Reaction-diffusion between pure Ag and Hf was studied at temperatures ranging from 1070 to 1180K. Two compounds, AgHf and Hf2Ag, were observed in the diffusion zone. It was found that layer growth of the AgHf phase obeyed a parabolic law without incubation time, while the Hf2Ag phase appeared after an incubation time of 120h at 1180K, and was not observed at temperatures below 1150K. The temperature dependence of the interdiffusion coefficient, and the square of the layer growth-rate constant of the AgHf phase, obeyed linear Arrhenius relationships. The activation energy for interdiffusion in the AgHf phase was almost equal to that for its layer growth.

O.Taguchi, Y.Iijima: Journal of Alloys and Compounds, 1995, 226, 185-9