Pressure dependence of Ni self-diffusion in NiTi

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