The observations of grain-boundary segregation of Bi in Cu bicrystals were analyzed. According to equilibrium grain boundary segregation (EGS) model and non-equilibrium grain-boundary segregation (NGS) model, resp...The observations of grain-boundary segregation of Bi in Cu bicrystals were analyzed. According to equilibrium grain boundary segregation (EGS) model and non-equilibrium grain-boundary segregation (NGS) model, respectively, the segregation kinetics of isothermal annealing at 500 °C and that of isochronal annealing for 24 h of Bi in Cu bicrystals were investigated. By qualitative analysis and quantitative analysis, it is concluded that the grain-boundary segregation of Bi agrees well with the theory of NGS. Based on the kinetics model of NGS, some parameters that are useful to predicting and controlling the Bi-induced embrittlement in Cu alloys are calculated as follows:the diffusion coefficient of Bi-vacancy complexes Dc=7.8×10^-5exp[-1.46/(kT)];the apparent diffusion coefficient of Bi atoms Di^A=7.66×10^at+bexp[–1.76/(kT)], where a=8.45×10^-8 and b=-13.37.展开更多
基金Project(51001011)supported by the National Natural Science Foundation of ChinaProject(141043)supported by the Fok Ying-Tong Education Foundation,ChinaProject(FRF-TP-12-042A)supported by the Fundamental Research Funds for the Central Universities,China
文摘The observations of grain-boundary segregation of Bi in Cu bicrystals were analyzed. According to equilibrium grain boundary segregation (EGS) model and non-equilibrium grain-boundary segregation (NGS) model, respectively, the segregation kinetics of isothermal annealing at 500 °C and that of isochronal annealing for 24 h of Bi in Cu bicrystals were investigated. By qualitative analysis and quantitative analysis, it is concluded that the grain-boundary segregation of Bi agrees well with the theory of NGS. Based on the kinetics model of NGS, some parameters that are useful to predicting and controlling the Bi-induced embrittlement in Cu alloys are calculated as follows:the diffusion coefficient of Bi-vacancy complexes Dc=7.8×10^-5exp[-1.46/(kT)];the apparent diffusion coefficient of Bi atoms Di^A=7.66×10^at+bexp[–1.76/(kT)], where a=8.45×10^-8 and b=-13.37.