Uncovering the influence mechanism of nonmetallic atoms on the mechanical properties of Ni3Co alloy

Abstract

The introduction of solute atoms has a critical effect on the mechanical properties of nickel-cobalt alloys. In the present study, we first prepare the Ni3Co alloy coating by electrodeposition and perform structural characterization. The results show that the alloy has a single-phase FCC structure with no other distinct characteristic peaks. On this basis, we established the L12-Ni3Co crystal model, and detailed analysis of the mechanism of varying nonmetallic atoms (C, B, N, P) on the elastic properties of the alloy by first-principle calculation. The results of mechanical and thermal performance parameters such as elastic modulus, hardness and Debye temperature show that compared with the other three elements, the strengthening effect of N atom is the best, especially when in the interstitial site, the strengthening effect of smaller non-metallic atoms is more significant. Moreover, the doped systems are both elastic and sound velocity anisotropic, and the strength of the alloy is approximately positively correlated with the degree of anisotropy. The analysis of the electronic structure shows that the introduction of interstitial atoms leads to a transformation of the local bonding properties, and the strengthening effect can be attributed to the strong covalent interaction between them and the Ni or Co atoms.