Patent ID: 11967455
Assignee: YUAN DONG
Field: Materials, metallurgy (Chemistry)
Classification: CPC B  H  C | IPC B  H

Claim 0:
1. A method for preparing a rare-earth permanent magnet by hot press molding, comprising steps of:
1) smelting an RFeB alloy, where R is any one of Nd, Pr, Dy, Tb, Ce, La, Gd, Ho and Y, or any combination of two or more of Nd, Pr, Dy, Tb, Ce, La, Gd, Ho and Y, and the content of the rare-earth R in the RFeB alloy is 27.5% to 30.5% by mass; the RFeB alloy further contains 0.2% to 2% by mass of a metal composition; the metal composition is any one of Al, Cu, Ga, Zr and Nb, or any combination of two or more of Al, Cu, Ga, Zr and Nb in any ratio; and 1% to 10% Fe is replaced with Co;
2) performing hydrogen decrepitation (HD) treatment on the RFeB alloy, and permeating an RTM alloy during the HD treatment, where RT is any one of Nd, Pr, Dy, Tb, Gd, Ho, Y and Sc, or any combination of two or more of Nd, Pr, Dy, Tb, Gd, Ho, Y and Sc in any ratio, and M is any one of Cu, Al and Ga, or any combination of two or more of Cu, Al and Ga in any ratio;
3) performing jet pulverization on the product obtained in the step 2);
4) molding under a magnetic field at room temperature to obtain a green body;
5) preheating the green body in vacuum for 1 h to 10 h at 650° C. to 950° C. and at a vacuum degree of 10−1 to 10−4 Pa;
6) performing hot pressing on the green body comprising: immediately loading the green body into a mold cavity of a hot pressing mold having a temperature close to a preheating temperature at an end of preheating, applying a pressure of 25 to 120 Mpa, maintaining the pressure for 0.3 min to 10 min, hot pressing the green body in an inert gas having an oxygen content less than 200 PPM, naturally or forcedly cooling to the room temperature; and
7) aging to obtain the magnet.