Shock temperatures and the melting point of iron

Abstract

New measurements of the ratio of Fe to LiF and Al2O3 anvil thermal diffusivities are used to obtain revised shock temperatures for Fe. New results match Brown and McQueen’s (1) calculations of the temperatures of 5000 and 5800K at the 200 and 243 GPa transitions in Fe. New sound speed measurements along the Hugoniot of γ-Fe, centered at 1573K, demonstrate that this phase melts at ∼70 GPa and ∼2800 K and the γ phase does not occur above ∼93 GPa. At higher pressures, perhaps over the entire pressure range of the Earth’s molten outer core (132 to 330 GPa), the β (dhcp) phase, and not the ε phase, appears to be the solidus phase of pure Fe.