Synthesis of WSi2 powder by mechanical alloying

Abstract

The mechanical alloying (MA) is a non-equilibrium powder processing technology and has been applied to many systems, including amorphous alloys, extended solid solutions, metastable crystalline phase and nanocrystalline materials. In this study, the microstructural evolution and phase transformation of W:2Si powder prepared by MA were investigated by XRD and SEM. The results showed that the supersaturated W(Si) solid solution was formed in succession as the intermediate products of MA of W/Si mixture. Then, a mixture of WSi2 microcrystallites and supersaturated W(Si) solid solution was observed. The final product was amorphous WSi2. The total energy of W:2Si powder mixture was raised by MA; thus crystalline WSi2 can be obtained by heat treatment of as milled W(Si) solid solution powder or amorphous WSi2 powder. The formation mechanism of WSi2 during MA was an atomic diffusion process. WSi2 can be synthesised more easily by filling the vial with one-third fill rather than two-third fill.