Abstract:Mechanical milling behavior of Mo-Si-Fe powders was investigated using XRD, SEM and TEM techniques. The mixtures of elemental molybdenum (>99%), silicon (>99%) and iron (>98%) powders with a stoichiometry of Mo_5-xFe_xSi₃(x=0.5, 1, 2) were milled in a planetary mill for up to 195h. For all three powder mixtures, high-energy milling of 60h led to formation of the Mo(Fe, Si) supersaturated solid solution (Mo_ss); and to a remarkable expansion of the solubility of Fe, Si in molybdenum. The transformation of Mo_ss to an amorphous phase was identified after longer time milling. In the milling process, the grain size of Mo (Fe, Si) decreased gradually and the internal stress increased linearly. After 40?h milling, the grain size was reduced to about 11nm. SEM analysis of mil l ed powders showed that the particle size increased initially with milling time. After 195h milling, particles exhibited a spherical morphology and the particle size were reduced to about 100nm.

Key words: silicides；mechanical alloying；structure refinement；alloying effect