In general, the grain size in micromagnetic modeling for hot-deformed magnets is determined by the size of the c-plane and the aspect ratio, which cannot reflect the randomness of the grain shape. In this study, we consider, from a micromagnetic point of view, the effect of circularity as a quantity to characterize the irregular shape of platelet grains of hot-deformed magnets. In the absence of the defect layer, there is very little variation in the coercivity of micromagnetic systems with different circularities, while the coercivity is significantly dependent on the circularity for micromagnetic systems with the defect layer. The simulated results show that the circularity can be regarded as a microstructural index, characterizing the random shape of grains in hot-deformed Nd–Fe–B magnets.
Kim et al. (Sun,) studied this question.