JP4764526B2 - Permanent magnet and manufacturing method thereof, permanent magnet for motor and permanent magnet motor - Google Patents

Description

【表１Ｂ】

【００８４】
表１Ａ及び表１Ｂから分かるとおり、本実施例にかかる永久磁石では保磁力は高すぎず、小さすぎず、また保磁力のばらつきも小さく、リコイル透磁率も小さいことが分かった。また、いずれも焼結密度９８％以上であった。
【００８５】
（比較例）
表２Ａ及び表２Ｂに比較例を示した。
【表２Ａ】

［表２Ｂ］

［００８６］
（比較例１，２，３）
表２Ａに示す組成について、高周波溶解して得た比較例１，２，３のインゴットをブラウンミルで粒子径１〜５μｍに粉砕した後、磁場中成形した。この成形体を真空中で焼結した後、冷却し、再度１１００℃で溶体化し、８５０℃、２時間時効処理後、０．５℃／ｍｉｎの速度で５００℃まで冷却し、時効処理を行なった。磁気特性を評価した結果、表２Ａに示すとおり、いずれも保磁力が高いものが得られた。
【００８７】
（比較例４，５）
純度９９．９％以上のＳｍ２６．０ｗｔ％、純度９９．８％のＣｏ４７．３ｗｔ％、Ｆｅ１２．８ｗｔ％、Ｎｉ５．３ｗｔ％、およびＣｕ８．６ｗｔ％からなる合金を、アルゴン雰囲気で高周波溶解・鋳造した。表２Ａには原子比に換算した合金の組成比を表示する。得られた合金にアルゴン雰囲気中で１１８０℃、４時間インゴツト溶体化処理を施した。溶体化処理後、合金を液体窒素にて冷却速度１２００℃／ｍｉｎ．で急速冷却した。次いで、得られた試料を鉄乳鉢で粗粉砕した後、有機溶剤中でボール・ミルにより平均粒度４μｍの微粉末とした。得られた微粉末を１５ｋＯｅの磁界中でプレスし、圧縮成型体と成した。
【００８８】
この圧縮成型体を２００Ｔｏｒｒのアルゴン雰囲気中で１２１０℃、２時間焼結し、ひき続いて１１９０℃、２時間の焼結後溶体化処理を施した後、１５０℃／ｍｉｎの冷却速度で急速冷却した。さらに８００℃、４時間の時効処理を施し、比較例４とした。また、１１８０℃、４時間のインゴツト溶体化処理を施すことなく、上記比較例４と同様の製造方法により比較例５の永久磁石を得た。
【００８９】
比較例４では、保磁力６．５ｋＯｅが得られる一方で、比較例５では保磁力４．３ｋＯｅが得られた。特に、比較例５では保磁力のばらつきが大きかった。
【００９０】
（比較例６，７）
比較例６の永久磁石を以下の方法で作製した。Ｃｅ_０．５６Ｓｍ_０．４４（Ｃｏ_{０．６９７}Ｃｕ_０．１３Ｆｅ_０．１６Ｚｒ_{０．０１３}）_６．２で与えられる組成の粉末を無磁場中で成形して得られた成形体を１１４０℃で１時間焼結し、１１００℃より６００℃までを１５分間で通過するように室温まで冷却した。ついで、この物を６００℃に１５分間保持し、３００℃まで８時間かけて時効したところ、表２Ａに示す特性を得た。すなわち、高保磁力とそのばらつきは比較的大きい。
【００９１】
また、比較例７の永久磁石を以下の方法で作製した。Ｃｅ_０．８５Ｓｍ_０．１５（Ｃｏ_{０．７０２}Ｆｅ_０．１６Ｃｕ_０．１３Ｚｒ_{０．００８}）_５．９５で与えられる組成の成型物を無磁場中で成形した。得られた成型物を比較例６と同様に１１２０℃で１時間焼結した後、１１００℃より５００℃までを約６０分で通過する如く室温まで冷却した。ひきつづき、５００℃に２０分保持した後４時間で３００℃まで徐冷した。表２Ａに示したように比較例６は保磁力が高すぎ、また比較例７は保磁力のばらつきが大きい。
【００９２】
（比較例８，９）
比較例８の永久磁石を以下の方法で作製した。表２Ａに示す合金を、アルゴンガス雰囲気中で高周波溶解し、鋳造して得られたインゴツトに１１８０℃、６時間の溶体化処理を施し、処理後、液体窒素中で急速冷却した。得られた合金を鉄乳鉢中で粗粉砕し、さらに有機溶剤中でボール・ミル微粉砕を行ない、２〜１０μｍの粉末とした。この粉末を１２ｋＯｅの磁界中でプレス成型し、圧縮成型体を得た。
【００９３】
次に、圧縮成型体を水素雰囲気中１２００℃、２時間の焼結を行ない、焼結後、１００℃／ｍｉｎの冷却速度で８００℃以下の温度まで冷却することにより、比較例８の永久磁石を得た。
【００９４】
また、比較例９の永久磁石を以下の方法で作製した。上記と同じ鋳造後のインゴツトに溶体化処理を施さずに、上記と同じ条件の粗粉砕、微粉砕、プレス成型、焼結した後、焼結後の溶体化処理を１１６０℃、８時間で行い、比較例９の永久磁石を得た。いずれも、試料を１００個作製し、磁石特性の評価結果の平均値を表２Ａに示す。
【００９５】
（比較例１０，１１）
Ｓｍ（Ｎｉ_０．１８Ｆｅ_０．１５Ｃｏ_０．５７Ｃｕ_０．１）_６．９で示される組成の合金をアルゴンガス雰囲気中で高周波溶解し、鉄乳鉢中で粗粉砕した。粗粉砕後の粉末をさらにヘキサン溶媒中でボールミル粉砕により平均粒度４μｍの微粉末にした。得られた微粉末を１２ｋＯｅの磁界中で５ｔｏｎ／ｃｍ^２の圧力で金型を用い圧縮成形した。このようにして得た圧縮体を不活性ガス雰囲気中１２２０℃の温度で２時間焼結し、ひき続いて３０℃／ｍｉｎの冷却速度で５００℃以下まで冷却した。
【００９６】
また、比較例１１では比較例１０における焼結後の冷却速度のみを１０００℃／ｍｉｎとし、その後８００℃で４時間の最適時効処理を行った。いずれも、試料を１００個作製し、磁石特性の評価結果の平均値を表２Ａに示すが、比較例１０では、保磁力８．８ｋＯｅ、比較例１１では２．３ｋＯｅであった。また、比較例１０は保磁力が大きかった。
【００９７】
（比較例１２，１３）
比較例１２の永久磁石を以下の方法で作製した。化学式Ｓｍ（Ｎｉ_０．１１Ｆｅ_０．１９Ｃｏ_０．６Ｃｕ_０．１）_６．９で示される組成の合金をアルゴンガス雰囲気中で高周波溶解し、鉄乳鉢中で粗粉砕した。粗粉砕後の粉末をさらにヘキサン溶媒中でボールミル粉砕により平均粒度２〜１０μｍの微粉末にした。得られた微粉末を１２ｋＯｅの磁界中で５ｔｏｎ／ｃｍ^２の圧力で金型を用い圧縮成形した。このようにして得た圧縮体を不活性ガス雰囲気中１２１０℃の温度で２時間焼結し、ひき続いて６０℃／ｍｉｎの冷却速度で５００℃以下まで冷却した。
【００９８】
また、比較例１３として、比較例１２における焼結後の冷却速度のみを１０００℃／ｍｉｎとし、その後、８００℃×４時間の時効処理を行った。いずれも、試料を１００個作製し、磁石特性を評価した結果、保磁力が大きすぎたり、小さすぎたりし、また保磁力のばらつきが大きかった。
【００９９】
（比較例１４，１５）
比較例１４の永久磁石を以下の方法で作製した。組成式Ｓｍ（Ｃｏ_０．６０Ｆｅ_０．１９Ｎｉ_０．１１Ｃｕ_０．１）_６．９で示される組成の合金をアルゴンガス雰囲気中で高周波溶解し、鉄乳鉢中で粗粉砕した。粗粉砕後の粉末をさらにヘキサン溶媒中でボールミル粉砕により平均粒度３μｍの微粉末にした。この微粉末を１２ｋＯｅの磁界中で５ｔｏｎ／ｃｍ^２の圧力で金型を用いた圧縮成形した。このようにして得た圧縮体を不活性ガス雰囲気中１１９０℃の温度で２時間焼結し、ひき続いて２００℃／ｍｉｎの冷却速度で５００℃以下まで冷却した。
【０１００】
また、比較例１５として、比較例１４における焼結後の冷却速度のみを１０００℃／ｍｉｎとし、その後、８００℃で２時間の最適時効処理を行った。いずれも、試料を１００個作製し、磁石特性を評価した結果、保磁力のばらつきが大きかった。
【０１０１】
（比較例１６〜３６）
