Melting of iron under core conditions

Abstract

Melting in iron has been detected in shock wave experiments. Release wave velocities are determined using the overtaking rarefaction technique. Upon melting the shear modulus becomes zero leading to a decrease in the acoustic wave velocity behind the shock front. Two velocity discontinuities have been detected: (1) 200 ± 2 GPa at a calculated temperature of about 4000K and (2) 250 ± 10 GPa at a calculated temperature of about 5500‐6000K. The evidence indicates that the ε‐γ transition occurs at 200 GPa and that γ iron melts near 250 GPa along the iron Hugoniot.