Measurement of diffusion coefficients of interstitial impurities in Zr – 1 wt. % Nb alloy by internal friction method

Abstract

In alloys with a GPU lattice, it is possible to observe a relaxation of the Snukovsky type if there is a certain amount of substitution impurities in it. However, it is impossible to calculate the diffusion coefficients of the introduction impurities by the measured relaxation time by analogy with BCC alloys, just because of the possible interaction with substitution atoms. However, in some cases, if reliable diffusion data are available for an alloy close in composition to the studied one, the relaxation time can be calculated from the ratio τr = τr0·exp(Hm/RTm), where Hm, Tm are the parameters of the relaxation maximum of the impurity from the experiment, and τr0 can be calculated from the formula D0 = c02/(16·τr0) for the GPU lattice, taking D0 from the corresponding diffusion expert data. In this way, the diffusion coefficients of the introduction impurities in the alloy Zr – 1 wt. % Nb are calculated for several states of samples.