In order to obtain information on the diffusion mechanism in body-centered cubic transition metals, the pressure dependence of the diffusivity of 95Zr was measured in this equi-atomic alloy at 1003 or 1493K, using pressures of up to 1440MPa (table 165). The activation volumes at 1003 and 1493K were 0.31 and 0.35, respectively. These positive values conflicted with previously reported negative values, but agreed very well with the activation volume for self-diffusion in -Ti. Within experimental error, the activation volume was independent of the temperature, thus indicating that only 1 diffusion mechanism operated in spite of the markedly curved Arrhenius plots for 95Zr and 44Ti diffusion in this alloy. It was concluded that the present results confirmed the operation of a monovacancy mechanism in group-IVa body-centered cubic metals.

M.Büscher, C.Herzig, U.Köhler, H.Mehrer, W.Lojkowski: Physica Status Solidi B, 1992, 174[2], 347-57

Table 165

Diffusivity of Zr in TiZr as a Function of Pressure