Effect of milling and annealing parameters on formation of (Mo 0·85 –Cr 0·15 )Si 2 nanocomposite powder

Abstract

Effects of the milling time, annealing temperature and vial rotation speed were investigated on the formation of MoSi₂–CrSi₂ nanocomposite powder. X-ray diffraction was used to characterise the milled and annealed powders. The morphological and microstructural evolutions were studied by scanning electron microscopy and transmission electron microscopy. Results showed that this composite formed after 20 h of milling with mechanically induced self-sustaining reaction mechanism at the cup speed of 640 rev min⁻¹. On the other hand, this composite was partially synthesised after 50 h of milling with the gradual mode at the cup speed of 540 rev min⁻¹. Low temperature polymorph of MoSi₂ and CrSi₂ were obtained after annealing at 1000°C at both speeds. The mean grain size <25 nm was procured for MoSi₂–CrSi₂ composite at both speeds on the basis of peak profile analysis and transmission electron microscopy. This composite maintained its nanocrystalline nature after annealing.