表２Ａ及び表２Ｂに示す比較例１６〜３６に示す組成の合金を高周波溶解し、粗粉砕した後、ジェットミルで微粉砕した。得られた微粉末を１２ｋＯｅの磁界中で５ｔｏｎ／ｃｍ^２の圧力で金型を用い圧縮成形した。このようにして得た圧縮体を不活性ガス雰囲気中で、各合金の融点の３０℃下の温度で２時間焼結し、引き続いて３０℃／ｍｉｎの冷却速度で５００℃以下まで冷却した。その後、８００℃で４時間時効処理を行い、５℃／ｍｉｎの条件で冷却した。これらの磁石特性を評価した結果を表２Ａ及び表２Ｂにまとめる。いずれの磁石も製造時の保磁力のばらつきが多く、またリコイル透磁率が大きかった。
【０１０２】
なお、比較例２２，２３で使用するＭＭは、組成が重量比でＬａ６０Ｃｅ１０Ｐｒ２０Ｎｄ１０のミッシュメタルである。
【０１０３】
（モータへの適用）
実施例１〜３４および比較例１〜３６を永久磁石モータに組込んだ際の特性を評価した。評価温度は室温である。モータ特性の評価として各実施例および各比較例に係る永久磁石を、図２に示す全体または一部の永久磁石の磁化状態を変化させることができるモータの低保磁力磁石部に組み込み、また高保磁力磁石としてＮｄＦｅＢ磁石（Ｈｃ＝２１ｋＯｅ、Ｂｒ＝１２．４ｋＧ）を用いて、モータの効率評価を行った。なお、表２Ｂに比較例３７としてアルニコ磁石を示した。
【０１０４】
基準とする永久磁石モータは磁石として全てＮｄＦｅＢ磁石（比較例３８：低保磁力側も高保磁力側と同じ磁石を使用）を用いた場合の効率を基準とし、実施例、比較例の効率を相対値として示している。評価条件は、モータの高速回転（３０００ｒｐｍ）、中速回転（２０００ｒｐｍ）、低速回転（１０００ｒｐｍ）での効率の平均値である。これらの条件は、トルクを指標とすると低トルク、中トルク、高トルクとなっており、各動作条件での効率が反映されることになる。
【０１０５】
結果を表１Ａ，表１Ｂおよび表２Ａ，表２Ｂに併せて示すが、本実施例に係る永久磁石を用いた場合、ＮｄＦｅＢ磁石のみの永久磁石モータに比べて、大幅に効率向上しており、またアルニコ磁石を用いた場合に比べても効率が高いことがわかる。
【０１０６】
なお、今回実施例として図２に示す構造の全体または一部の永久磁石の磁化状態を変化させることができるモータへの適用を行ったが、保磁力の高い磁石と比較的保磁力の小さい磁石の組合せで構成される永久磁石モータ用磁石として本実施例の磁気特性をもつ永久磁石を使用するものであれば、特にモータ構造に制限されない。
【０１０７】
（実施例３５〜４０、比較例３９〜４０）
次に実施例１と同様の組成を用いた原料粉末を用意し、製造条件を表３のように変えて製造を行った。得られた永久磁石について実施例１と同様の磁気特性の測定を行った。その結果を表３に示す。
【表３】

【０１０８】
表３から分かるとおり、本発明の好ましい条件を満たす製造方法であれば本発明の永久磁石を効率よく得られることがわかる。また、好ましい条件を満たさない比較例３９および比較例４０では十分な特性が得られないことが分かった。
【０１０９】
なお、本実施例に用いた永久磁石モータは一例であって、インナーロータ型、アウターロータ型、またＳＰＭ型、ＩＰＭ型のいずれのタイプの永久磁石モータ（一例として、前述の図３，４に示したような構造）でも高効率化を達成することができる。
【符号の説明】
【０１１０】
１，１１，２１，４１…回転子、２，１２，２２，４２…回転子鉄心、３，２３，４３…第１の希土類永久磁石（低保磁力永久磁石）、４，２４，４４…第２の希土類永久磁石（高保磁力永久磁石）、５…第１の空洞、６…第２の空洞、７，２７，４６…鉄心の磁極部、１４…永久磁石、２６…ボルト穴、２８，４８…固定子、２９，４９…電機子巻線、３０，５０…固定子鉄心、３１，５１…エアギャップ。【Technical field】
[0001]
  The present invention relates to a permanent magnet, particularly a permanent magnet having a low coercive force and a high squareness ratio suitable for a motor, and a method for manufacturing the same. Furthermore, the present invention relates to a permanent magnet motor using these magnets.
[Background]
[0002]
  Conventionally, alnico magnets, ferrite magnets, Sm—Co magnets, Nd—Fe—B magnets, and the like are known as permanent magnets. As for these permanent magnets, appropriate magnets according to the specifications are used for key parts of various electric devices in addition to various motors such as VCM, spindle motor, measuring instrument, speaker, medical MRI and the like.
[0003]
  These magnets contain a large amount of Fe or Co and rare earth elements. Fe and Co contribute to an increase in saturation magnetic flux density. On the other hand, rare earth elements bring about a very large magnetic anisotropy derived from the behavior of 4f electrons in the crystal field, thereby contributing to an increase in coercive force and realizing good magnet characteristics.
[0004]
  In recent years, there has been an increasing demand for miniaturization and energy saving of various electric devices. Higher maximum energy product [(BH) for permanent magnets, which are key parts of these devices._maxThere has been a demand for improvement in temperature characteristics of large coercive force and magnet characteristics.
[0005]
  As an application field of permanent magnets, motors are particularly attracting attention from the viewpoint of energy saving. When used for this, the loss can be greatly reduced compared to the conventional induction type, and therefore, it is spreading as an energy saving technology for various uses such as in-vehicle and home appliance applications.
[0006]
