Abstract: The process of mechannical alloying of elemental powder mixtures of Fe_xSi_1-x (X=0.30~0.75)is studied with a high energy planetary ball milling.After the structure analasis of powders at different milling time,it showed that nanocrystal αFe(Si)Solid solution(bcc)was formed during the milling of Fe₇₅si₂₅ powders,the lattice spacing and grain size of αFe(Si)decreased with increase of milling time.The milling products of Fe₅₀si₅₀ and Fe₃₀si₇₀ were FeSi compounds and three phases mixture α+FeSi+βFeSi₂,respectively.There was no amorphous product in the studying composition range and a thermodynamics analysis was perfermed.