A marked enhancement of interdiffusion was observed in Cu-Ni diffusion couples when the samples were heated under high (about 5GPa) H pressures. The interdiffusion coefficients which were measured at temperatures of between 600 and 800C were increased by about 104 times at the Ni-rich end (figure 3), and by about 10 times at the Cu-rich end. The results were explained in terms of super-abundant vacancy formation in the presence of interstitial H atoms.

Hydrogen-Induced Enhancement of Interdiffusion in Cu-Ni Diffusion Couples E.Hayashi, Y.Kurokawa, Y.Fukai: Physical Review Letters, 1998, 80[25], 5588-90