Investigation of near-critical states of molybdenum by method of isentropic expansion

In this work release isentropes of shocked porous molybdenum were investigated. Samples with an initial porosity m = rho(0)/rho = 1.4 and 3.1 were studied to achieve near-critical entropy states of metal after shock compression. Compressed samples were expanded into helium with different initial pressures. The brightness temperature of the metal and the helium shock wave velocity were measured with a fast multichannel pyrometer. The helium shock wave velocity was used to determine the final pressure (P(S)) of expansion of the metal and the velocity of metal expansion (W(S)). Location of peculiarities on the P(S)-W(S) and P(S)-T(P) curves of the isentropes gives the location of their entrance into the two-phase region. Estimation of the molybdenum critical temperature and pressure was carried out on the basis of the experimental data.