Internal friction study of substitutional-Interstitial interaction in niobium-vanadium alloys

Abstract

The effect of a small addition of a substitutional solute to both niobium and vanadium on the oxygen Snoek peak of each metal was investigated by an internal friction technique. A vanadium-oxygen interaction peak was identified in Nb-0.24 at. pct V and Nb-0.50 at. pct V alloys at a temperature which is appreciably higher than that for the oxygen Snoek peak in pure niobium. At oxygen concentrations greater than an oxygen/vanadium ratio of 1, the oxygen Snoek peak appears, thus providing strong evidence for oxygen trapping at vanadium in these alloys. A V-0.50 at. pct Nb alloy, on the other hand, shows no such interaction peak but rather only a somewhat broadened vanadium-oxygen Snoek peak. This is interpreted as indicating that oxygen atoms are not trapped by niobium in the vanadium matrix. The activation enthalpies and time constants for the oxygen relaxation for the peaks have been determined. The observed results are discussed in terms of the elastic and chemical interaction models for substitutional-interstitial solute interactions in a bcc lattice.