摘要
For NiAI intermetallic compound with B2 structure, there is still no calculation combining models of sin- gle and multiple layers while using the same basic set. Furthermore, some recently proposed criteria for brittleness and toughness have not been used to analyze its deformation behavior. Thus, first-principles calculation was applied to comprehensively study the elastic properties, ideal strength, generalized stacking fault energy and surface energy of B2-NiA1 intermetallic compound. The results suggest that calculations based on the current basic set give more accurate lattice parameters and elastic moduli. The Pugh criterion and Cauchy pressure cannot be used to interpret the intrinsic brittleness of NiAI. In comparison, the ductility parameter based on the strain energy under elastic instability and ZCT and Rice criteria based on generalized stacking fault energy and surface energy successfully identify the intrinsic brittleness of the NiA1 intermetallic compound. The reason why [111] slip always occurs in the defor- mation along [100] direction was clarified by examining the critical value for brittle-ductile transition. The results of density of state indicate shear deformation has less impact on structural stability, and the change of charge density difference implies that 〈001〉 shear induces more intensive redistribution of charge density, which is well correlated to the brittleness and deformation behavior of NiAI intermetallic comnound.
For NiAI intermetallic compound with B2 structure, there is still no calculation combining models of sin- gle and multiple layers while using the same basic set. Furthermore, some recently proposed criteria for brittleness and toughness have not been used to analyze its deformation behavior. Thus, first-principles calculation was applied to comprehensively study the elastic properties, ideal strength, generalized stacking fault energy and surface energy of B2-NiA1 intermetallic compound. The results suggest that calculations based on the current basic set give more accurate lattice parameters and elastic moduli. The Pugh criterion and Cauchy pressure cannot be used to interpret the intrinsic brittleness of NiAI. In comparison, the ductility parameter based on the strain energy under elastic instability and ZCT and Rice criteria based on generalized stacking fault energy and surface energy successfully identify the intrinsic brittleness of the NiA1 intermetallic compound. The reason why [111] slip always occurs in the defor- mation along [100] direction was clarified by examining the critical value for brittle-ductile transition. The results of density of state indicate shear deformation has less impact on structural stability, and the change of charge density difference implies that 〈001〉 shear induces more intensive redistribution of charge density, which is well correlated to the brittleness and deformation behavior of NiAI intermetallic comnound.
基金
the financial supports from the National Natural Science Foundation of China (Grant No. 51771118, U1760110, and 51627802)
the Science and Technology Committee of Shanghai Municipality (Grant No. 17QC1400800 and 16DZ2260602)
the State Key Laboratory of Solidification Processing in NWPU (Grant No. SKLSP201732)
