Estimation of the Critical Point Parameters of the Liquid–Vapor Phase Transition of Metals Using Experiments on the Isentropic Expansion of Shock-Compressed Porous Samples

The isentropic expansion of shock-compressed porous metals (Cu, W, Nb) are experimentally studied, and the experimental results are used to determine their thermodynamic parameters and electrical conductivity. These results allow us to conclude that some porous metals after shock compression and expansion have a two-phase structure. The presence of an additional phase at the isentropic expansion of these metals significantly changes the character of evaporation and the critical point parameters of the liquid–vapor phase transition that are estimated using experiments on the isentropic expansion of shock-compressed porous metals. In addition, the formation of the two-phase structure explains the large difference between the critical point parameters estimated by different methods for a large group of metals (U, W, V, Co, Mo, Ta, etc.).