Abstract
We have performed the measurements of the sound velocities of fcc-FeHx and fcc-Fe by using a pulse-echo overlap technique at high pressures and high temperatures at BL04B1. The P-wave velocity (VP) of fcc-FeHx (x~0.4) at approximately 12.0 GPa and 900 K was same as that of fcc-Fe, indicating no hydrogen effect on VP of fcc-Fe under that pressure-, temperature-, and hydrogen-conditions.