The formation mechanisms of intermetallic compound particles during the tumbler-ball milling of 2Cu+Al powders and the vibratory ball milling of Mo+2Si powders were investigated by X-ray diffraction and microscopic observations, respectively. Any temperature variations at the mill surface during a tumbler-ball milling of 2Cu+Al powders have not occurred, but the thermodynamically stable intermetallic compound particles, Cu₂Al phases in the vicinity of surface of the equiaxed globular powder particles milled have been formed. The other side, a abrupt rise of temperature, namely, exothermic phenomenon have been occurred in 50h at the mill surface during a vibratory-ball milling with 25.4㎜ balls of Mo+2Si powders, as the results the intermetallic compound particles, i.e, tetragonal MoSi₂ phases have been observed. It was considered that the formation of intermetallic compounds occurred by a combustion synthesis reaction due to the exothermic heat on the basis of the impact energy of ball during the milling.