  Generally, permanent magnet motors are roughly divided into two types. These are a surface magnet type permanent magnet motor in which a permanent magnet is attached to the outer periphery of a rotor core and an embedded type permanent magnet motor in which a permanent magnet is embedded in the rotor core. An embedded permanent magnet motor is suitable for the variable speed drive motor.
[0007]
  A configuration of a rotor of an embedded permanent magnet motor (IPM) will be described with reference to FIG. In FIG. 1, 11 is a rotor, 12 is a rotor core, and 14 is a high coercivity permanent magnet. A rectangular cavity is provided in the outer peripheral portion of the rotor core 12 by the same number as the number of poles. The rotor 11 shown in FIG. 1 is a four-pole rotor 11. The rotor core 12 is provided with four cavities, and permanent magnets 14 are inserted into the cavities. The permanent magnet 14 is magnetized in the direction perpendicular to the radial direction of the rotor or the side (long side in FIG. 1) facing the air gap surface in the rectangle of the cross section of the permanent magnet 14. The permanent magnet 14 is mainly an NdFeB permanent magnet having a high coercive force so as not to be demagnetized by a load current. The rotor core 12 is formed by laminating electromagnetic steel plates punched out of cavities. An example of such a motor is a permanent magnet type reluctance type rotating electrical machine described in JP-A-11-136912 (Patent Document 1).
[0008]
  In a permanent magnet type rotating electrical machine, the flux linkage of the permanent magnet is always generated at a constant rate. For this reason, the induced voltage by a permanent magnet becomes high in proportion to a rotational speed. When driving while changing the magnetization from low speed to high speed, the induced voltage by the permanent magnet becomes extremely high at high speed rotation. As a result, the induced voltage by the permanent magnet is applied to the electronic component of the inverter, and when the voltage exceeds the withstand voltage of the electronic component, the component breaks down. For this reason, it is conceivable to perform a design in which the amount of magnetic flux of the permanent magnet is reduced so as to be equal to or lower than the withstand voltage.
[0009]
  When the operation is performed while changing the magnetization close to the constant output from the low speed to the high speed, the interlinkage magnetic flux of the permanent magnet is constant. For this reason, in the high-speed rotation region, the voltage of the rotating electrical machine reaches the upper limit of the power supply voltage and the current necessary for output does not flow. As a result, the output is greatly reduced at high speeds, and further, it becomes impossible to drive over a wide range up to high speeds. Recently, flux-weakening control has begun to be applied as a method of expanding the operating range while changing the magnetization. In the flux weakening control, a demagnetizing field due to the d-axis current is applied to the high coercive force permanent magnet, and the magnetic operating point of the permanent magnet is moved within a reversible range to change the amount of magnetic flux. For this reason, an NdFeB magnet having a high coercive force is applied to the permanent magnet so as not to be irreversibly demagnetized by a demagnetizing field.
