The bulk diffusion of Ni was studied in almost-equiatomic samples of the B2 compound, at 1285K, under pressures ranging from 0 to 0.91GPa. The measurements were carried out by using the tracer technique, and it was proved that the volume diffusion coefficient was independent of the external pressure; with an estimated activation volume which was close to zero. The results supported both interstitial diffusion and vacancy-mediated diffusion. In the latter case, the vacancy concentration had to be pressure-independent within the investigated pressure range.

Pressure Dependence of Ni Self-Diffusion in NiTi. G.Erdélyi, Z.Erdélyi, D.L.Beke, J.Bernardini, C.Lexcellent: Physical Review B, 2000, 62[17], 11284-7