Measurements of sound velocities in shock-compressed tantalum and LY12 Al

Reverse-impact method used to measure the high-pressure sound velocity in shock-compressed metals was described. Two reverse-impact set-ups, Ta/LY12 Al buffer/LiF window and Ta/LiF window, were used to measure the sound velocity in shock-compressed Ta over the range of 110~131 GPa . Measured longitudinal sound velocities in Ta are consistent with the data reported by Brown J M, et al. No significant effects of LY12 Al buffer on the measurement uncertainty of sound velocity were found because of little difference in impedance between LY12 Al and LiF. The longitudinal sound velocities of LY12 Al buffer were determined at 110 GPa and 131 GPa. The data combining with those reported by McQueen R G show that the longitudinal sound velocities in LY12 Al decrease gradually to bulk sound velocities with pressure over the range of 125~150 GPa.