In-situ synthesis of Mg₂Si intermetallics via powder metallurgy process

The solid-state synthesis of Mg₂Si intermetallic compounds has been evaluated in the present paper. The elemental magnesium and silicon powder mixture was employed as starting raw materials. In particular, the influence of the silicon particle by the repeated plastic working (RPW) on the in-situ formation of Mg₂Si is discussed, based on the thermal and structural analysis results by DSC thermal analysis and XRD, respectively. Refined Si particles embedded uniformly in the magnesium matrix via RPW, can drive progressing Mg₂Si synthesis at extremely low temperature; for example, the ignition temperature, Ts = 773 K, to commence the solid-state synthesis of raw powder mixture, was reduced to about 400-430 K. Further plastic working on the mixture causes in-situ formation of Mg₂Si intermetallic compounds with a crystallite size of 30-80 nm. However, the ignition temperature to synthesize Mg₂Si shifts to a higher temperature again. Regarding to the thermal stability of Mg₂Si compounds, the particle size of in-situ synthesized Mg₂Si compounds after annealing at 573 K for 900 s is about 30-100 nm, that is, the remarkable coarsening does not occur during annealing.