Study on Effects of B on Behavior and Properties of Alloying Elements such as Zr on Grain Boundary Segregation of Ni Σ5001（210）Join

The single-element segregation behavior of metallic solute elements X（X =Zr, Hf, Ti, Ta, Nb and W） and non-metallic element B in Ni Σ5 001（210） grain boundary（GB） were studied using the first-principles calculations method.On this basis, the co-segregation of B-X and the effect on GB properties were further investigated. The calculation results show that the segregation ability of alloying elements X in the pure Ni GB is weaker than that of B. Compared with the GB segregation behavior of single-element X, X elements in the containing B GBs have lower segregation energies. Due to the similar atomic properties between Zr and Hf as well as Ta and Nb, they have similar segregation energies and GB energies in the co-segregated GBs. W does not segregate into the pure Ni GB, but it can segregate into the B-presented GB. In terms of stabilizing the Ni GB, B-X co-segregations show a synergistic effect, while they show an antagonistic effect on strengthening the Ni GB. B-W co-segregation has the most remarkable GB strengthening ability, which is due to that W atom loses the least electrons（only 0.73 electron） in the Ni GB. This study provides theoretical reference for the design of nano-crystalline Ni alloys.