Site Preference of the Alloying Additions on Mechanical Properties of L12 Ni3Co Alloys

The site preferenceSite preference and alloying effects of transitionTransition metal elements M (M = W, Nb, Ta) on mechanicalMechanical properties propertiesProperties of L12 NiCo-based alloys are investigated by density functional theoryDensity functional theory . The formation enthalpy (ΔHf) and substitution formation enthalpy ($$ E_{\text{site}} $$) are calculated to prediction the site preferenceSite preference of elements M. The results indicate that the three elements all tend to replace Ni site. The mechanical propertiesMechanical properties (elastic propertiesProperties and hardnessHardness ) calculations show that the alloying elements deteriorate the ductility and remarkably improve the hardnessHardness of the Ni3Co alloys. Ni23NbCo8 possesses the lowest ductility and the highest hardnessHardness . Ni23TaCo8 displays the highest shear modulus (G) and Young’s modulus (E). The anisotropic factorsAnisotropic factors , 3D directional Young’s modulus, predict Ni23MCo8 alloys are all anisotropic materials, and the degree of anisotropyAnisotropy is small. Further analyses on electron localization function (ELF) demonstrate that mechanicalMechanical properties propertiesProperties are closely connected with the bonding nature of the alloys.