Hitachi Metals, Ltd.

Rintaro Ishii

Futoshi Kuniyoshi

Teppei Satoh

Ryouichi Yamagata

Takeshi Nishiuchi

Hiroyuki Tomizawa

Tsunehiro Kawata

Noriyuki Nozawa

Takayuki Kanda

To provide an R-T-B based sintered magnet including R: 27.5 to 34.0% by mass, RH: 2 to 10% by mass, B: 0.89 to 0.95% by mass, Ti: 0.1 to 0.2% by mass, Ga: 0.3 to 0.7% by mass, Cu: 0.07 to 0.50% by mass, Al: 0.05 to 0.50% by mass, M (M is Nb and/or Zr): 0 to 0.3% by mass, balance T, and inevitable impurities, the following inequality expressions (1), (2), and (3) being satisfied:[T]&#x2212;72.3([B]&#x2212;0.45[Ti])&#x3e;0&#x2003;&#x2003;(1)([T]&#x2212;72.3([B]&#x2212;0.45[Ti]))/55.85&#x3c;13[Ga]/69.72&#x2003;&#x2003;(2)[Ga]&#x2265;[Cu]&#x2003;&#x2003;(3).

R-T-B-based sintered magnet and method for producing same

To provide an R-T-B based sintered magnet having high Band high Hwhile suppressing the content of Dy. Disclosed is an R-T-B based sintered magnet represented by the formula: uRwBxGayCuzAlqM(balance)T, where R is composed of light rare-earth element(s) RL and heavy rare-earth element(s) RH, RL is Nd and/or Pr, RH is Dy and/or Tb, T is Fe, and 10% by mass or less of Fe is capable of being replaced with Co, M is Nb and/or Zr, inevitable impurities being included, and u, w, x, y, z and q are expressed in terms of % by mass; RH accounts for 5% by mass or less of the R-T-B based sintered magnet, 0.4&#x2264;x&#x2264;1.0, 0.07&#x2264;y&#x2264;1.0, 0.05&#x2264;z&#x2264;0.5, 0&#x2264;q&#x2264;0.1, and 0.100&#x2264;y/(x+y)&#x2264;0.340; v=u&#x2212;(6&#x3b1;+10&#x3b2;+8&#x3b3;), where the amount of oxygen (% by mass) is &#x3b1;, the amount of nitrogen (% by mass) is &#x3b2;, and the amount of carbon (% by mass) is &#x3b3;; and v and w satisfy the following inequality expressions: v&#x2264;32.0, 0.84&#x2264;w&#x2264;0.93, and &#x2212;12.5w+38.75&#x2264;v&#x2264;&#x2212;62.5w+86.125.

R-T-B based sintered magnet

Disclosed is a method for producing a magnet, including a step of preparing a magnet represented by the formula: uRwBxGayCuzAlqM(balance)T, where RH is 5% or less, 0.20&#x2264;x&#x2264;0.70, 0.07&#x2264;y&#x2264;0.2, 0.05&#x2264;z&#x2264;0.5, 0&#x2264;q&#x2264;0.1; when 0.40&#x2264;x&#x2264;0.70, v and w satisfy the following inequality expressions: 50w&#x2212;18.5&#x2264;v&#x2264;50w&#x2212;14, and &#x2212;12.5w+38.75&#x2264;v&#x2264;&#x2212;62.5w+86.125; and, when 0.20&#x2264;x&#x2264;0.40, v and w satisfy the following inequality expressions: 50w&#x2212;18.5&#x2264;v&#x2264;50w&#x2212;15.5 and &#x2212;12.5w+39.125&#x2264;v&#x2264;&#x2212;62.5w+86.125, and x satisfy the following inequality expression: &#x2212;(62.5w+v &#x2212;81.625)/15+0.5&#x2264;x&#x2264;&#x2212;(62.5w+v&#x2212;81.625)/15+0.8; a high-temperature heat treatment step of heating the magnet to a temperature of 730&#xb0; C. or higher and 1,020&#xb0; C. or lower, and then cooling to 300&#xb0; C. at a cooling rate of 20&#xb0; C./min; and a low-temperature heat treatment step of heating the magnet to a temperature of 440&#xb0; C. or higher and 550&#xb0; C. or lower.

Method for producing R-T-B based sintered magnet

A method for manufacturing an R-T-B based sintered magnet includes: 1) a step of preparing an R-T-B based sintered magnet material by sintering a molded body, the sintered magnet material having a particular composition and satisfying inequality expressions (1) and (2); 2) a high-temperature heat treatment step of heating the sintered magnet material to a heating temperature of 730&#xb0; C. to 1,020&#xb0; C. and then cooling the sintered magnet material to 300&#xb0; C. at a cooling rate of 5&#xb0; C./min or more; and 3) a low-temperature heat treatment step of heating the sintered magnet material after the high-temperature heat treatment step to 440&#xb0; C. to 550&#xb0; C.:[T]&#x2212;72.3[B]&#x3e;0&#x2003;&#x2003;(1)([T]&#x2212;72.3[B])/55.85&#x3c;13[Ga]/69.72&#x2003;&#x2003;(2)where [T] is a T content in percent by mass, [B] is a B content in percent by mass, and [Ga] is a Ga content in percent by mass.