[0010]
  Since the interlinkage magnetic flux of the permanent magnet decreases due to the demagnetizing field of the d-axis current, the decrease of the interlinkage magnetic flux creates a voltage margin with respect to the voltage upper limit value. Since the current can be increased, the output in the high speed region increases. Further, the rotational speed can be increased by the voltage margin, and the range in which the operation can be performed while changing the magnetization is expanded.
[0011]
  However, it is necessary to continue to apply a demagnetizing field to the permanent magnet, and since the d-axis current that does not contribute to the output is continuously supplied, the copper loss increases and the efficiency deteriorates. Further, the demagnetizing field due to the d-axis current generates a harmonic magnetic flux, and the increase in voltage generated by the harmonic magnetic flux or the like is weakened, creating a limit of voltage reduction by the magnetic flux control. Therefore, even if the flux-weakening control is applied to the embedded permanent magnet type rotating electric machine, it is difficult to operate at a variable speed that is three times or more the base speed. Furthermore, the iron loss is increased by the harmonic magnetic flux, and vibration is generated by the electromagnetic force generated by the harmonic magnetic flux.
[0012]
  Further, when an embedded permanent magnet motor is applied to a drive motor for a hybrid vehicle, the motor is rotated in a state where it is driven only by an engine. At medium / high speed rotation, the induced voltage of the motor's permanent magnet exceeds the power supply voltage, and the d-axis current continues to flow under the flux-weakening control. In this state, since the motor generates only a loss, the overall operation efficiency is deteriorated. The d-axis current continues to flow, leading to a decrease in efficiency.
[0013]
  For this reason, with respect to the problems of the prior art as described above, Japanese Patent Laid-Open No. 2006-280195 (Patent Document 2) enables operation while changing the magnetization in a wide range from low speed to high speed. Motors that can change the magnetization state of all or part of permanent magnets that can provide higher torque and higher output in the middle / high-speed rotation range, improved efficiency, and improved reliability (permanent magnet type) Rotating electric machines) have been proposed.
[0014]
  That is, this permanent magnet type motor includes a stator provided with a stator winding as shown in FIG. 2 (FIG. 1 of Patent Document 2), and a magnetic field generated by a current of the stator winding in a rotor core. And a rotor in which a low coercivity permanent magnet having a coercive force with which the magnetic flux density is irreversibly changed and a high coercivity permanent magnet having a coercivity more than twice that of the low coercivity permanent magnet are provided. Is. In other words, a permanent magnet rotating electrical machine that enables variable speed operation in a wide range from low speed to high speed, realizing high torque in the low-speed rotation range, high output in the medium / high-speed rotation range, improved efficiency, and improved reliability. Can provide. As the magnet used for the permanent magnet motor, a high coercive force magnet is an NdFeB magnet, and a low coercive force magnet is an alnico magnet or an FeCrCo magnet.
[0015]
  Patent Document 2 shows an Alnico magnet (AlNiCo) or FeCrCo magnet as a low coercivity permanent magnet, and an NdFeB magnet as a high coercivity permanent magnet. The coercive force of the alnico magnet (magnetic field at which the magnetic flux density becomes 0) is 60 to 120 kA / m. It becomes 1/15 to 1/8 with respect to the coercive force 950 kA / m of the NdFeB magnet. The coercive force of the FeCrCo magnet is about 60 kA / m, which is 1/15 of the coercive force of the NdFeB magnet of 950 kA / m. Alnico magnets and FeCrCo magnets have considerably lower coercivity than NdFeB high coercivity magnets. Using this low coercive force, a motor capable of changing the magnetization state of all or part of permanent magnets is produced. In the embodiment, a high coercive force permanent magnet having a coercive force 8 to 15 times that of the low coercive force permanent magnet is applied, thereby obtaining a rotating electrical machine having excellent characteristics.
[0016]
  On the other hand, SmCo magnets aimed at developing a high coercive force have been disclosed.
[0017]
  Japanese Patent Publication No. 2-27426 (Patent Document 3) discloses a rare earth metal-containing permanent magnet alloy represented by the following general formula as an SmCo-based magnet whose maximum energy product is improved.
[0018]
    Sm_1-αCe_α(Co_1-x-y-u-v-wFe_xCu_yTi_uZr_vMn_w)_z
  In the above general formula, 0.1 ≦ α ≦ 0.90, 0.10 ≦ x ≦ 0.30, 0.05 ≦ y ≦ 0.15, 0.002 ≦ u ≦ 0.03, 0.002 ≦ v ≦ 0.03, 0.005 ≦ w ≦ 0.08, 0.01 ≦ u + v + w ≦ 0.10, 5.7 ≦ z ≦ 8.1
  Specifically, Ti, Zr, and Mn are used as essential elements, followed by sintering at 1050 to 1250 ° C., followed by solution treatment at 1050 to 1200 ° C., followed by aging at 400 to 900 ° C. for 2 to 20 hours. It is said that a high coercive force of 6.5 kOe or more can be obtained.
[0019]
  Japanese Patent Publication No. 1-2970 (Patent Document 4) discloses a manufacturing method that improves permanent magnet characteristics, that is, a high coercive force (≧ 6.5 kOe) and stabilization.
[0020]
  That is, R composed of a rare earth element R and a transition metal element M₂M₁₇Permanent magnet alloy (where R is one or a combination of two or more of Y, La, Ce, Pr, Nb, Sm and Misty metal, M is one or more of Cu and Co, Fe or Ni) The combination and a combination in which a part of M is replaced with one or more elements of Mn and Zr) are melted and cast. Next, ingot solution treatment for 1 to 1250 ° C. for 1 to 10 hours is performed, and R₂M₁₇A single phase is formed, and this is pulverized and then compression molded to form a molded body. Next, the molded body is sintered in a temperature range of 1100 to 1250 ° C. in a reduced pressure argon gas atmosphere of 50 to 350 Torr. Furthermore, after sintering in a temperature range of 1100 to 1200 ° C., a rare earth cobalt-based permanent magnet is manufactured by performing rapid cooling at 100 ° C./min or more after solution treatment and aging treatment. In this Patent Document 4, as aging treatment, in the case of one stage, 800 ° C. for 4 hours, in the case of multi-stage heat treatment, 800 ° C. for 2 hours, 700 ° C. for 4 hours, 600 ° C. for 8 hours, 500 ° C. for 16 hours It is. Under any condition, a high coercive force (≧ 6.5 kOe) is achieved.
