The influence of crystallographic texture and interstitial impurities on the mechanical behavior of zirconium

Development of physically based constitutive models capable of simultaneously describing slip, twinning, and anisotropy requires knowledge of the coincident influence of each on mechanical response. In this article, the influence of interstitial impurities and texture on twinning in zirconium (Zr), in addition to variations in strain rate and temperature, are examined, to probe their effects on substructure evolution and mechanical behavior. The compressive-yield responses of both high-purity (HP) crystal-bar and lower-purity (LP) zirconium were found to depend on the loading orientation relative to the c-axis of the hcp cell, the applied strain rate, which varied between 0.001 and 3500/s, and the test temperature, which varied between 77 and 298 K. The rate of strain hardening in zirconium was seen to depend on the controlling defect-storage mechanism as a function of texture, strain rate, and temperature. The substructure evolution of HP zirconium was also observed to be a function of the applied strain rate and test temperature. The substructure of HP zirconium was seen to display a greater incidence of deformation twinning when deformed at a high strain rate at 298 K or quasi-statically at 77 K.