Systematics of transition-metal melting

We report high-pressure measurements for the melting curve of Ti, V, Cr, Mo, Ta, W, Fe, Co, and Ni. Measurements were made in a laser-heated diamond-anvil-cell to nearly 100 GPa and 4000 K. The bcc metals have surprisingly small melting slopes which approach zero at high pressure. The melting curves of Co, Ni, and Fe are nearly parallel. Several ab-initio calculations for the melting of Fe are incompatible with the present results.