Study of the coercivity for Nd-Fe-B-Ga sintered magnets

The Ga-composition dependence of the Curie temperature, the anisotropy field, and the coercivity are studied for Nd-Fe-B-Ga sintered magnets. It is shown that a smaller addition of Ga atoms increases not only the Curie temperature but also the coercivity. A rise in coercivity does not result from the change of anisotropy field for Nd/sub 16/Fe/sub 77/B/sub 7-x/Ga/sub x/ sintered magnets. It is also found that the coercivity for a Nd/sub 16/Fe/sub 77/Ga/sub 2/B/sub 5/ magnet, which has lower B content, is controlled by nucleation whereas for the magnet Nd/sub 13.5/Dy/sub 1.5/Fe/sub 75/Al/sub 2/B/sub 8/ (iH/sub c/=18 kOe), two kinds of coercivity mechanisms (pinning and nucleation) coexist. >