Relation between microstructure and magnetic properties of shock wave-compressed Nd–Fe–B magnets

The relationship between the microstructure and magnetic properties of Nd–Fe–B sintered magnet compressed by shock wave with 6.26 GPa ≤ p ≤ 7.16 GPa was investigated. It reveals that Nd–Fe–B magnets show a demagnetization behavior after compressed by shock wave. The intergranular fracture is the main occurring phenomenon in the shock wave-compressed magnets. The coercivity of the shock wave-compressed Nd–Fe–B magnets could be recovered after repeating the annealing process. It suggests that only the morphology change just like the intergranular fracture occurs, and there is no structural change in the grain boundary phase in the shock wave-compressed magnet. Matrix phase grain interconnection, microcracks and pores, and alterant orientation relationship between matrix phase and grain boundaries phase are considered as induced factors of demagnetization.