The grain boundary radio-tracer diffusion of 207Bi in polycrystalline Cu was measured in the Harrison B (1198 to 843K) and C (659 to 536K) kinetic regimes. In the B-regime, the product, P = sδDgb (where s was the segregation factor and δ the grain boundary width), obeyed the Arrhenius relationship:

P (m3/s) = 6.6 x 10-12exp[-102.8(kJ/mol)/RT]

Measurements in the C-regime yielded the temperature dependence of the Bi grain boundary diffusion coefficient in Cu:

Dgb (m2/s) = 2.4 x 10-1exp[-156.2(kJ/mol)/RT]

By assuming that δ was equal to about 5 x 10−10m, the segregation factor was determined, in the limit of very dilute solution, to obey an Arrhenius law with a pre-exponential factor of 0.054 and an enthalpy of 53.4kJ/mol.

S.Divinski, M.Lohmann, C.Herzig: Acta Materialia, 2004, 52[13], 3973-82

Table 39

Grain-Boundary Diffusivity of Au in Cu