[0021]
  In Japanese Patent Publication No. 62-45686 (Patent Document 5), a Ce-rich rare earth cobalt magnet for the purpose of providing a permanent magnet having high performance (high coercive force) and low cost is temporarily obtained at 400 to 650 ° C. by aging treatment. It is disclosed to include a step that takes 2 hours or more to 300 ° C. after holding. That is, (a) General formula: Ce_1-uSm_u(Co_1-x-y-wCu_xFe_yM_w)_z(Wherein M is at least one of Zr and Ti, 0.05 ≦ u <0.5, 0.09 ≦ x ≦ 0.14, 0.05 ≦ y ≦ 0.25, 0.003 ≦ w ≦ 0.015, 5.8 ≦ z ≦ 6.8), the step of sintering at 1100 to 1200 ° C. (b) from 1100 ° C. to 600 ° C. A method for producing a rare earth-containing permanent magnet material comprising: a step of cooling for 50 minutes, and (c) a step of aging treatment of the sintered body held at 400 ° C. to 650 ° C. for 2 hours or more to 300 ° C. It is.
[0022]
  Japanese Patent Publication No. 62-9658 (Patent Document 6) provides a rare earth cobalt permanent magnet material having a high coercive force and a high energy product, and has the following technique for the purpose of omitting an aging treatment. It is disclosed. That is, R composed of a rare earth element R and a transition metal M₂M₁₇Type magnet alloy (where R is Y, La, Ce, Pr, Nb, Sm and a combination of two or more of misty metals, M is one or more of Cu and Co, Fe or Ni) A combination and a part of M are combined with one or more elements of Mn, Ti, Nb, Zr, Ta, and Hf) and dissolved to cast. After a solution treatment at 1150 ° C. to 1210 ° C. for 1 to 12 hours, rapid cooling is performed, and the metal phase RM₇90% or more of the phase is generated. Further, the alloy is pulverized and compression molded. A manufacturing method is disclosed in which aging treatment is omitted by sintering the compression-molded body in a vacuum or in an inert atmosphere and then cooling to 800 ° C. or lower at a cooling rate of 20 to 500 ° C./min.
[0023]
  Japanese Patent Publication No. 60-53107 (Patent Document 7) discloses a technique for improving coercive force. That is, an RM comprising a rare earth component R (one or a combination of two or more of Y, Sm, Pr, Nd, Ce, etc.) and a transition metal component M (Co, Fe, Mn, Ni, Cu, etc.).₅After the composition represented by sinter is sintered, it is gradually cooled to room temperature at a rate of 10 ° C./min or less, further subjected to aging treatment at a temperature around 850 ° C., and then rapidly cooled from the aging treatment temperature to room temperature. This is a method for producing a rare earth magnet.
[Prior art documents]
[Patent Literature]
[0024]
[Patent Document 1]
JP-A-11-136912
[Patent Document 2]
JP 2006-280195 A
[Patent Document 3]
Japanese Patent Publication No. 2-27426
[Patent Document 4]
Japanese Patent Publication No. 1-2970
[Patent Document 5]
Japanese Examined Patent Publication No. 62-45686
[Patent Document 6]
Japanese Patent Publication No.62-9658
[Patent Document 7]
Japanese Patent Publication No. 60-53107
SUMMARY OF THE INVENTION
[Problems to be solved by the invention]
[0025]
  All patent documents aim at high coercive force. Therefore, the concept of the low coercivity magnet in the motor that can change the magnetization state of the whole or a part of the permanent magnets applied this time cannot be sufficiently exhibited. On the other hand, low coercivity magnets applied to motors that can change the magnetization state of all or part of permanent magnets are required to improve efficiency by controlling magnetic flux in a wider range than when using alnico magnets. It was.
[0026]
  To further increase the output, efficiency, and reliability of motors, especially motors that can change the magnetization state of all or part of permanent magnets, it is necessary to be able to set the optimum amount of magnetic flux under specified operating conditions. . An object of the present invention is to provide a permanent magnet suitable for such a setting and particularly suitable for a low coercive force magnet and a method for manufacturing the same. The present invention provides a permanent magnet that is extremely effective for increasing the efficiency of motors of various capacities, such as household appliances such as washing machines and air conditioners, in-vehicle applications, and train applications. Furthermore, it is providing the permanent magnet motor and permanent magnet for motors suitable for the above applications.
[Means for Solving the Problems]
[0027]
  The permanent magnet of the present invention satisfies the following general formula, and has a coercive force at room temperature of 0.5 kOe or more and 5.0 kOe or less, and a squareness ratio expressed by a ratio of residual magnetization to magnetization in a magnetic field of 10 kOe is 80%. It is the above.
[0028]
  General formula: Sm_1-xyCe_xR_y(Co_1-abc-dFe_aCu_bM_cT_d)_z
  However, R is at least one selected from the group consisting of La, Nd and Pr, M is at least one selected from the group consisting of Ti, Zr and Hf, and T is Mn, V, Nb, Ta, Cr, At least one selected from the group consisting of Mo, W and Ni, and the atomic ratio when Sm is 1, 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.3, 0 ≦ x + y ≦ 0.7 0.05 ≦ a ≦ 0.3, 0.02 ≦ b ≦ 0.15, 0.01 <c ≦ 0.04, 0 ≦ d ≦ 0.05, 6.0 ≦ z ≦ 8.3 .
