Examining the variation in melt entropy with pressure using shock melting

The variation in the melting point of metals is of significant technical and theoretical importance, and constitutes a major area of research in high pressure physics. Recent advances in time-resolved diffraction and pyrometry are enabling experiments that constrain the temperature and density through dynamic loading. The extent of the two-phase region along the Hugoniot provides measurements of the location of the solidus and liquidus at pressure. Coupled with measurements of compressibility (i.e. sound speed), it is possible to constrain the transition entropy of a first order phase transition. In this presentation, recent measurements on Sn and Al (XRD, pyrometry, sound speed) will be used to motivate an approach to constrain the melt entropy and temperature at Mbar pressures.