Surface energies and relaxation of NiCoCr and NiFeX (X = Cu, Co or Cr) equiatomic multiprincipal element alloys from first principles calculations
Surface energies and relaxation of NiCoCr and NiFeX (X = Cu, Co or Cr) equiatomic multiprincipal element alloys from first principles calculations
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DOI：
10.1088/1361-651x/ac3e07
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发表时间：
2021-11
影响因子：
1.8
通讯作者：
Wei Li;Xianghe Peng;A. Ngan;J. El-Awady
中科院分区：
文献类型：
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作者：
Wei Li;Xianghe Peng;A. Ngan;J. El-Awady
采用第一性原理计算了NiCoCr和NiFeX（X = Cu，Co或Cr）等原子多主元素合金（MPEAs）中未重构低指数面（001），（011）和（111）的能量和弛豫.采用广义梯度近似下的投影缀加波方法，对由特殊准随机超原胞表示的12层板进行了计算。虽然实验预测是不可用的比较，计算的表面能同意相当不错，从热力学模型和键切模型。此外，计算还揭示了一个重要的表面结构，即除了NiFeCr合金的（001）面外，最上面的表面层处于收缩状态，下面的表面层处于伸展状态，从下面的表面层开始，体间距逐渐恢复。此外，表面收缩在（011）平面上最明显，相对于体间距约为4%-10%。这里提出的结果可以提供在这些等原子MPEAs的腐蚀，催化活性和断裂性能等表面控制的现象的理解。
First principles calculations of the energies and relaxation of unreconstructed low-index surfaces, i.e. (001), (011) and (111) surfaces, in NiCoCr and NiFeX (X = Cu, Co or Cr) equiatomic multi-principal element alloys (MPEAs) are presented. The calculations were conducted for 12-layer slabs represented by special quasi-random supercells using the projector augmented wave method within the generalized gradient approximation. While experimental predictions are unavailable for comparison, the calculated surface energies agree fairly well with those from thermodynamic modeling and a bond-cutting model. In addition, the calculations unveil an important surface structure, namely, that the topmost surface layer is in contraction except for the (001) surface of NiFeCr alloy, the next layer below is in extension, and the bulk spacing is gradually recovered from the subsequent layers down. Additionally, the surface contraction is the most pronounced on the (011) plane, being about 4%–10% relative to the bulk spacings. The results presented here can provide an understanding of surface-controlled phenomena such as corrosion, catalytic activities and fracture properties in these equiatomic MPEAs.