[0029]
  The coercive force at room temperature is preferably 0.5 kOe or more and 3.5 kOe or less. The general formula a value is preferably 0.10 ≦ a ≦ 0.25, and the b value is 0.04 ≦ b ≦ 0.12. The average recoil permeability of the second and third quadrants is preferably 1.00 to 1.08. CaCu₅Phase, Th₂Zn₁₇Phase, TbCu₇It is preferable to comprise three phases. The permanent magnet is preferably a sintered body. Moreover, it is suitable for the permanent magnet mounted on the motor. In particular, the coercive force is 0.5 kOe or more and 5.0 kOe or less, the squareness ratio expressed by the ratio of the residual magnetization to the magnetization in a magnetic field of 10 kOe is 80% or more, and the average recoil permeability 1 in the second and third quadrants is 1. The permanent magnet having 0.001 to 1.08 is suitable for a motor that can change the magnetization state of the whole or part of the permanent magnet.
[0030]
  Moreover, the manufacturing method of the permanent magnet of the present invention includes a molding step of adjusting a molded body by molding an alloy powder satisfying the following general formula in a magnetic field, and the molded body in an inert atmosphere at 1000 ° C. or higher and 1200 ° C. or lower. Sintering step for obtaining a sintered body by sintering and forming a solution at a temperature of 10 minutes to 20 hours, heat-treating the sintered body at a temperature of 600 ° C. to 800 ° C. for 10 minutes to 20 hours, And an aging treatment step of cooling to 500 ° C. at a cooling rate of 1 to 10 ° C./min after the heat treatment.
[0031]
  General formula: Sm_1-xyCe_xR_y(Co_1-abc-dFe_aCu_bM_cT_d)_z
  However, R is at least one selected from the group consisting of La, Nd and Pr, M is at least one selected from the group consisting of Ti, Zr and Hf, and T is Mn, V, Nb, Ta, Cr, At least one selected from the group consisting of Mo, W and Ni, and the atomic ratio when Sm is 1, 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.3, 0 ≦ x + y ≦ 0.7 0.05 ≦ a ≦ 0.3, 0.02 ≦ b ≦ 0.15, 0.01 <c ≦ 0.04, 0 ≦ d ≦ 0.05, 6.0 ≦ z ≦ 8.3 .
[0032]
  The temperature range of the aging treatment is preferably 600 to 750 ° C. Moreover, CaCu can be obtained by aging treatment.₅Phase, Th₂Zn₁₇Phase, TbCu₇It is preferable to have a phase configuration including three phases. Moreover, it is preferable that the squareness ratio represented by the ratio of the residual magnetization to the magnetization in a magnetic field of 10 kOe with a coercive force of the permanent magnet of 0.5 kOe or more and 5.0 kOe or less is 80% or more.
[0033]
  Moreover, it is preferable to cool to room temperature or the said heat processing temperature at the cooling rate of 1-100 degrees C / min after the said sintering process.
[0034]
  A permanent magnet for a motor according to the present invention is a permanent magnet for a motor used for a motor capable of changing the magnetization state of the whole or a part of the permanent magnet,
  The coercive force at room temperature is 0.5 kOe or more and 5 kOe or less, the squareness ratio expressed by the ratio of the residual magnetization to the magnetization in a magnetic field of 10 kOe is 80% or more, and the average recoil permeability in the second and third quadrants is 1.00 or more. It is a rare earth magnet of 1.08 or less.
[0035]
  The permanent magnet motor according to the present invention has a coercive force at room temperature of not less than 0.5 kOe and not more than 5 kOe, a squareness ratio represented by a ratio of residual magnetization to magnetization in a magnetic field of 10 kOe, and 80% or more in the second and third quadrants. A first rare earth permanent magnet for changing the magnetization state, having an average recoil permeability of 1.00 to 1.08;
  A second rare earth permanent magnet having a higher coercivity at room temperature than the first rare earth permanent magnet;
It is characterized by providing.
[0036]
  Furthermore, according to the present invention, the following general formula is satisfied, and the squareness ratio expressed by the ratio of the remanent magnetization to the magnetization in a magnetic field of 10 kOe is not less than 80% and the coercive force is not less than 0.5 kOe and not more than 3.5 kOe. A permanent magnet is provided.
[0037]
  Further, according to the present invention, a molding step of adjusting a molded body by molding an alloy powder satisfying the following general formula in a magnetic field, the molded body in an inert atmosphere at a temperature of 1000 ° C. or higher and 1200 ° C. or lower for 10 minutes or longer. Sintering process for obtaining a sintered body by sintering and solution treatment for 20 hours or less, and heat-treating the sintered body at a temperature of 600 ° C. to 750 ° C. for 10 minutes to 20 hours, There is provided a method for producing a permanent magnet comprising an aging treatment step of cooling to room temperature at 10 ° C / min.
[0038]
  General formula: Sm_1-xyCe_xR_y(Co_1-abc-dFe_aCu_bM_cT_d)_z
            R: at least one selected from La, Nd, and Pr
            M: at least one selected from Ti, Zr, and Hf
            T: At least one selected from V, Nb, Ta, Cr, Mo, W, and Ni
            Atomic ratio when Sm is 1
            0 ≦ x ≦ 0.5
            0 ≦ y ≦ 0.3
            0 ≦ x + y ≦ 0.7
            0.05 ≦ a ≦ 0.3
            0.02 ≦ b ≦ 0.15
            0.01 <c ≦ 0.04
            0 ≦ d ≦ 0.05
            6.0 ≦ z ≦ 8.3
  In addition, according to the present invention, the coercive force is 0.5 kOe or more and 3.5 kOe or less, the squareness ratio represented by the ratio of the residual magnetization to the magnetization in the magnetic field of 10 kOe is 80% or more, and the average of the second and third quadrants. It has a recoil permeability of 1.00 to 1.08 and can change the magnetization state of the whole or a part of the permanent magnet, characterized in that the rare earth element mainly contains Sm and the transition metal mainly contains cobalt. A permanent magnet for a motor is provided.
