Improvement of Magnetic Properties of SmCo5/α-Fe Nanocomposite Magnets by Magnetic Field Annealing

In this paper, magnetic field heat treatment was carried out for the SmCoSUB5/SUB/α-Fe amorphous powders prepared by high-energy ball milling. The effects of annealing temperature and magnetic field on the crystallization, microstructure, and magnetic properties of the SmCoSUB5/SUB/α-Fe nanocomposite permanent magnets were studied. The results show that the magnetic field can benefit the crystallization of SmCoSUB5/SUB phase and the degree of crystallinity of SmCoSUB5/SUB/α-Fe alloy. Thus, the remanence and coercivity of the SmCoSUB5/SUB/α-Fe magnets annealed with magnetic field are significant higher than those of the samples annealed without magnetic field. With the increase of annealing temperature in magnetic field heat treatment, the Sm(Co, Fe)5 phase and FeCo phase are gradually crystallized and grew up, while a small amount of Sm₂CoSUB17/SUB phase appears. The best magnetic properties are MSUBr/SUB = 73.29 emu/g, MSUBr/SUB/MSUBs/SUB = 0.59, and HSUBci/SUB = 6.20 kOe, when the annealing temperature is 700 ℃.