Coercivity improvement for vanadium carbide (VC) doped sintered Nd−Fe−B magnets: Effectively tuning microstructure

Abstract Vanadium carbide (VC) nano‐particles were introduced into sintered Nd−Fe−B magnets for the purpose of grain refinement and coercivity enhancement. The effect of vanadium carbide (VC) addition on the microstructure and magnetic properties evolution of sintered Nd−Fe−B magnets was studied. Based on the characterization results, the additive vanadium carbide (VC) nano‐particles mainly reacted with rare earth (RE)‐rich phase to form ferrovanadium (FeV) phase, which rooted in the grain boundary. The ferrovanadium (FeV) phase inserted influence on the dissolution‐precipitation process and acted as pinning sites and heterogeneous nucleation sites, which was favorable for the grain refinement. As a result, the coercivity of sintered magnets enhanced significantly from 13.62 kOe to 16.15 kOe without obvious decline of remanence when the vanadium carbide (VC) nano‐particles additive amount increased from 0 wt.–% to 0.1 wt.–%. The above findings shed light on the microstructure manipulation to obtain high performance sintered magnets.