Grain boundary diffusion and segregation of Bi in Cu: radiotracer measurements in B and C diffusion regimes Original Research Article

Grain boundary (GB) radiotracer diffusion of 207Bi in polycrystalline Cu was measured in Harrisonʹs B (1198–843 K) and C (659–536 K) kinetic regimes. In the B regime the triple product P=s·δ·Dgb (where s is the segregation factor and δ the GB width) was found to obey the Arrhenius law P=6.6×10−12×exp (−102.8 kJ mol−1/RT) m3 s−1. The measurements in the C regime yielded the temperature dependence of the Bi GB diffusion coefficient Dgb in Cu, Dgb=0.24×exp (−156.2 kJ mol−1/RT) m2 s−1. Assuming that δ≅5×10−10 m the segregation factor s of Bi in Cu was determined in the limit of very dilute solute concentration to follow an Arrhenius dependence s=s0exp(−ΔHs/RT) with the pre-exponential factor s0=0.054 and the segregation enthalpy ΔHs=−53.4 kJ mol−1.