【The invention's effect】
[0039]
  According to the present invention, a permanent magnet having a low coercive force and a high squareness ratio can be provided. Therefore, the low coercive force side magnet of a motor, particularly a motor capable of changing the magnetization state of the whole or a part of the permanent magnet. Is preferred. Moreover, if it is the manufacturing method of this invention, the low coercive force and the permanent magnet of a high squareness ratio can be manufactured efficiently. Furthermore, a high-efficiency permanent magnet motor can be realized by using these magnets.
[Brief description of the drawings]
[0040]
FIG. 1 is a diagram showing an example of a permanent magnet motor.
FIG. 2 is a view showing an example of a motor using the permanent magnet of the present invention.
FIG. 3 is a sectional view showing a permanent magnet motor according to the embodiment.
FIG. 4 is a cross-sectional view showing a permanent magnet motor according to another embodiment.
BEST MODE FOR CARRYING OUT THE INVENTION
[0041]
  The permanent magnet of the present invention satisfies the following general formula, and has a coercive force at room temperature of 0.5 kOe to 5.0 kOe, and a squareness ratio expressed by a ratio of residual magnetization to magnetization in a magnetic field of 10 kOe is 80%. It is the above, It is characterized by the above.
[0042]
  General formula: Sm_1-xyCe_xR_y(Co_1-abc-dFe_aCu_bM_cT_d)_z
  However, R is at least one selected from the group consisting of La, Nd and Pr, M is at least one selected from the group consisting of Ti, Zr and Hf, and T is Mn, V, Nb, Ta, Cr, At least one selected from the group consisting of Mo, W and Ni, and the atomic ratio when Sm is 1, 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.3, 0 ≦ x + y ≦ 0.7 0.05 ≦ a ≦ 0.3, 0.02 ≦ b ≦ 0.15, 0.01 <c ≦ 0.04, 0 ≦ d ≦ 0.05, and 6.0 ≦ z ≦ 8.3 .
[0043]
  First, the coercive force at room temperature is 0.5 kOe or more and 5.0 kOe or less. When the coercive force is less than 0.5 kOe, the magnetic flux control range in the motor that can change the magnetization state of the whole or a part of the permanent magnets becomes narrow. When the coercive force exceeds 5.0 kOe, a great amount of electric energy is required to reverse the magnetization of the magnet, so that the energy saving effect is greatly reduced. Therefore, it is preferably 1 to 3.5 kOe, and more preferably 1 to 3.0 kOe. When the permanent magnet motor operates at a high temperature up to 150 ° C., a high-efficiency motor can be obtained with a coercive force of up to 5 kOe. The squareness ratio is 80% or more. When the squareness ratio is less than 80%, the magnetic flux control range in the motor that can change the magnetization state of the whole or a part of the permanent magnets is narrowed. A preferable value of the squareness ratio is 90 to 100%. The squareness ratio of the present invention is a value expressed by the ratio of residual magnetization to magnetization in a magnetic field of 10 kOe. The reason why 10 kOe is selected is as follows. This is because the permanent magnet of the present invention has a low coercive force of 5 kOe or less and is almost magnetically saturated in a magnetic field of 10 kOe, which is suitable for defining the squareness ratio. In the case of a permanent magnet, the theoretical value of the maximum energy product is usually a value obtained by dividing the square of the residual magnetization by 4. Also, the squareness ratio is obtained by dividing the actual maximum energy product value by this value. On the other hand, since the permanent magnet of the present invention controls the coercive force to a relatively small value, the squareness ratio applied to the soft magnetic material was used as a reference as a new index representing the squareness.
[0044]
  The average recoil permeability of the second and third quadrants is preferably 1.00 to 1.08. In principle, recoil permeability is less than 1.00. If the recoil permeability exceeds 1.08, the magnetic flux control amount of the motor that can change the magnetization state of the whole or a part of the permanent magnets is reduced, and the range in which high-efficiency operation can be performed becomes narrow. A preferred recoil permeability is 1.07 or less.
[0045]
  The recoil permeability is obtained from a change of magnetization in the second and third quadrants by a magnetic field, for example, a change from 15 kOe to zero magnetic field using a sample vibration type magnetometer. Specifically, the magnetization measurement is performed by applying a magnetic field up to −15 kOe opposite to the direction of magnetizing the sample magnetized with a pulse magnetic field of 60 kOe and changing the strength of the magnetic field from there to 0. Thereafter, after applying a magnetic field up to −14 kOe, the magnetic field is similarly changed to zero and the magnetization is measured. This is repeated every 1 kOe and measured in the range from the third quadrant to the second quadrant. The recoil permeability approximates a straight line, and is a value obtained by dividing each magnetic field (-15 kOe, -14 kOe,...) And the magnetization difference when the magnetic field is zero by the magnetic field change amount. The average of them is the average recoil permeability.
[0046]
  The coercive force and the squareness ratio can be obtained by ordinary measurement. The coercive force is a coercive force when a full loop measurement is performed with a maximum magnetic field of 10 kOe. The squareness ratio is the remanent magnetization relative to the magnetization at 10 kOe.
[0047]
  Next, each element shown in the general formula will be described.
[0048]
  Sm is an essential element which is the basis of the permanent magnet of the present invention together with Co. Ce is an element capable of substituting the Sm site, maintains the crystal structure, and realizes the characteristics of the present invention. The amount x is 0.5 or less, and when it exceeds that, magnetization decreases. The R element is at least one selected from the group consisting of La, Pr and Nd. R element is an element effective together with Sm and Ce to control the coercive force by heat treatment. The amount x of the R element is 0.3 or less, and if this amount is exceeded, the magnetization will decrease as in the case of Ce. Among the rare earth elements of Sm, Ce, and R elements, Sm is the element that preferably has the highest content. Note that the sum of x and y is 0.7 or less. If this amount is exceeded, the squareness deteriorates and the recoil permeability increases, which is insufficient for the magnetic flux control of the variable magnetic flux type permanent magnet motor. It becomes. Among the R elements, preferred elements are Pr and La. Instead of R element or Ce, a rare earth element before separation such as misch metal or didymium may be used.
