# US 2014/0191833 A1 · Method for producing rare earth magnets, and rare earth magnets > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191833 A1 - Document ID: US20140191833A1 - Status: Published application - Kind: A1 - Application number: 14/240,133 - Filed: 2012-08-22 - Published: 2014-07-10 - Earliest claimed: 2011-08-23 - Assignees: Toyota Jidosha Kabushiki Kaisha - Inventors: Noritsugu Sakuma; Hidefumi Kishimoto - Web page: https://patentgrep.com/patent/US20140191833A1 ## CPC - H01F 1/057: and IIIa elements, e.g. Nd2Fe14B - C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60} - C22C 38/005: {containing rare earths, i.e. Sc, Y, Lanthanides} - C22C 38/10: containing cobalt - H01F 1/0577: {sintered} - H01F 41/0293: {diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets} - B22F 2998/10: Processes characterised by the sequence of their steps - C21D 2201/03: Amorphous or microcrystalline structure - C22C 2202/02: Magnetic - H01F 1/0579: {with exchange spin coupling between hard and soft nanophases, e.g. nanocomposite spring magnets} - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - C22C: ALLOYS (treatment of alloys C21D, C22F) - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER - C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B) ## Abstract A method for producing a nanocrystalline rare earth magnet having a grain and a grain boundary phase includes: quenching a melt of a rare earth magnet composition to form a quenched thin ribbon having a nanocrystalline structure; sintering the quenched thin ribbon to obtain a sintered body; heat treating the sintered body at a temperature which is higher than a lowest temperature in a first temperature range where the grain boundary phase diffuses or flows, and which is lower than a lowest temperature in a second temperature range where the grain becomes coarse; and quenching the heat treated sintered body to 200° C. or less at a cooling speed of 50° C./min or more. ## Claims ### Claim at position 1 -18. (canceled) ### Claim 19 A rare earth magnet that is represented by the following composition formula: RvFewCoxByMz, wherein R is one or more kinds of rare earth elements including Y, M is at least one kind of Ga, Zn, Si, Al, Nb, Zr, Ni, Cu, Cr, Hf, Mo, P, C, Mg, V, Hg, Ag and Au, 13≦v≦20, w=100-v-x-y-z, 0≦x≦30, 4≦y≦20, and O≦z≦3. wherein the rare earth magnet is constituted of either one of the following (i) and (ii): (i) a main phase R2(FeCo)14B, and a grain boundary phase R(FeCo)4B4 and R, and (ii) a main phase R2(FeCo)14B, and a grain boundary phase R2(FeCo)17 and R; and wherein a minimum value of an atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy dispersive X-ray spectrometry is 1.00 or less. ### Claim 20 A rare earth magnet that is represented by the following composition formula: RvFewCoxByMz, wherein R is one or more kinds of rare earth elements including Y, M is at least one kind of Ga, Zn, Si, Al, Nb, Zr, Ni, Cu, Cr, Hf, Mo, P, C, Mg, V, Hg, Ag and Au, 13≦v≦20, w=100-v-x-y-z, 0≦x≦30, 4≦y≦20, and 0≦z≦3, wherein the rare earth magnet is constituted of either one of the following (i) and (ii): (i) a main phase Nd2Fe14B, and a grain boundary phase R(FeCo)4B4 and R, and (ii) a main phase Nd2Fe14B, and a grain boundary phase R2(FeCo)17 and R; and wherein a minimum value of an atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy dispersive X-ray spectrometry is 1.00 or less. ### Claim 21 (depends on 19) The rare earth magnet according to claim 19, wherein the minimum value of the atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy-dispersive X-ray spectrometry is 0.90 or less. ### Claim 22 (depends on 21) The rare earth magnet according to claim 21, wherein the minimum value of the atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy-dispersive X-ray spectrometry is 0.80 or less. ### Claim 23 (depends on 22) The rare earth magnet according to claim 22, wherein the minimum value of the atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy-dispersive X-ray spectrometry is 0.70 or less. ### Claim 24 (depends on 23) The rare earth magnet according to claim 23, wherein the minimum value of an atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy-dispersive X-ray spectrometry is 0.60 or less. ### Claim 25 (depends on 19) The rare earth magnet according to claim 19, wherein a concentration of M is 0.05 to 0.5 atomic percent. ### Claim 26 (depends on 19) The rare earth magnet according to claim 19, wherein the rare earth element is at least one of Y and lanthanides. ### Claim 27 A production method of a nanocrystalline rare earth magnet having a grain and a grain boundary phase comprising: quenching a melt of a rare earth magnet composition to form a