Grain boundary diffusion and segregation of Ge in Cu: Radiotracer measurements in different kinetic regimes

Abstract

Abstract Grain boundary (GB) solute diffusion of Ge in Cu polycrystals was systematically investigated by the radiotracer serial sectioning technique using 68Ge and 71Ge isotopes. The diffusion measurements were carried out under conditions of Harrison's B- (923–626 K) and C- (576–451 K) type diffusion regimes. In the B-type diffusion regime, the triple product P = sδDgb (s is the segregation factor and δ the GB width) was found to follow the Arrhenius law P = 4.0 × 10−16 × exp(–58.6 kJ mol−1/RT) m3s−1, where R is the universal gas constant and T the temperature. Measurements in the C-regime directly yielded the GB diffusion coefficient Dgb, Dgb = 2.8 × 10−6 × exp(–84.8 kJ mol−1/RT) m2s−1. Combining the obtained P and Dgb values and assuming δ ≅ 5 × 10−10 m, the GB segregation factor for Ge in Cu was determined to follow an Arrhenius dependence s = 0.29 exp(26 kJmol−1/RT). The determined segregation coefficients s are discussed together with previous results on solute segregation in Cu and Ag, and it is c...