Structure and magnetic properties of Si-rich FeAlSiBNbCu alloys

Structure and magnetic properties of as-quenched Fe73.5 − xAlxSi17.5B5Cu1Nb3 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) alloys annealed at different temperatures were investigated. Structure has been analyzed from XRD patterns. Magnetic properties were mainly studied by the coercivity Hc, saturation magnetic induction Bs, initial permeability μi, maximum permeability μmax as well as the temperature dependence of initial permeability (μi-T curves). The results showed that when annealing at 550 °C for 30 min, the alloy gave rise to an ultrafine structure composed of α-Fe(Al,Si) and Fe3(Al,Si) crystalline phase embedded in the residual amorphous matrix, and the Fe72.7Al0.8Si17.5B5Cu1Nb3 alloy exhibited excellent room-temperature soft magnetic properties with a very low Hc of about 1 A/m, a high Bs of 1.13 T, a high μi of 35,000 and a high μmax of 128,000 respectively. After annealing at 650 °C, Fe72.7Al0.8Si17.5B5Cu1Nb3 alloy exhibited excellent high temperature soft magnetic properties, the μi above 2800 at 10 kHz can keep up to 500 °C.