Diffusion characteristics in the Cu–Ti system

The formation and growth of intermetallic compounds by diffusion reaction of Cu and Ti were investigated in the temperature range 720–860°C using bulk diffusion couples. Only four, out of the seven stable intermediate compounds of the Cu–Ti system, were formed in the diffusion reaction zone in the sequence CuTi, Cu 4 Ti, Cu 4 Ti 3 and CuTi 2 . The activation energies required for the growth of these compounds were determined. The diffusion characteristics of Cu 4 Ti, CuTi and Cu 4 Ti 3 and Cu(Ti) solid solution were evaluated. The activation energies for diffusion in these compounds were 192.2, 187.7 and 209.2 kJ mol −1 respectively, while in Cu(Ti), the activation energy increased linearly from 201.0 kJ mol −1 to 247.5 kJ mol −1 with increasing concentration of Ti, in the range 0.5–4.0 at.%. The impurity diffusion coefficient of Ti in Cu and its temperature dependence were also estimated. A correlation between the impurity diffusion parameters for several elements in Cu matrix has been established.