Abstract: A large sintered R—Fe—B magnet, a preparation method and use thereof are provided. The sintered R—Fe—B magnet has a thickness not less than 10 mm in an orientation direction. Any cross section along the orientation direction is marked as a diffusion cross-section area, and a side of the diffusion cross-section area close to the outer surface of the sintered R—Fe—B magnet is marked as the surface of the diffusion cross-section area. The difference between the coercivity of the surface of the diffusion cross-section area and the coercivity at 5 mm away from the surface of the diffusion cross-section area is ?H, and ?H is ?50 kA/m.

Abstract: An R-T-B based permanent magnet material, a preparation method therefor and use thereof are provided. The M compound is adhered to or coats the R-T-B based alloy powders to form a uniform coating layer on the surface of the neodymium-iron-boron powders, so that the rounding transformation of the R-T-B based alloy powders can be achieved, and further the wettability of the R-T-B based alloy powders is improved under the condition of significantly reducing the amount of heavy rare earth metals in the substrate. In addition, the grain boundary phases of M-R and/or M-T-R are present in the grain boundary of the R-T-B based permanent magnet material, the physicochemical properties of the grain boundary phases can be significantly improved, the distribution of the grain boundary phases is improved, and the grain boundary is strengthened.

Abstract: A method for preparing an R—Fe—B based sintered magnet. The method includes: 1) preparing a R1—Fe—B-M alloy, pulverizing the R1—Fe—B-M alloy to yield a R1—Fe—B-M alloy powder, adding a heavy rare earth powder of R2 or R2X and subsequently adding a lubricant to the R1—Fe—B-M alloy powder and uniformly stirring to form a mixture, where R1 being Nd, Pr, Tb, Dy, La, Gd, Ho, or a mixture thereof; M being Ti, V, Cr, Mn, Co, Ga, Cu, Si, Al, Zr, Nb, W, Mo, or a mixture thereof; R2 being at least one from Tb, Dy, and Ho; X being at least one from O, F, and Cl; 2) pressing the mixture obtained in step 1) to form a compact, and sintering the compact in a pressure sintering device in vacuum or in an inactive gas atmosphere to obtain a magnet; and 3) aging the magnet obtained in step 2).

Abstract: A method for preparing an R—Fe—B based sintered magnet. The method includes: 1) preparing a R1—Fe—B-M alloy, pulverizing the R1—Fe—B-M alloy to yield a R1—Fe—B-M alloy powder, adding a heavy rare earth powder of R2 or R2X and subsequently adding a lubricant to the R1—Fe—B-M alloy powder and uniformly stirring to form a mixture, where R1 being Nd, Pr, Tb, Dy, La, Gd, Ho, or a mixture thereof; M being Ti, V, Cr, Mn, Co, Ga, Cu, Si, Al, Zr, Nb, W, Mo, or a mixture thereof; R2 being at least one from Tb, Dy, and Ho; X being at least one from O, F, and Cl; 2) pressing the mixture obtained in step 1) to form a compact, and sintering the compact in a pressure sintering device in vacuum or in an inactive gas atmosphere to obtain a magnet; and 3) aging the magnet obtained in step 2).

Abstract: An R—Fe—B based magnet having gradient electric resistance and a method for producing the same are provided. The magnet includes an exterior layer (G) and a main body layer (H). The exterior layer (G) is connected with the main body layer (H) via a sintered layer (I). The oxygen content in the exterior layer (G) is higher than the oxygen content in the main body layer (H), so the electrical resistivity of the exterior layer (G) is not lower than the electrical resistivity of the main body layer (H). The R—Fe—B based magnet having gradient electric resistance is capable of maintaining high resistance and excellent magnetic performance simultaneously.