The tracer diffusion of 181Hf, 95Nb and 95Zr was measured in the body-centered cubic structures of Hf-Nb alloys in order to determine whether the Arrhenius plot for self-diffusion exhibited any curvature; as in the case of body-centered cubic Zr-Nb alloys. In the case of the latter alloys, a continuous change in the diffusion anomaly with respect to self-diffusion in pure body-centered cubic Zr had been found. This reflected the systematic variation in electronic structure which occurred upon alloying group-V with group-VI body-centered cubic transition metals. The classification of self-diffusion in body-centered cubic Hf as normal or anomalous had not been possible because of its existence range of only 485K. The alloying of Hf with Nb stabilized the body-centered cubic structure to lower temperatures and considerably extended its existence range. Because the phonon-related diffusion model predicted self-diffusion in body-centered cubic Hf to lead to curved Arrhenius plots, it was expected that such curvature would be exhibited by the Hf-Nb alloys. However, measurements (tables 118 to 125) yielded straight plots for the present alloys.

P.Knorr, C.Herzig: Journal of Physics - Condensed Matter, 1995, 7[48], 9185-200

Table 119

Diffusivity of 95Nb in Hf-18at%Nb

Table 120

Diffusivity of 181Hf in Hf-10at%Nb