Diffusion-induced recrystallization in the Cu(Pd) system at complete solid-solution temperatures

Owing to annealing at complete solid-solution temperatures around 1,000 K, Pd can quickly penetrate into Cu due to diffusion-induced recrystallization (DIR). To examine this penetration behavior, DIR in the Cu(Pd) system was experimentally observed in the present study. A diffusion bonding technique was used to prepare polycrystalline Cu/Pd/Cu diffusion couples. The diffusion couple was isothermally annealed at temperatures of T = 923–1,023 K for various times up to t = 176 h. During annealing, a region alloyed with Pd is produced in Cu from the Cu/Pd interface due to DIR. The concentration of Pd on the Pd-rich side in the DIR region remains almost constant independent of the annealing time but increases with increasing annealing temperature. On the other hand, the mean thickness of the DIR region increases with increasing annealing time. The growth rate of the DIR region is a monotonically increasing function of the annealing temperature. The experimental findings of the kinetics study were quantitatively analyzed using a mathematical model. The analysis satisfactorily reproduces the overall growth behavior of the DIR region.