R-T-B based sintered magnet
An R-T-B based sintered magnet according to the present invention comprises: 12 at % to 15 at % of a rare-earth element R; 5.0 at % to 8.0 at % of boron B; 0.02 at % to 0.2 at % of Mn; and a transition metal T as the balance. The rare-earth element R is at least one element selected from the rare-earth elements, including Y (yttrium), and includes 0.2 at % to 8 at % of Pr. And the transition element T includes Fe as its main element.
1. An R-T-B based sintered magnet having a composition comprising:
12 at % to 15 at % of a rare-earth element R;
5.0 at % to 8.0 at % of boron B;
0.02 at % to less than 0.2 at % of Mn; and
a transition metal T as the balance; wherein
the rare-earth element R is at least one element selected from the group of elements consisting of the rare-earth elements and Y and includes at least Nd and Pr, where the content of Pr being 0.2 at % to 8 at % of the sintered magnet; and
the transition metal T includes Fe as its main element.
2. The R-T-B based sintered magnet of claim 1 , wherein the rare-earth element R includes at least one of Tb and Dy in addition to Nd and Pr.
3. The R-T-B based sintered magnet of claim 1 , wherein the magnet includes 20 at % or less of Co as the transition metal T.
4. An R-T-M-B based sintered magnet having a composition comprising:
12 at % to 15 at % of a rare-earth element R;
5.0 at % to 8.0 at % of boron B;
0.02 at % to less than 0.2 at % of Mn;
more than 0 at % to 5.0 at % of an additive element M; and
a transition metal T as the balance; wherein
the rare-earth element R is at least one element selected from the group of elements consisting of the rare-earth elements and Y and includes at least Nd and Pr, where the content of Pr being 0.2 at % to 8 at % of the sintered magnet;
the transition metal T includes Fe as its main element; and
the additive element M is at least one element selected from the group consisting of Al, Ni, Cu, Zn, Ga, Ag, In, Sn, Bi, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W.
5. The R-T-M-B based sintered magnet of claim 4 , wherein the rare-earth element R includes at least one of Tb and Dy in addition to Nd and Pr.
6. The R-T-M-B based sintered magnet of claim 4 , wherein the magnet includes 20 at % or less of Co as the transition metal T.