Improvement in coercivity by high-speed crystallization for PrFeB-Based nanocomposite magnets

We crystallized amorphous Pr₁₂Fe₈₃B₅ flakes by conventional and pulse annealings with various heating rates, and studied the effects of the heating rate on the magnetic and structural properties of the achieved nanocomposite PrFeB/α-Fe magnets. An increase in the heating rate beyond 850 K/min improved the coercivity and the squareness of hysteresis loops. Crystallization by pulse annealing for 1.8 s led to a coercivity of 400 kA/m, a remanence of 1.3 T, and a maximum energy product of 135 kJ/m³, on average. It was also clarified that an increase in the heating rate reduces the grain size and results in a narrow distribution of the grain size. These changes in the nanostructure are consistent with the observed improvement in magnetic properties in terms of micromagnetic simulation of magnetic properties of nanocomposite magnets.