Abstract: A method for manufacturing an R-T-B based sintered magnet according the present disclosure comprises: a step for preparing a coarse ground powder which is made from an alloy for R-T-B based sintered magnets and which has an average particle size of 10-500 ?m; a step for obtaining a fine powder having an average particle size of 2.0-4.5 ?m, by feeding the coarse ground powder to a jet mill device that has a grinding chamber filled with inert gas and grinding the coarse ground powder; and a step for producing a sintered body of the fine powder, wherein the inert gas has been humidified, and the oxygen content of the R-T-B based sintered magnet is 1000-3500 ppm by mass.

Abstract: A permanent magnet alloy according to the present disclosure contains Mn at a content not lower than 41% by atom and not higher than 53% by atom; Al at a content not lower than 46% by atom and not higher than 53% by atom; and Cu at a content not lower than 0.5% by atom and not higher than 10% by atom. The alloy contains a stable phase, having a tetragonal structure, at a ratio not lower than 50%.

Abstract: A method for evaluating material properties includes an image processing for evaluation step, a material properties prediction step, and an evaluation step. The image processing for evaluation step includes scanning one or more images for evaluation of a material to be evaluated, creating a low-gradation image for evaluation by lowering gradation of the image for evaluation, and creating a virtual image by processing the low-gradation image for evaluation. The material properties prediction step includes extracting features for evaluation from the low-gradation image for evaluation, predicting a first material property of the material to be evaluated from the features for evaluation through a regression model, extracting a virtual-image feature from the virtual image, and predicting a second material property of the material to be evaluated from the virtual-image features through the regression model. The evaluation step is for comparing the first material property with the second material property.

Abstract: An R—Fe—B based porous magnet according to the present invention has an aggregate structure of Nd2Fe14B type crystalline phases with an average grain size of 0.1 ?m to 1 ?m. At least a portion of the magnet is porous and has micropores with a major axis of 1 ?m to 20 ?m.

Abstract: An R—Fe—B based porous magnet according to the present invention has an aggregate structure of Nd2Fe14B type crystalline phases with an average grain size of 0.1 ?m to 1 ?m. At least a portion of the magnet is porous and has micropores with a major axis of 1 ?m to 20 ?m.

Abstract: An R—Fe—B based porous magnet according to the present invention has an aggregate structure of Nd2Fe14B type crystalline phases with an average grain size of 0.1 ?m to 1 ?m. At least a portion of the magnet is porous and has micropores with a major axis of 1 ?m to 20 ?m.

Abstract: An R—Fe—B based rare-earth alloy powder with a mean particle size of less than about 20 ?m is provided and compacted to make a powder compact. Next, the powder compact is subjected to a heat treatment at a temperature of about 550° C. to less than about 1,000° C. within hydrogen gas, thereby producing hydrogenation and disproportionation reactions (HD processes). Then, the powder compact is subjected to another heat treatment at a temperature of about 550° C. to less than about 1,000° C. within either a vacuum or an inert atmosphere, thereby producing desorption and recombination reactions and obtaining a porous material including fine crystal grains, of which the density is about 60% to about 90% of their true density and which have an average crystal grain size of about 0.01 ?m to about 2 ?m (DR processes). Thereafter, the porous material is subjected to yet another heat treatment at a temperature of about 750° C. to less than about 1,000° C.

Abstract: An R—Fe—B based porous magnet according to the present invention has an aggregate structure of Nd2Fe14B type crystalline phases with an average grain size of 0.1 ?m to 1 ?m. At least a portion of the magnet is porous and has micropores with a major axis of 1 ?m to 20 ?m.

Abstract: An R—Fe—B based rare-earth alloy powder with a mean particle size of less than about 20 ?m is provided and compacted to make a powder compact. Next, the powder compact is subjected to a heat treatment at a temperature of about 550° C. to less than about 1,000° C. within hydrogen gas, thereby producing hydrogenation and disproportionation reactions (HD processes). Then, the powder compact is subjected to another heat treatment at a temperature of about 550° C. to less than about 1,000° C. within either a vacuum or an inert atmosphere, thereby producing desorption and recombination reactions and obtaining a porous material including fine crystal grains, of which the density is about 60% to about 90% of their true density and which have an average crystal grain size of about 0.01 ?m to about 2 ?m (DR processes). Thereafter, the porous material is subjected to yet another heat treatment at a temperature of about 750° C. to less than about 1,000° C.