The tracer diffusion of 95Zr and 95Nb was measured, in β-phase alloys which contained 5.5, 16.3 or 28.1at%Nb, at temperatures ranging from 1035 to 1871K (tables 366 to 372). The experimental data were analyzed in terms of Manning's random alloy model, and the partial correlation factors were calculated as a function of temperature. These factors varied smoothly over the entire temperature range, whereas the diffusivity exhibited a pronounced curvature in Arrhenius plots. A correlation was found to exist between the degree of deviation from Arrhenius behavior of the diffusion coefficients of both components, and the lattice dynamics of the measured phonon dispersions, with regard to their dependence upon the Nb content. The temperature dependence of the isotope effect in Zr diffusion was measured for the 5.5at%Nb alloy. The isotope-effect parameter tended to increase with temperature, and the energy-transfer factor for the alloy was somewhat larger than the corresponding values for pure β-Zr; especially at low temperatures. The data led to the overall conclusion that the vacancy mechanism alone operated within the present temperature range.

C.Herzig, U.Köhler, S.V.Divinski: Journal of Applied Physics, 1999, 85[12], 8119-30

Table 363

Diffusivity of Ni in Zr58Co42 Glass