Synthesis of Mg₂Si Powder by Mechanical Alloying and Its Consolidation

Abstract

In this work, bulk Mg₂Si has been processed using the PM route. The Mg₂Si powders were synthesized by the mechanical alloying technique and were characterized microstructurally and thermally. The mechanical alloying was attained at room temperature by the use of a high ball-to-powder ratio of 33:1. An X-ray diffraction technique was used to follow the alloying process. Powders obtained from an Al–Mg₂Si two-phase aluminium ternary alloy by dissolving the aluminium matrix were also obtained as reference intermetallic compounds. Although both kinds of powders exhibited a good compaction behavior, the compact fabricated from the mechanically alloyed powders showed the highest green density. The thermal characterization of the intermetallic by differential scanning calorimetry and thermogravimetry showed a low thermal stability. The intermetallic Mg₂Si exhibited a mass gain due to its oxidation at temperatures above 773 K even under the pressure of 1.33×10⁻³ Pa. This phenomenon limits its processing capability during the sintering step, since the experiment must be conducted at intermediate temperatures below 773 K.