Tailoring the microstructure and soft magnetic properties of (Fe0.83B0.11Si0.02P0.03C0.01)99.5Cu0.5 nanocrystalline alloy based on the rapid annealing

Abstract

In this work, the effects of annealing temperatures and time on the microstructure and soft magnetic properties of (Fe0.83B0.11Si0.02P0.03C0.01)99.5Cu0.5 nanocrystalline alloy were investigated using a new rapid annealing process. The results show that at each annealing temperature, there exists an annealing time for optimum soft magnetic properties. The annealing temperature and time were further optimized, and excellent properties with high saturation magnetic induction Bs of 1.79 T and low coercivity Hc of 2.7 A/m were obtained by annealing at 431 °C for 150 s. A microstructure consisting of uniform and fine α-Fe(Si) grains with high number density and high crystallization volume fraction was found to be the key to ensure high Bs and low Hc. However, with increasing annealing time, it was found that α-Fe(Si) grains existed aggregation phenomenon (in the form of high-angle grain boundaries), with the simultaneous precipitation of Fe-B compound precipitated in the residual amorphous matrix. This not only causes the uneven distribution of nanocrystals, but also destroys the competitive effect between nanocrystals and the stability of the structure, thus deteriorating the soft magnetic properties.