Temperature dependence of spall strength and the effect of anomalous melting temperatures in shock-wave loading

The effects of temperature anomalies in materials subjected to the action of shock waves are studied. The spall failure of aluminum single crystals and polycrystals at various temperatures was experimentally studied in [1]. An analysis of the experimental data for polycrystalline aluminum shows that the breaking strength only weakly changes with temperature when it increases from room temperature to 90% of the melting temperature and, then, drops sharply to zero with a further increase in the temperature. For aluminum single crystals, the effect of anomalously high temperatures was experimentally detected; i.e., their strength remained high in the state where melting was expected during tension. The criterion of incubation time of failure is used to obtain an analytical expression for the temperature dependence of the spall strength of the materials. A new melting criterion, which relates the instant of a phase transition to the melting incubation period, is introduced. This criterion allows one to naturally explain the effect of anomalously high melting temperatures detected during the pulsed action.