Effects of alignment on the magnetic and mechanical properties of sintered Nd-Fe-B magnets

Sintered Nd-Fe-B magnets with various degrees of grain alignment are prepared by the conventional powder metallurgy technique. The magnetic properties, bending strength and fracture morphologies of sintered magnets with different alignment degrees are investigated. The results show that the remanence B_r and maximum energy product (BH)_max increase, while intrinsic coercivity H_cj decreases gradually with increasing the alignment degree. Moreover, the bending strengths measured by applying force parallel (σ_bb∥) and perpendicular (σ _bb⊥) to the alignment magnetic field H_appl present opposite variation tendency, and σ_bb∥ is larger than σ_bb⊥, suggesting the more significant anisotropy of mechanical properties with increasing the degree of grain alignment. Furthermore, the related mechanisms are systematically analyzed.