Formation of nanocrystalline $MoSi_2$ compound subjected to mechanical alloying

Abstract

Molybdenum disilicide has been recognized as an attractive candidate material for high temperature structural applications. In this study, we have used mechanical alloying by a high-energy ball milling process to produce alloy powders of ${\alpha}-MoSi_2$ starting from mixtures of elemental molybdenum and silicon powders at room temperature. The ${\alpha}-MoSi_2$ plus Mo phases have been obtained by ball milling of a $Mo_{33}Si_{67}$ mixture of the pure elements for 100 hours, which was transformed to a single ${\alpha}-MoSi_2$ phase by subsequent heat treatment up to $725\;^{\circ}C$. The grain size of the ${\alpha}-MoSi_2$ powders thus obtained was 19 nm, being approximately four times smaller than that of commercial alloy powders. It was also seen that the ${\alpha}-MoSi_2$ phase once formed begins to transform to the high-temperature ${\beta}-MoSi_2$ phase when the total milling time exceeds 160 hours.

Keywords

• Mechanical alloying (MA);
• Nanocrystalline ${\alpha}-MoSi_2$ compound;
• High-temperature structural material;
• Hall plot;
• Differential scanning calorimetry (DSC)