The diffusivity of 44Ti in β-phase material was studied by using radio-tracer and serial sectioning methods. The Arrhenius plot exhibited a marked upward curvature. This anomalous behavior was related to an experimentally observed softening of the (2/3)[111] phonon mode, and was explained in terms of a monovacancy mechanism with a temperature-dependent migration enthalpy. The diffusion behavior at 1176 to 1893K could be described by:

D (cm2/s) = 3.5 x 100 exp[-3.4(eV)/kT]

U.Köhler, C.Herzig: Physica Status Solidi B, 1987, 144[1], 243-51