Structure and magnetic properties of Si-rich FeAlSiBNbCu alloys

Abstract Structure and magnetic properties of as-quenched Fe 73.5 − x Al x Si 17.5 B 5 Cu 1 Nb 3 ( 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 H c , saturation magnetic induction B s , initial permeability μ i , maximum permeability μ max as well as the temperature dependence of initial permeability ( μ i –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 Fe 3 (Al,Si) crystalline phase embedded in the residual amorphous matrix, and the Fe 72.7 Al 0.8 Si 17.5 B 5 Cu 1 Nb 3 alloy exhibited excellent room-temperature soft magnetic properties with a very low H c of about 1 A/m, a high B s of 1.13 T, a high μ i of 35,000 and a high μ max of 128,000 respectively. After annealing at 650 °C, Fe 72.7 Al 0.8 Si 17.5 B 5 Cu 1 Nb 3 alloy exhibited excellent high temperature soft magnetic properties, the μ i above 2800 at 10 kHz can keep up to 500 °C.