Optimization of soft magnetic properties of Fe–Si–B–Cu–C alloys by modulation of Fe/B content and annealing process

For Fe-based amorphous/nanocrystalline alloys, how to meet the high Fe content with strong amorphous formation capability has become a serious challenge. In this paper, the purpose of higher saturation magnetic induction strength is achieved by changing the B content. The effects of Fe content, different annealing processes on the phase structure of Fe_80+xSi₂B_17−xCu_0.5C_0.5 (x = 0, 1, 2, 3, 4) amorphous and nanocrystalline alloys have been systematically investigated by means of XRD, DSC and VSM methods, thermal stability and soft magnetic properties. The results show that the alloys still have the ability to form a single amorphous phase when Fe content reaches 83%. In terms of the thermal stability of the alloy, the increase of Fe content facilitates the obtaining of a larger crystallization temperature interval, which is beneficial to the heat treatment process and the preparation of amorphous/nanocrystalline soft magnetic materials. Comparison of the one-step annealing and two-step annealing processes reveals that the two-step annealing process results in smaller average grain size and smaller coercivity. The heat treatment of the two-step annealing process for different time reveals that holding at 335 °C for 10 min and then increasing to 410 °C for 10 min could modulate the excellent soft magnetic properties with a saturation magnetization (M_s) of 205.7 emu/g and coercivity of 14.9 A/m.