Hitachi Metals, Ltd.

Teppei Satoh

Futoshi Kuniyoshi

Rintaro Ishii

Takeshi Nishiuchi

Ryouichi Yamagata

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.

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Mishima-gun, Japan

Teppei Satoh