First-principles study of the effect of solute co-segregation on Y {101¯1} twin boundary

The segregation behavior of solute at grain boundaries (GBs) will change the macroscopic properties of GBs, which in turn affect the properties of the material. In this study, we systematically investigate the effects of the segregation behavior of solute X (Nb, Mo, Ru, Ag, Hf, W, Re, Pt, Bi) near the Y {10$\overline{1}$1} twin boundaries (TBs), as well as the effect of X-Z co-segregation behavior on the stability and strength of the TBs based on the first-principles calculations. The results show that the solute segregation of Ru and Pt can improve the stability and strength of TB, but the contribution of Ru in stabilizing TB and Pt in strengthening TB is relatively limited. Based on the Rice-Wang model and combined with grain boundary energy, strengthening energy, and first-principles computational tensile test, it is found that Ru-Bi co-segregation significantly enhances the strength and stability of TB. The corresponding charge density difference and density of electronic state analysis show that Ru-Bi co-segregation significantly enhances the bond cooperation between atoms near the grain interface and reveals the microscopic mechanism of strengthening the TB from the electronic structure level. The aim of this study is to provide theoretical support for the optimal design and property regulation of yttrium-based alloys.