Microstructure and annealing effects of NdFeB sintered magnets with Pr-Cu boundary addition

•Pr-Cu boundary addition was beneficial to the Hcj enhancement of NdFeB magnets.•4.3 and 6.2 kOe Hcj enhancements were obtained in 5 and 10 wt% Pr-Cu samples.•The Hcj enhancements for Pr-Cu samples were mainly related to the 480 °C annealing.•The micromagnetic parameter α increased from 0.491 to 0.656 after optimal annealing treatment.