Study on the high coercivity enhancement mechanism of Sm(CoFeCuZr)z sintered magnets doped by Sm71Cu29

The powders with a nominal composition of Sm(Co0.715Fe0.20Cu0.06Zr0.025)(7.86) are doped by Sm71Cu29 powders with different mass percentages to prepare magnets. When the doping amount is 1 wt% and the sintering and solution temperatures are 1215 degree celsius and 1175 degree celsius, we obtain a magnet with the best overall performance: B-r = 11.02 kG, H-cj = 36.46 kOe, (BH)(max) = 27.36 MGOe, S-r = 78.4 %. Comparing element distribution and microstructure of the undoped magnet with those of the 1 wt% doped magnet, it is found that the doped magnet possesses more 1:5 phases with low domain wall energy, the Cu-lean grain boundaries are significantly improved, and the cellular structure is more uniform and complete. By doping a small amount of powder to regulate the redistribution of Cu element, the coercivity of the magnet is greatly improved, increasing by 140 %. Compared with the magnet with the same overall composition, the element distribution of the magnet doped with 1 wt% Sm71Cu29 is more uniform, which also makes the performance of the doped magnet better.