Identifying the optimal amorphous precursor alloy system for dual-phase nanostructure formation according to the impurity tolerance and crystallization mechanism

The amorphous precursor alloys for nanostructure with high B_s always exhibit a low impurity tolerance, inhibiting mass production. Here, we comparatively studied the FeBSiCu, FeBPSiCu and FePSiCu alloy systems in Fe₈₃B_12-xP_xSi₄Cu₁ (x = 0–12) alloys made with industrial raw materials. Fully amorphous ribbons were readily prepared in the Fe₈₃B₁₂Si₄Cu₁ and Fe₈₃P₁₂Si₄Cu₁ alloys. It is difficult to avoid the surface crystallization induced by the impurities in Fe₈₃B_12-xP_xSi₄Cu₁ (x = 2–8) amorphous alloys with a relatively high amorphous formability. The Fe₈₃B₁₂Si₄Cu₁ alloy exhibits a large crystallization temperature interval (ΔT) which can be further widened by P micro-alloying. The macro-substitution of B by P will lead to a significant decrease of ΔT. The ΔT of the novel Fe₈₃P₁₂Si₄Cu₁ alloy can be effectively widened by increasing the Fe content and microalloying of B, exhibiting a good potential for the combination of superior ΔT, AFA and impurity tolerance. The low impurity tolerance in the Fe₈₃B_12-xP_xSi₄Cu₁ alloys is ascribed to the significant difference in the metallurgical properties of the Fe–B and Fe–P alloys, needing new impurity purification processes. These results will bring a new perspective to develop high B_s precursor alloys and experimental references for critical industrialization.