Origin of Low Coercivity of Fe-(Al, Ga)-(P, C, B, Si, Ge) Bulk Glassy Alloys

The magnetic properties of the glassy Fe-(Al, Ga)-(P, C, B, Si, Ge) alloys have been compared with those of the conventional Fe-based amorphous alloys to clarify the feature of the glassy alloys as a soft magnetic material. The glassy Fe-(Al, Ga)-(P, C, B, Si, Ge) alloys exhibit lower saturation magnetization (Js) than that of the conventional Fe-(B, Si, C) amorphous alloys with the same Fe content. The glassy alloys also have larger saturation magnetostriction constant (λs) than that of the conventional Fe-based amorphous alloys with the same Js. However, the glassy alloys tend to show relatively low coercivity (Hc) whereas λs is large. The theoretical analysis on the basis of domain-wall movement suggests that the low Hc originates from the much higher packing density of the glassy alloys than that of the conventional amorphous alloys, which realizes the low density of the quasi-dislocation dipole-type elastic stress sources or the low pinning force due to the elastic stress. The good combination of high glass-forming ability and good soft magnetic properties (especially low Hc) indicates the possibility of future development as new low loss material.