Alloys which contained up to 8at%Si were studied at 900 to 1150K by using semi-infinite couples and Kirkendall markers (table 104). The tracer diffusivity of Cu in pure Cu, and in alloys which contained up to 1.8at%Si, was also studied at 1130K by using the serial sectioning method. It was found that a non-linear enhancement of Cu diffusivity was caused by adding Si. The first- and second-order enhancement factors for solvent diffusivity were deduced to be 19.4 and 188, respectively. The Gibbs free energy of binding between a vacancy and a Si atom was estimated to be -11.8kJ/mol at 1130K. By using self-diffusivity data for pure Cu, and by extrapolating diffusion data on Cu-Si alloys to infinite dilution, the vacancy flow factor in the Cu-Si system at 1130K was deduced to be -0.62. Overall, the results indicated that there was a weak interaction between a vacancy and a Si atom in Cu.

Y.Iijima, Y.Wakabayashi, T.Itoga, K.Hirano: Materials Transactions A, 1991, 32[5], 457-64

Table 105

Interdiffusion Parameters for Cu-Si Alloys

Table 106

Diffusion of 64Cu in Cu-15at%Sn