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- x Fe x Si 3 ( x =0.5, 1, 2) were milled in a planetary mill for up to 195?h. For all three powder mixtures, high energy milling of 60?h 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 11?nm. SEM analysis of milled powders showed that the particle size increased initially with milling time. After 195?h milling, particles exhibited a spherical morphology and the particle size were reduced to about 100?nm. The mixtures of elemental molybdenum (> 99%), silicon (> 99%) and iron (> 98%) powders with a stoichiometry of Mo 5- x Fe x Si 3 (x = 0.5, 1, 2) were milled in a planetary mill for up to 195? h. For all three powder mixtures, high energy milling of 60? h 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 After 40? H milling, the grain size was reduced to about 11? Nm. SEM analysis of milled powders showed that the particle size increased initially with milling time. After 195? (Fe, Si) decreased gradually and the internal stress increased linearly. h milling, particles exhibited a spherical morphology and the particle size were reduced to a bout 100? nm.