Relationship among intrinsic magnetic parameters and structure and crucial effect of metastable Fe3B phase in Fe-metalloid amorphous alloys

Abstract

The intrinsic heterogeneity of an amorphous structure originates from composition, and the structure determines the magnetic properties and crystallization models of amorphous magnets. Based on classical Fe–B binary magnetic amorphous alloys, the relationship between the structure and magnetic properties was extensively studied. The stacking structure of Fe–B binary amorphous alloys exhibit discontinuous changes within the range of 74–87 at.% Fe. The structural feature can be expressed as Amor. Fe3B matrix + Fe atoms are transforming into Amor. Fe matrix + B atoms with the increase of Fe content. The solute atoms are uniformly distributed in the amorphous matrix holes, similar to a single-phase solid solution structure. The transition point corresponds to the eutectic crystallization model composition (Fe82B18 to Fe83B17). A high Fe content will amplify magnetic moment sensitivity to temperature. Under a given service temperature, the disturbance effect of magnetic moment self-spinning will offset the beneficial effect of increasing Fe content and induce the saturation magnetization (Ms) value to decrease. Binary amorphous Fe–B alloys obtain the maximum Curie temperature near 75 at.% Fe, which is slightly smaller than that of the corresponding metastable Fe3B phase, i.e., the amorphous short-range order structure maintains the highest similarity to the Fe3B phase. The chemical short-range ordering (SRO) structure of amorphous alloys exhibits heredity to corresponding (meta)stable crystal phases. The unique spatial orientation structure of the metastable Fe3B phase is the structural origin of the amorphous nature. This study can guide the composition design of Fe-metalloid magnetic amorphous alloys. The design of materials with excellent magnetic properties originates from a deep understanding of precise composition control and temperature disturbance mechanism.