| 摘要 |
The invention provides an R—Fe—B sintered magnet consisting essentially of 12-17 at % of Nd, Pr and R, 0.1-3 at % of M1, 0.05-0.5 at % of M2, 4.8+2*m to 5.9+2*m at % of B, and the balance of Fe, containing R2(Fe,(Co))14B intermetallic compound as a main phase, and having a core/shell structure that the main phase is covered with grain boundary phases. The sintered magnet exhibits a coercivity of at least 10 kOe despite a low or nil content of Dy, Tb and Ho. |
| 主权项 |
1. An R—Fe—B base sintered magnet of a composition consisting essentially of 12 to 17 at % of R which is at least two of yttrium and rare earth elements and essentially contains Nd and Pr, 0.1 to 3 at % of M1 which is at least one element selected from the group consisting of Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, 0.05 to 0.5 at % of M2 which is at least one element selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W, 4.8+2×m to 5.9+2×m at % of B wherein m stands for atomic concentration of M2, up to 10 at % of Co, up to 0.5 at % of carbon, up to 1.5 at % of oxygen, up to 0.5 at % of nitrogen, and the balance of Fe, containing R2(Fe,(Co))14B intermetallic compound as a main phase, and having a coercivity of at least 10 kOe at room temperature, wherein
the magnet contains a M2 boride phases at grain boundary triple junctions, but not including R1.1Fe4B4 compound phase, has a core/shell structure that the main phase is covered with grain boundary phases comprising an amorphous and/or sub-10 nm nanocrystalline R—Fe(Co)-M1 phase consisting essentially of 25 to 35 at % of R, 2 to 8 at % of M1, up to 8 at % of Co, and the balance of Fe, or the R—Fe(Co)-M1 phase and a crystalline or a sub-10 nm nano-crystalline and amorphous R-M1 phase having at least 50 at % of R, wherein a surface area coverage of the R—Fe(Co)-M1 phase on the main phase is at least 50%, and the width of the intergranular grain boundary phase is at least 10 nm and at least 50 nm on the average. |
