Melting of metals above 100 GPa

The optical analyzer technique was used to determine the pressure at which shock-compressed iron, tantalum, and aluminum can no longer support a longitudinal elastic wave. At this pressure the release-wave velocity drops to a value consistent with a calculated bulk sound velocity, indicating partial melting. At higher shock pressures, the bulk sound velocities follow a constant rhoγ model, where γ is the Grueneisen parameter. With these measurements melting on the Hugoniot was identified, and three metals were calibrated as drivers for similar experiments on other materials. 17 references, 6 figures