Melting along the Hugoniot and solid phase transition for Sn via sound velocity measurements

Abstract

It is very important to determine the phase boundaries for materials with complex crystalline phase structures to construct their corresponding multi-phase equation of state. By measuring the sound velocity of Sn with different porosities, different shock-induced melting pressures along the solid-liquid phase boundary could be obtained. The incipient shock-induced melting of porous Sn samples with two different porosities occurred at a pressure of about 49.1 GPa for a porosity of 1.01 and 45.6 GPa for a porosity of 1.02, based on measurements of the sound velocity. The incipient shock-induced melting pressure of solid Sn was revised to 58.1 GPa using supplemental measurements of the sound velocity. Trivially, pores in Sn decreased the shock-induced melting pressure. Based on the measured longitudinal sound velocity data, a refined solid phase transition and the Hugoniot temperature-pressure curve's trend are discussed. No bcc phase transition occurs along the Hugoniot for porous Sn; further investigation is required to understand the implications of this finding.

Tantalum sound velocity under shock compression

“…Unfortunately, dynamic phase transitions such as melting in metals, including Fe, Mo, Sn, and Ta, are difficult to discern through changes in slope or discontinuities in either stress-density (P-ρ) or shock velocity-particle velocity (U s -U p ) along the Hugoniot. [7][8][9] Certainly, no such changes are resolved in the currently available Ta U s -U p data, which are remarkably linear. 6,7 A closer examination of U p vs time t may yield subtle signs of phase transitions.…”