quenched thin ribbon having a nanocrystalline structure; sintering the quenched thin ribbon to obtain a sintered body; applying an alignment treatment to the sintered body; after the alignment treatment was applied, heat treating the sintered body at a heat treatment temperature which is higher than a lowest temperature in a first temperature range where the grain boundary phase diffuses or flows, and which is lower than a lowest temperature in a second temperature range where the grain becomes coarse; and quenching the heat treated sintered body to 200° C. or less at a cooling speed of 50° C./min or more. ### Claim 28 (depends on 27) The production method according to claim 27, wherein the heat treatment temperature is a temperature which is higher than a melting temperature or eutectic temperature of the grain boundary phase, and which is in a third temperature range where a grain size after the sintered body is heat treated is 300 nm or less. ### Claim 29 (depends on 27) The production method according to claim 27, wherein the heat treatment temperature is 450 to 700° C. ### Claim 30 (depends on 27) The production method according to claim 27, wherein a holding time while the sintered body is heat treated is in the range of 1 min to 5 hr. ### Claim 31 (depends on 27) The production method according to any one of claim 27, wherein an additive element that decreases the lowest temperature in the first temperature range where the grain boundary phase diffuses or flows is added to the rare earth magnet composition. ### Claim 32 (depends on 31) The production method according to claim 31, wherein the rare earth magnet contains Nd, and the additive element is an element that decreases a melting temperature or eutectic temperature of the grain boundary phase to a temperature which is lower than the melting temperature of Nd simple substance. ### Claim 33 (depends on 31) The production method according to claim 31, wherein the additive element is selected from Al, Cu, Mg, Fe, Co, Ag, Ni, and Zn. ### Claim 34 (depends on 27) The production method according to any one of claim 27, wherein the rare earth magnet composition is represented by the following composition formula: RvFewCoxByMz wherein, R is one or more kinds of rare earth elements including Y, M is at least one kind of Ga, Zn, Si, Al, Nb, Zr, Ni, Cu, Cr, Hf, Mo, P, C, Mg, V, Hg, Ag and Au, 13≦v≦20, w=100-v-x-y-z, 0≦x≦30, 4≦y≦20, and 0≦z≦3, wherein the rare earth magnet is constituted of either one of the following (i) and (ii): (i) a main phase R2(FeCo)14B, and a grain boundary phase R(FeCo)4B4 and R, and (ii) a main phase R2(FeCo)14B, and a grain boundary phase R2(FeCo)17 and R, and wherein a minimum value of an atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy dispersive X-ray spectrometry is 1.00 or less. ### Claim 35 (depends on 27) The production method according to claim 27, wherein the rare earth magnet composition is represented by the following composition formula: RvFewCoxByMz, wherein, R is one or more kinds of rare earth elements including Y, M is at least one kind of Ga, Zn, Si, Al, Nb, Zr, Ni, Cu, Cr, Hf, Mo, P, C, Mg, V, Hg, Ag and Au, 13≦v≦20, w=100-v-x-y-z, 0≦x≦30, 4≦y≦20, and 0≦z≦3, wherein the rare earth magnet is constituted of either one of the following (i) and (ii): (i) a main phase Nd2Fe14B, and a grain boundary phase R(FeCo)4B4 and R, and (ii) a main phase Nd2Fe14B, and a grain boundary phase R2(FeCo)17 and R; and wherein a minimum value of an atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy dispersive X-ray spectrometry is 1.00 or less. ### Claim 36 (depends on 20) The rare earth magnet according to claim 20, wherein the minimum value of an atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy-dispersive X-ray spectrometry is 0.90 or less. ### Claim 37 (depends on 36) The rare earth magnet according to claim 36, wherein the minimum value of an atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy-dispersive X-ray spectrometry is 0.80 or less. ### Claim 38 (depends on 37) The rare earth magnet according to claim 37, wherein the minimum value of an atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy-dispersive X-ray spectrometry is 0.70 or less. ### Claim 39 (depends on 38) The rare earth magnet according to claim 38, wherein the minimum value of an atomic ratio of Fe to Nd in the grain boundary phase when analyzed by energy-dispersive X-ray spectrometry is 0.60 or less. ### Claim 40 (depends on 20) The rare earth magnet according to claim 20, wherein a concentration of M is 0.05 to 0.5 atomic percent. ### Claim 41 (depends on 20) The rare earth magnet according to claim 20, wherein the rare earth element is at least one of Y and lanthanides.