The influence of interstitial oxygen and peak pressure on the shock loading behavior of zirconium

The pressure of the (alpha)-(omega) phase transition in zirconium is quantified as a function of interstitial content. The pressure increases with increasing interstitial oxygen content and for the high purity (Zr0) material occurs at 7.1 GPa. Increasing the oxygen content increases the number of octahedral sites occupied; this is postulated to increase the pressure for phase transformation. Deformation behavior and substructural evolution of as-annealed Zr0 zirconium under quasi-static conditions is compared to its response following shock prestraining at 5.8 and 8 GPa. The reload response of Zr0 zirconium shock prestrained to 8 GPa exhibits enhanced hardening, while specimens shocked to 5.8 GPa do not when compared to quasi-static constitutive behavior.