Tunable and attractive magnetic properties of FeBPSiCu alloys

Highlights: • FeBPSiCu amorphous alloys are synthesized through adjustment of Fe/Cu ratio. • Cu addition triggers the obvious thermodynamic changes in alloys. • Attractive and tunable magnetic softness for alloys in different states are obtained. • Magnetic softness is strongly related to the magnetic domain structures. -- Abstract: Novel Fe_76-xB₁₀P₅Si₉Cu_x (x = 0, 0.5, 1 and 1.5 at.%) amorphous alloys with low Fe content were successfully synthesized with aim of investigating the crystallization behaviors and magnetic properties. Thermodynamic behavior revealed that Cu substitution triggered the transition of primary precipitation phase from Fe₂₃B₆ to α-Fe, which favored the high saturation magnetic flux density (B_s) of alloys after annealing. Through adjustment of Fe/Cu ratio, the Fe₇₅B₁₀P₅Si₉Cu₁ alloy exhibited the attractive and tunable magnetic properties, i.e. the high effective permeability (μ_e) of 25000 and low coercivity (H_c) of 1.3 A/m in amorphous state as well as the high B_s of 1.62 T and μ_e of 18000 in crystallization state. The high B_s could be attributed to the uniform refined composite microstructure, whereas the excellent magnetic softness characterized by magnetic domain patterns was determined by magnetic anisotropy induced via different atomic structures. Such tunable performance can promise alloy a potential soft-magnetic material to meet the requirement of most electric devices.