The effect of Dy2O3/MoS2 co-doping on magnetic performance and microstructure in Nd-Fe-B sintered magnets

•Microstructure optimization was achieved in the Dy2O3/MoS2 co-doped Nd-Fe-B magnets.•Obvious grain refinement of 1.3 μm was observed in the co-doped magnets.•A coercivity enhancement of 9.4% was obtained with a slight decrease of remanence.•The mechanism of the coercivity enhancement was outlined. In this study, the relationship between Dy2O3 and MoS2 on magnetic performance and microstructure in Nd-Fe-B sintered magnets was investigated. Compared with the Dy2O3 doped magnets, the coercivity of the Dy2O3/MoS2 co-doped magnets increased with the increasing of MoS2 content. A comprehensive magnetic performance was achieved in the 2 wt% Dy2O3/0.5 wt% MoS2 co-doped magnets. The coercivity increased from 1563.2 kA/m to 1710 kA/m while there was no obvious decrease in the remanence and maximum energy product. Furthermore, the average grain size decreased from 8 μm to 6.7 μm. In the co-doped magnets, the distribution of Dy element was relatively uniform because Dy atoms were found to avoid the Nd2O2S phase. Besides, the Mo atoms were likely diffused into the Nd2Fe14B phase instead of the Nd-rich phase.