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 degrees 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, Cu4Ti, Cu4Ti3 and CuTi2. The activation energies required for the growth of these compounds were determined. The diffusion characteristics of Cu4Ti, CuTi and Cu4Ti3 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.