Deformation in Zr–1Nb–1Sn–0.1Fe using stress relaxation technique

Deformation behavior of Zr–1Nb–1Sn–0.1Fe was studied using the stress relaxation technique. Stress relaxation experiments were carried out over a range of temperatures (296–765 K) and for strains up to 0.12. The stress–time data were analyzed to obtain the activation volume and enthalpy. It was found that in the strain rate range of 10−4–10−6 s−1 and in the temperature range of 296–570 K, the activation volume and enthalpy do not vary with strain. From this and the magnitude of the activation volume and its variation with thermal stress, either the Peierls stress or the dislocation–interstitial interaction is the rate controlling short range barrier to dislocation motion. The time independent stress component obtained using decremental unloading technique, called here as the remnant stress, was observed to have a large temperature dependence. By using a relation in which the activation free energy is a function of thermal stress, it was found that, in general, the remnant stress cannot be used to represent the athermal stress.