PHASE-TRANSFORMATION IN MO-RU ALLOY INDUCED BY LASER-HEATING AT HIGH-PRESSURES

Phase transformations in the Mo-Ru alloy system were investigated at h igh pressures and high temperatures in a laser-heated diamond anvil ce ll. The room temperature compression of Mo-20 at% Ru alloy to 67 GPa r evealed that the BCC phase is stable to the highest pressure. Laser he ating at high pressures performed without an insulating medium resulte d in the formation of Mo2C phase. However, controlled laser heating to 2200 K at 20 GPa with KCI insulating medium showed that the BCC phase transforms into a mixture of BCC and sigma (a) phases. The present ph ase-stability data are discussed within the context of the rigid-band model and electron transfer under high pressures in transition metal s ystems.