Effect of annealing temperature on structure and high-temperature soft magnetic properties of (Fe0.9Co0.1)72.7Al0.8Si13.5Cu1Nb3B8V1 nanocrystalline alloy

Abstract The structure and soft magnetic properties of nanocrystalline (Fe0.9Co0.1)72.7Al0.8Si13.5Cu1Nb3B8V1 alloy annealed at 510−690 °C were investigated by XRD patterns and initial permeability. It was observed that annealing within the ranges of 510−630 °C, only soft magnetic crystalline phase precipitated from the amorphous matrix. With the increase of annealing temperature, the grain size (D) and volume fraction of the crystalline phase (Vcry) both gradually increase from 11.9 nm to 13.7 nm and from 58 % to 89 % respectively. In the meanwhile, the thickness of the amorphous layer (Λ) gradually decreases from 2.37 nm to 0.54 nm. The change of initial permeability with temperature (μi -T curves) showed that the μi declines with increasing temperature. However, the rate of descent is different and the higher annealing temperature (Ta) corresponds to the slower attenuation of μi. The high-temperature μi gradually improves with annealing temperature (Ta) increasing up to 630 °C, and the higher μi of 1500 can be held up to 600 °C. However, the high-temperature μi dramatically deteriorates after annealing at 690 °C due to the precipitating hard magnetic phase from the residual amorphous matrix.