Spall Strength of Shock-Heated Zirconium and Phase Diagram of Its High-Pressure Polymorphic Modification

Spall strength of zirconium heated by a strong shock wave to thousand-degree temperatures and that underwent transformations into denser polymorphic modifications was determined. Pressure profiles at the sample–soft barrier boundary were measured in spall experiments under flat one-dimensional loading. The equations of state of three polymorphic modifications of zirconium were constructed in the pressure range up to 50 GPa. Thermodynamic states of zirconium, which were calculated under conditions of experiments, in combination with results of measurements of pressure profiles, made it possible to determine the spall strength of zirconium heated in the shock compression–unloading cycle. The spall strength of zirconium was –2.8(7) GPa at 1027(70) K. Experimental pressure profiles were analyzed using the results of mathematical modeling of the performed experiments.