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

Abstract

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 ( 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 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.

FeSiBP Bulk Metallic Glasses with Unusual Combination of High Magnetization and High Glass-Forming Ability

“…Taking account of the difference in the optimum annealing temperature for H c , 748 K for the glassy alloy and 653 K for the amorphous alloy, we can see that the Fe 76 Si 9 B 10 P 5 glassy alloy exhibits the higher thermal stability of magnetic softness, which should indicate the higher stability of the glassy phase than the amorphous phase. 11,12) Figure 4 shows the compressive stress-strain curve (a), and SEM micrographs revealing the compressive fracture surface (b) and shear bands on the specimen surface (c) of the Fe 76 Si 9 B 10 P 5 BMG with a diameter of 1.5 mm, respectively. It can be seen that the specimen shows an initial elastic deformation behavior with an elastic strain of 1.9%, then begins to yield at about 3.3 GPa, followed by some plastic deformation of 0.7% before fracture.…”

Developments and Applications of Bulk Glassy Alloys in Late Transition Metal Base System

“…We examined in more details the contribution of internal stress to coercivity. It has previously been reported that the coercivity is proportional to the ratio of saturation magnetostriction ( s ) to saturation magnetization 27) and hence the slope is related to the volume and density of internal defects considering mainly of free volumes in the glassy structure. Figure 8 shows good linear relations between H c and the ratio of s to J s for Fe-based glassy and amorphous alloys.…”

FeCoBSiNb bulk metallic glasses with Cu additions

“…The coercivities are very small and also comparable. It is known that the coercivity strongly depends on the structure of the sample [21,22]; so it is possible to say that the M.A. and (M.A.)…”