Effects of Mn addition on crystallization behavior and soft magnetic properties of Fe–Si–B–P–Cu nanocrystalline alloy

Insufficient glass forming ability and narrow annealing temperature window significantly restrict the development and application of Fe-based nanocrystalline soft magnetic alloys with high Fe content. In this work, (Fe 83.3 Si 4 B 8 P 4 Cu 0.7 ) 100-x Mn x (x = 0–7) alloys were designed and fabricated by melt-spinning, and the influences of Mn on glass forming ability, crystallization behavior and magnetic properties of this series of high Fe containing alloys have been systematically investigated. It is found that the fully amorphous structure can be obtained when Mn content is less than 7 at.%. The effective annealing temperature window could be broadened by Mn addition. It is also demonstrated that α-Fe grains could be refined by Mn doping, leading to the decrease in coercivity and the increase in permeability. After annealing at 500 °C for 6 min, the (Fe 83.3 Si 4 B 8 P 4 Cu 0.7 ) 99 Mn 1 nanocrystalline alloy exhibits excellent comprehensive soft magnetic properties including high saturation magnetization of 1.6 T, low coercivity of 3.75 A/m and high permeability of 12,142. Moreover, a magnetic field annealing under a relatively low magnetic field intensity of 0.02 T would suppress the precipitation of α-Fe grain and relieve residual stress, thus resulting in better soft magnetic properties.