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 (J(s)) 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 (lambda(s)) than that of the conventional Fe-based amorphous alloys with the same J(s). However, the glassy alloys tend to show relatively low coercivity (H-c) whereas lambda(s) is large. The theoretical analysis on the basis of domain-wall movement suggests that the low H-c 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 H-c) indicates the possibility of future development as new low loss material.