Pressure dependence of Ni self-diffusion in NiTi

The volume diffusion of Ni was studied in a nearly equiatomic B2 NiTi compound at 1285 K in the pressure range of 0-0.91 GPa. Our measurements, carried out by the tracer technique, proved that the volume diffusion coefficient is independent of the external pressure, and the evaluated activation volume is close to zero. Results may refer either to the interstitial diffusion mechanism or vacancy-mediated diffusion, indicating that in the latter case the vacancy concentration is pressure independent in the investigated pressure range.