Effect of heat-treatment on the nanostructural change of W-Cu powder prepared by mechanical alloying

W-30wt.%Cu powder prepared by mechanical alloying (MA) was annealed at various temperatures to investigate the structural change of MA W-Cu powder. From differential scanning calorimeter analysis and transmission electron microscope observation, it was revealed that the recovery of W in MA W-30wt.%Cu powder occurred at 700 degrees C and the W grain started growing also at this temperature. The W grain had grown significantly after annealing at 900 degrees C, and the Cu phase in the MA powder was found to act as Liquid melt near 900 degrees C. The microstructure of the sintered specimen was similar to that of the W-Cu alloy via Liquid phase sintering. This microstructure, even at temperatures below Cu melting, was the new feature observed in the MA W-Cu powder. This suggests that such a microstructure is closely related to the inherent high diffusivity of the nanosized W crystallites as well as the liquid-like behavior of the Cu phase.