Effect of Ni addition on the glass-forming ability and soft-magnetic properties of FeNiBPNb metallic glasses

The effect of Ni addition on the glass-forming ability (GFA) and soft-magnetic properties of an (Fe_1-xNi_x)_75.5B_14.5P₇Nb₃ (x=0-0.6) alloy system were investigated. We found that the addition of Ni was effective in allowing the alloy to approach a eutectic point as well as increasing the thermal stability of the supercooled liquid. By increasing the amount of Ni, the supercooled liquid region (ΔT_x), the reduced glass transition temperature T_rg (T_g/T_l) and the γ parameter [T_x/(T_g+T_l)] increased from 49 to 75 K, 0.540 to 0.594 and 0.373 to 0.405, respectively. As a result, novel (Fe_1-xNi_x)_75.5B_14.5P₇Nb₃ bulk metallic glass (BMG) rods with a maximum diameter of 1 mm were synthesized with a composition of x=0.5 and x=0.6 by copper mold casting. These metallic glasses have a moderate saturation magnetization of 0.37-1.20 T with good soft-magnetic properties, i. e. a low coercivity of 1.4-3.3 A/m and a high effective permeability of 13100-20900 at 1 kHz. The simultaneous achievement of a high GFA and good soft-magnetic properties for the FeNi-based alloy system is promising for the future development of BMGs.