Kinetics of phase formation during interdiffusion in the ternary system Ni-Cu-5 at.% Sn

The evolution of concentration profiles during interdiffusion in three-layer samples Cu(5 at.% Sn)-Ni(5 at.% Sn)-Cu(5 at.% Sn) with inert markers has been studied by the methods of optical microscopy and SEM with X-ray microprobe analysis. 'Up-hill' diffusion of Sn and formation of two-phase zones with periodically changing precipitates of (NiCu)₃Sn and a metastable solution have been found. Interrelation between the Kirkendall and Frenkel effects and 'up-hill' Sn diffusion has been discussed.