Effect of heating rate on the microstructural and magnetic properties of nanocrystalline Fe81Si4B12P2Cu1 alloys

Abstract

The effect of heating rate on the structural and magnetic properties of the nanocrystalline Fe81Si4B12P2Cu1 alloy has been investigated. Amorphous Fe81Si4B12P2Cu1 alloy was annealed at 753 K for 180 s at different heating rates ranging from 0.05 to 5 K/s in protective argon atmosphere. The structural and magnetic properties of the as-quenched and annealed alloys were studied using X-ray diffractometer (XRD), differential scanning calorimeter (DSC), vibrating sample magnetometer (VSM), and B–H loop tracer, respectively. Amorphous precursor prepared by industry-grade raw materials is obtained. The increase of heating rate is found to be significantly effective in decreasing the grain size of α-Fe(Si) phase, but the grain size increases at higher heating rate. The volume fraction of α-Fe(Si) phase shows a monotonic decrease with the increase of the heating rate. The coercivity Hc markedly decreases with increasing heating rate and exhibits a minimum at the heating rate of 0.5 K/s, while the saturation magnetization, Ms, shows a slight decrease. These results suggest that the effect of heating rate on Hc and Ms is originated from the changes of grain size and the volume fraction of α-Fe(Si) phase.