Effects of transition metal elements and O on grain boundary energy and strength of Co by first-principles study

Considering the sigma 5 (210)[001] grain boundary of Co as a model, the influence of transition metals and their coupling with O on the grain boundary energy and strength was investigated by a first-principles-based study. Quantitative characterization was used to explain the transition metal segregation at the grain boundary, and the negative correlation between grain boundary energy and atomic radius was revealed. It has been found that the interaction between the solute and the host atoms at the grain boundary affects the grain boundary strength. Re, W, Os, Cr, Tc, Mo, Ir, Ta, Zr, Ru, Nb, V, Rh, Pt, Pd, and Ni can significantly strengthen the grain boundary, while other transition metals have a weakening effect on the grain boundary. In particular, Cr, Hf, Ta, W, Re, Os, Ir, and Pt can effectively alleviate the weakening of the grain boundary caused by O atoms.