The diffusion path in NiCu-Ti ternary diffusion couples

The formation and growth of intermetallic compounds by reactive diffusion between model alloy Ni30-Cu70 (composition given in at.%) and high purity Ti was investigated at a temperature of 850 °C using bulk diffusion couples for 100 h. Only three stable intermediate compounds of the Ni30Cu70-Ti system were formed in the diffusion reaction zone in the sequence Ti2Cu, TiNi and τ1 (Ti(Ni1−xCux)2. Moreover, on the microstructure the two phase zone consisting of TiNi2Cu + Ni30Cu70 can be observed. Next to the experimental description, a model determining the diffusion path in a multiphase system was proposed. The proposed model is based on mass conservation law and geometrical lemmas, that allow for the determination of the unique diffusion path in complicated systems.