Method for manufacturing R-T-B based sintered magnet

To provide an R-T-B based sintered magnet having high Band high Hwhile suppressing the content of Dy, and a method for producing the same. Disclosed is an R-T-B based sintered magnet represented by the formula: uRwBxGayCuzAlqMT, where 0.20&#x2264;x&#x2264;0.70, 0.07&#x2264;y&#x2264;0.2, 0.05&#x2264;z&#x2264;0.5, 0&#x2264;q&#x2264;0.1; v=u&#x2212;(6&#x3b1;+10&#x3b2;+8&#x3b3;), where the amount of oxygen (% by mass) is &#x3b1;, the amount of nitrogen (% by mass) is &#x3b2;, and the amount of carbon (% by mass) is &#x3b3;; when 0.40&#x2264;x&#x2264;0.70, v and w satisfy the following inequality expressions: 50w&#x2212;18.5&#x2264;v&#x2264;50w&#x2212;14, and &#x2212;12.5w+38.75&#x2264;v&#x2264;&#x2212;62.5w+86.125; and, when 0.20&#x2264;x&#x2264;0.40, v and w satisfy the following inequality expressions: 50w&#x2212;18.5&#x2264;v&#x2264;50w&#x2212;15.5 and &#x2212;12.5w+39.125&#x2264;v&#x2264;&#x2212;62.5w+86.125, and x satisfy the following inequality expression: &#x2212;(62.5w+v&#x2212;81.625)/15+0.5&#x2264;x&#x2264;&#x2212;(62.5w+v&#x2212;81.625)/15+0.8.

R-T-B based sintered magnet and method for producing R-T-B based sintered magnet

A method for manufacturing an R-T-B based sintered magnet includes: 1) a step of preparing an R-T-B based sintered magnet material by sintering a molded body at a temperature of 1,000&#xb0; C. or higher and 1,100&#xb0; C. or lower, and then performing (a) temperature dropping to 500&#xb0; C. at 10&#xb0; C./min or less, or (b) temperature dropping to 500&#xb0; C. at 10&#xb0; C./min or less after performing a first heat treatment of holding at a first heat treatment temperature of 800&#xb0; C. or higher and 950&#xb0; C. or lower, the R-T-B based sintered magnet material satisfying compositional requirements; and 2) a heat treatment step of performing a second heat treatment by heating the R-T-B based sintered magnet material to a second heat treatment temperature of 650&#xb0; C. or higher and 750&#xb0; C. or lower, and then cooling the R-T-B based sintered magnet material to 400&#xb0; C. at 5&#xb0; C./min or more.

A method is provided for producing an R-T-B based alloy powder. The method includes providing an alloy powder containing 27.5 to 36.0 mass % of R, where R is at least one among the rare-earth elements and always includes at least one of Nd and Pr, 0.85 to 1.05 mass % of B, 0.1 to 2.5 mass % of element M (Al, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Pb and/or Bi), and a balance T, where T is Fe or is Fe and Co; and pulverizing the powder by introducing the powder and a pulverization gas in a pulverization chamber. The pulverization includes attrition while circulating the alloy powder with a flow of the pulverization gas in the pulverization chamber. The pulverization gas has a gauge pressure of 0.75 MPa or more, and the residence time is 6 minutes or more.

R-T-B-based alloy powder and method for producing same, and R-T-B-based sintered magnet and method for producing same

A method for producing a sintered R-T-B based magnet includes providing a sintered R-T-B based magnet body, of which the rare-earth-element mole fraction falls within the range of 31 mass % to 37 mass %; providing an RH diffusion source including a heavy rare-earth element RH (which is at least one of Dy and Tb) and 30 mass % to 80 mass % of Fe; loading the sintered magnet body and the RH diffusion source into a processing chamber so that the magnet body and the diffusion source are movable relative to each other and readily brought close to, or in contact with, each other; and performing an RH diffusion process by conducting a heat treatment on the sintered magnet body and the RH diffusion source at a process temperature of 700&#xb0; C. to 1000&#xb0; C. while moving the sintered magnet body and the RH diffusion source either continuously or discontinuously.

Method for producing R-T-B sintered magnet

An R-T-B based sintered magnet according to the present invention has a composition including: 27.3 mass % to 29.5 mass % of R; 0.92 mass % to 1 mass % of B; 0.05 mass % to 0.3 mass % of Cu; 0.02 mass % to 0.5 mass % of M; and T as the balance, and has an oxygen content of 0.02 mass % to 0.2 mass %. The main phase of the sintered magnet is an RTB type compound. The crystal grain size of the main phase is represented by an equivalent circle diameter of 8 &#x3bc;m or less. And crystal grains with equivalent circle diameters of 4 &#x3bc;m or less account for at least 80% of the overall area of the main phase.

R-T-B-type sintered magnet and method for production thereof

A method for producing a sintered R-T-B based magnet includes the steps of: providing R-T-B based alloy powders A and B so that the R-T-B based alloy powder B has a particle size D50 that is smaller by at least 1.0 &#x3bc;m than that of the R-T-B based alloy powder A and that there is a difference &#x394;RH of at least 4 mass % between the higher content of a heavy rare-earth element RH in the R-T-B based alloy powder B and the lower content of the heavy rare-earth element RH in the R-T-B based alloy powder A; mixing these two R-T-B based alloy powders A and B together; compacting the mixed R-T-B based alloy powder to obtain a compact with a predetermined shape; and sintering the compact.

An R-T-Cu&#x2014;Mn&#x2014;B based sintered magnet includes: 12.0 at % to 15.0 at % of R, which is at least one of the rare-earth elements that include Y and of which at least 50 at % is Pr and/or Nd; 5.5 at % to 6.5 at % of B; 0.08 at % to 0.35 at % of Cu; 0.04 at % to less than 0.2 at % of Mn; at most 2 at % (including 0 at %) of M, which is one, two, or more elements that are selected from the group consisting of Al, Ti, V, Cr, Ni, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Au, Pb and Bi; and T as the balance, which is either Fe alone or Fe and Co and of which at most 20 at % is Co if T includes both Fe and Co.

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Mishima-gun, Japan

Rintaro Ishii