Modulating magnetic properties of high entropy soft FeSiB(P)Cu alloys with excellent GFA via α-Fe(Si) grain preferential growth mechanism

The harmony between glass-forming ability (GFA) and soft magnetic properties (SMPs) of Fe-based amorphous/nanocrystalline alloys has garnered considerable attention. Herein, a prototypical FeSiBCu amorphous alloy system by microalloying P was investigated regarding the GFA, thermal stability, SMPs, and microstructure. It was found that including P not only raised the degree of amorphous disorder but also facilitated the precipitation of alpha-Fe(Si) grains and widened the annealing window. Furthermore, adding P changed the optimal crystallographic orientation of the alpha-Fe(Si) phase and enhanced the growth competition of grains with different orientations, which promoted grain refinement (The average grain size was decreased from 61.36 to 21.24 nm). After optimal annealing processing, the ribbons with 8 at.% P addition displayed a lower coercivity (Hc) of 4.61 A/m. While the 4 at.% P-added ribbons exhibited a higher saturation magnetic flux density (Bs) of 1.75 T. The distinctive mechanism of grain preferential growth in FeSiBPCu alloys provides relevant guidance on the correlation between nanocrystalline structure evolution and the modulation of SMPs.