Improving soft magnetic properties in FINEMET-like alloys with Ga addition

The effect of partial substitution of Si by Ga on the microstructure and soft magnetic properties of FINEMET-like Fe_73.5Si_13.5−xNb₃B₉Cu₁Ga_x (x = 0, 3, 6, 9, 12 at.%) alloys has been investigated. It was found that the primary crystallization of ribbons was gradually changed from α-Fe (Si) into α-Fe (Ga, Si) phase with the increase of Ga content. Besides, the Fe-Ga clusters were detected in the amorphous ribbon with x = 6, which could provide nucleation sites for the α-Fe (Ga, Si) phase. In such case, the crystallization temperature of the ribbons with Ga addition was lower than that of ribbon without Ga addition. For the ribbon with x = 6, the precipitation of Ga element was priority to that of Si, which leads to the 'increase-decrease' tendency for the changes of lattice parameter with the increase of annealing temperature. Meanwhile, compared to the α-Fe (Si) phase with enrichment of Si for x = 0 ribbon, the α-Fe (Ga, Si) phase with high Ga and low Si concentration for the x = 6 ribbon was obtained, together with fine grain size (11 nm) of α-Fe (Ga, Si) phase, resulting to the same low coercivity (0.24 A/m), higher saturation magnetization (1.37 T) and maximum permeability after annealed at 455 °C for 1 min.