2017 Volume 58 Issue 5 Pages 825-828
This paper reports improvement of the coercivity of Nd-Fe-B powder by Nd-Cu sputtering. The total rare earth element content of the Nd-Fe-B powder increased by 0.8 mass% after Nd-Cu sputtering, and the sputtered Nd-Cu was observed at the surface of Nd-Fe-B powder by microstructural observation. The coercivity (Hc) of the Nd-Cu-sputtered Nd-Fe-B powder improved after annealing at temperatures above 600℃, and Hc of the sputtered powder reached a maximum value of 1312 kA m−1 after annealing at 900℃. This Hc value was 470 kA m−1 higher than that of Nd-Fe-B powder without sputtering. Isotropic green compacts were prepared from Nd-Fe-B powders with and without Nd-Cu sputtering, and the sputtering also improved Hc in the compacts. The compact prepared from powder with sputtering had Hc of 630 kA m−1 higher than that of the compact prepared from powder without sputtering after annealing at 900℃. Microstructure observation showed that the improvement of Hc was due to an increase in the Nd-rich phase in the compact by Nd-Cu sputtering.