Shock-wave compression and tension of solids at elevated temperatures: superheated crystal states, pre-melting, and anomalous growth of the yield strength
Recent studies of the response of metals and alloys to shock-wave loading at elevated temperatures are summarized. Shock-wave tests have been carried out for metal single crystals, polycrystalline metals of different purity, and for alloys. High resistance to sub-microsecond tensile fracture of single crystals is maintained when melting should start. This is treated as evidence of a superheated solid state reached under dynamic tension. In polycrystalline metals, melting starts earlier at grain boundaries; this is known as the pre-melting phenomenon. As a result, their tensile strength drops to zero on approaching the melting curve. Anomalous growth of the dynamic yield stress was observed for low-strength metals, whereas the yield stress of high-strength alloys decreases with temperature. The different behaviour of metals and alloys is treated in terms of the relationship between the phonon drag of the motion of dislocations and the drag forces created by obstacles.
Journal of Physics Condensed Matter
- Pub Date:
- April 2004