Elastic-plastic deformation and spall fracture of metals at high temperatures

Measurements of the Hugoniot elastic limits and the spall strengths of aluminum, magnesium, polycrystalline zinc, and zinc single crystals of two orientations have been carried out over a wide range of initial temperatures, The initial temperature of samples was varied from room temperature to near the melting point. The free-surface velocity profiles recorded with VISAR have revealed a marked reduction in the spall strength as temperatures approached the melting point, being most pronounced for polycrystalline materials. The spall strength of zinc single crystals has been found to be unexpectedly large along the weakest base plane and is explained by purely elastic compression of these samples at shock loading at least up to 6 GPa peak stress. The Hugoniot elastic limit for the zinc single crystals was found to be approximately constant over the whole temperature range.