Effects on Glass Forming Ability, Microstructure, Crystallization Behaviors, and Magnetic Properties of Si Substituting for P in Fe-Rich Fe₈₆B_13−xSi_xP₁Cu_0.6Hf_0.4 Alloys

Abstract

In the paper, we have studied the effects on glass forming ability (GFA), microstructure, crystallization behaviors, and saturation magnetization (M_s) of Si substitution for P in Fe-rich Fe₈₆B₁₂Si_xP_1−xCu_0.4Hf_0.6 alloys. The amorphous structure is identified by X-ray diffraction first, and the patterns with Si addition less than x = 0.75 only show one halo scattering peak at 2θ = 45°; further, the ribbons with entirely amorphous structure have been fabricated successfully and the alloys have a good GFA. Then, by differential scanning calorimetry testing, the curves show two separated exothermic peaks and the ribbons will go through a two-step crystallization before reaching stable state; further, the first peak is ensured by the crystallization of a-Fe phase while the second peak is ensured by the precipitation of FeB or Fe(BP) compounds. As Si was added, the apparent activation energy of the first crystallization (E_a1) and the second crystallization (E_a2) shows an increased tendency first and then decreases slightly. By comparison, as x = 0, x = 0.25, and x = 0.5, the ribbons easily form Hf₃P₂ compounds during the first crystallization process simultaneously, where the ribbons of x = 0.75 and x = 1.0 are easier to finish the first crystallization for forming the uniform a-Fe phase entirely. By vibrating sample magnetometer testing, with the addition of Si, M_s value shows an increased trend and reaches to the maximum about 177.5 emu/g (x = 1.0), and which shows an increased trend in the subsequent annealing process and reaches to the maximum 206.3 emu/g (x = 0), 212.3 emu/g (x = 0.25), 214.2 emu/g (x = 0.5), 214.9 emu/g (x = 0.75), and 208.3 emu/g (x = 1.0) as the annealing temperature higher than T_p1 but less than T_x2.