R—Fe—B rare earth sintered magnet and method for producing same
AssigneeHitachi Metals, Ltd.
InventorsKoshi Yoshimura, Hideyuki Morimoto, Tomoori Odaka
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Abstract
In a method for producing an R—Fe—B based rare-earth sintered magnet according to the present invention, first, provided is an R—Fe—B based rare-earth sintered magnet body including, as a main phase, crystal grains of an R2Fe14B type compound that includes a light rare-earth element RL, which is at least one of Nd and Pr, as a major rare-earth element R. Thereafter, the sintered magnet body is heated while a heavy rare-earth element RH, which is at least one element selected from the group consisting of Dy, Ho and Tb, is supplied to the surface of the sintered magnet body, thereby diffusing the heavy rare-earth element RH into the rare-earth sintered magnet body.
Claims11
A method for producing an R—Fe—B based rare-earth sintered magnet, the method comprising the steps of:
- (a) providing an R—Fe—B based rare-earth sintered magnet body including, as a main phase, crystal grains of an R2Fe14B type compound that includes a light rare-earth element RL, which is at least one of Nd and Pr, as a major rare-earth element R;
- (b) arranging a bulk body including a heavy rare-earth element RH, which is at least one element selected from the group consisting of Dy, Ho and Tb, along with the R—Fe—B based rare-earth sintered magnet body in a container;
- and
- (c) heating the container, by a heat treatment furnace in which the container is loaded, so that the bulk body and the R—Fe—B based rare-earth sintered magnet body arranged in the container are heated to a temperature of 700° C. to 1,000° C. to vaporize the heavy rare-earth element RH from the bulk body, thereby diffusing the heavy rare-earth element RH into the R—Fe—B based rare-earth sintered magnet body while supplying the heavy rare-earth element RH from the bulk body to the surface of the R—Fe—B based rare-earth sintered magnet body so that substantially no thin film made of the heavy rare-earth element RH is formed on the R—Fe—B based rare-earth sintered magnet body,
- wherein the step (c) includes arranging the bulk body and the R—Fe—B based rare-earth sintered magnet body out of contact with each other in the container and setting an average gap between the two bodies within the range of 0.1 mm to 300 mm, and
- wherein the step (c) includes setting a difference in temperature between the R—Fe—B based rare-earth sintered magnet body and the bulk body within 20° C.
A method for producing an R—Fe—B based rare-earth sintered magnet, the method comprising the steps of:
- (A) arranging a compact of an R—Fe—B based rare-earth magnet powder, including a light rare-earth element RL (which is at least one of Nd and Pr) as a major rare-earth element R, in a processing chamber such that the compact faces a bulk body including a heavy rare-earth element RH, which is at least one element selected from the group consisting of Dy, Ho and Tb;
- (B) performing a sintering process in the processing chamber, thereby making an R—Fe—B based rare-earth sintered magnet body including crystal grains of an R2Fe14B type compound as a main phase;
- and
- (C) heating the bulk body and the R—Fe—B based rare-earth sintered magnet body in the processing chamber, thereby diffusing the heavy rare-earth element RH into the R—Fe—B based rare-earth sintered magnet body while supplying the heavy rare-earth element RH from the bulk body to the surface of the R—Fe—B based rare-earth sintered magnet body,
- wherein the step (B) includes performing the sintering process for 30 minutes to 600 minutes with a vacuum of 1 Pa to 105 Pa created in the processing chamber and with an atmosphere in the processing chamber maintained at a temperature of 1,000° C. to 1,200° C.,
- wherein the step (C) includes performing the heating process for 10 minutes to 600 minutes with a vacuum of 1×10−5 Pa to 1 Pa created in the processing chamber and with an atmosphere in the processing chamber maintained at a temperature of 800° C. to 950° C., and
- wherein the step (C) includes arranging the bulk body and the R—Fe—B based rare-earth sintered magnet body out of contact with each other in the processing chamber and setting an average gap between the two bodies within the range of 0.1 mm to 300 mm.
Dependencies are inferred from the claim text.