d elements which drives a B32-like order. For systems where V is not present, ordering is dominated by the difference in filling of valence states; pairs of elements which are isoelectronic remain weakly correlated to low temperatures, while pairs with a valence difference present B2-like order. Our estimated order-disorder transition temperature in VNbMoTaW is sufficiently high for us to suggest that SRO in this material may be experimentally observable.