Magnesium silicide (Mg 2 Si) is a promising intermetallic compound for applications such as light-weight composite materials and thermoelectricenergy conversion.It is difficult, however, to synthesize high-quality Mg 2 Si on a large scale. Self-propagating high-temperature synthesis (SHS) is an attractive pathway, but it is difficult to ignite the low-exothermic Mg/Si mixtureand achieve a self-sustained propagation of the combustion wave. In the present paper, mechanical activation was used to facilitate the ignition. Magnesium and silicon powders were mixed and then milled in a planetary ball mill in an argon environment. The mixtures were compacted into pellets and ignited at the top in a reaction chamber filled with argon. Depending on the pellet dimensions and diameter-to-height ratio, two modes of combustion synthesis, viz.,thermal explosion and SHS, were observed. In both modes, Mg 2 Si product was obtained. Thermocouple measurements have revealed that the exothermic reaction stages include two self-heating events separated by a long period of relatively slow interaction. To clarify the reaction mechanisms, differential scanning calorimetry was used, which also revealed two peaks of exothermic reaction in the milled Mg/Si mixture. The first peak is explained by the effect of mechanical activation. Explosive-based shockwave consolidation was used to increase the product density. Thermophysical properties of the obtained material were determined using a laser flash apparatus.
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