Abstract：Fe-Si-Al alloy magnetic powders used in electric vehicle motors were prepared by mechanical alloying method. The phase structure and morphology of the powders were characterized by X ray diffraction and scanning electron microscopy, their stability was studied by differential thermal analysis. The results show that the mixture powders with atom ratio of (FeSi)₇₅Al₂₅ are milled for 10 h, the nano-crystalline α-Fe(Si,Al) solid solution generates, whose crystal structure is body-centered cubic, their particle size is in range of 1 to 20 μm. The crystal grain size reduces to 30 nm after ball milling for 15 h. During the process of mechanical alloying, the typical layered structure on the surface of (FeSi)₇₅Al₂₅ particles becomes clearly, and different elements distribute uniformly. No amorphous phase creates in the process of mechanical alloying.

Keywords: mechanical alloying; Fe-Si-Al alloy powders; microstructure