Elemental powder mixtures were ball-milled for 1 to 24 h to produce Fe79Mo10B10Cu1 alloy powders.Particle size,structural and magnetic properties of the mechanically alloyed powders were investigated.Prolonged ball-milling can reduce particle size(about 8 pm)and refine grain size(about 5 nm).Particle distribution and elemental distribution become homogenized as well.Substitutional Mo atoms dissolve into α-Fe lattice,reducing saturation magnetization of the alloy.A single nanocrystalline phase α-(Fe,Mo)forms after ball milling for 15 h,and its lattice parameter increases with the dissolved Mo content.In early stage of the alloying(＜5 h),both residual stress and magnetostrictive coefficient increase.Magnetoelastic anisotropy,therefore,dominates coercivity of the alloy,and contributes to abnormal increase of the coercivity while the grain size becomes smaller.The alloy powder has coercivity of about 2200 A/m even after ball-milled for 24 h.This large coercivity is mainly caused by compressive micro-stain(about 0.52％)and fine boron inclusions(＜1μm).
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