[0049]
  Fe is an element that contributes to an increase in saturation magnetization. When the amount a is less than 0.05, the effect is small, and when it exceeds 0.3, the squareness decreases and the recoil permeability increases. A preferable range of the a value is 0.10 ≦ a ≦ 0.25, and a more preferable range is 0.15 ≦ a ≦ 0.23. Cu is an essential element for controlling the coercive force.₇Phase is CaCu₅Phase and Th₂Zn₁₇It is an element that promotes phase separation into two phases. The amount b is 0.02 ≦ b ≦ 0.15. If it is 0.02 or more, the function is exhibited. More preferably, 0.04 ≦ b ≦ 0.12.
[0050]
  The M element is at least one selected from the group consisting of Ti, Zr and Hf. M element is a high temperature phase TbCu₇It is an element that promotes phase stabilization. After solution with a wide range by this element, TbCu₇It becomes easier to obtain a single phase. As a result, by performing aging treatment at a temperature of 600 ° C. to 750 ° C. for 10 minutes to 20 hours, TbCu₇Part of the phase is CaCu₅Phase and Th₂Zn₁₇TbCu formed into two phases and first formed₇It is preferable to control the coercive force while leaving the phases and to have a structure having three phases. If the amount c is less than 0.01, the effect is hardly exhibited. If the amount c exceeds 0.04, the target TbCu₇It is difficult to obtain a single phase, Th₂Ni₁₇There are too many phases, making it difficult to control coercivity and squareness.
[0051]
  The T element is at least one selected from the group consisting of Mn, V, Nb, Ta, Cr, Mo, W and Ni, and is an element effective for controlling coercive force and squareness. The amount is 0.05 or less, and if it exceeds that, the magnetization will decrease. As a result, the residual magnetization (residual magnetic flux density) is lowered, and more magnets are used to obtain a constant magnetic flux amount. Preferably, it is 0.04 or less.
[0052]
  The z value is the total atomic ratio of Co, Fe, etc. with respect to the rare earth element. With this value, TbCu is obtained by aging treatment.₇Two phases precipitated from the phase (CaCu₅Phase and Th₂Zn₁₇The ratio of the phase is different. The coercive force is controlled by a configuration having these three phases. If the z value is less than 6, it is difficult to control the coercive force. On the other hand, if the z value exceeds 8.3, the squareness ratio decreases and the recoil permeability increases, so the amount of magnetic flux that can be controlled decreases. A preferable range of the z value is 6.1 or more and 8.2 or less.
[0053]
  In the SmCo-based magnet of the above general formula, 0.001 to 0.01 wt% of B and, as unavoidable impurities, C is 0.05 wt% or less, O is 0.5 wt% or less, and Al, Si, and Ca are each 0.00%. Even if it contains 06 wt% or less and Sn is 0.005 wt% or less, it does not disturb the characteristics of the present invention.
[0054]
  In addition to the above composition, the magnet of the present invention may contain oxygen of 5000 wtppm or less, hydrogen of 2000 wtppm or less, and nitrogen of 1000 wtppm or less. In particular, when hydrogen is used in a process such as hydrogen pulverization, hydrogen may remain somewhat, but there is no problem in characteristics. Further, other components (including impurities) may be contained in a total amount of 0.1 wt% or less.
[0055]
  Although the manufacturing method of the permanent magnet of this invention is not specifically limited, The following are mentioned as a method obtained efficiently. The mother alloy is prepared at a predetermined ratio, then melted by a method such as high-frequency melting, and is produced by casting or strip casting. In the case of the casting method, it is preferable to cast on a water-cooled mold or a water-cooled metal plate in order to obtain a sufficient cooling rate. In the case of strip casting, the thickness of the obtained flakes is preferably about 70 μm or more and 2 mm or less. More preferably, it is mainly 100 μm or more and 1 mm or less. The pulverization may be finely pulverized using, for example, a jet mill, and the average particle size of the pulverized powder is preferably 1 to 15 μm. When the average particle size is 1 μm or less, it becomes difficult to obtain a sufficient sintered density, and oxidation tends to occur. On the other hand, when the average particle size exceeds 15 μm, the squareness starts to deteriorate. Preferably it is 2-12 micrometers, More preferably, it is 3-10 micrometers. On the other hand, hydrogen pulverization using hydrogen may be used, but this method may not reach a predetermined average particle size. For this reason, hydrogen storage / release may be repeated a plurality of times, or after hydrogen pulverization, further pulverization may be performed by a wet method such as a ball mill or a dry method such as a jet mill.
[0056]
  Forming in a magnetic field may be a longitudinal magnetic field or a transverse magnetic field, and the magnetic field at that time is preferably stronger in order to orient, but may be 20 kOe that is normally used. In addition, a higher molding pressure is preferable, but this is also normally used at 100 kg / cm.²That's all you need.
[0057]
  Sintering and solution treatment are first performed at room temperature to 1-50 ° C./min. The temperature is raised at a rate of 500 ° C. to 700 ° C. for 1 to 2 hours. By performing degassing, the content of gas components such as oxygen, hydrogen, and nitrogen can be reduced. Thereafter, the temperature was increased in the Ar atmosphere to a sintering temperature of 1000 to 1200 ° C. at the same temperature increase rate, and sintering was continued for a total of 10 minutes to 20 hours in this temperature range, followed by solution treatment. Further, the solution treatment is a treatment aiming at a single phase, and the treatment time is preferably about 1 to 10 hours. The solution treatment is preferably performed at the same temperature as the sintering temperature or at a temperature lower by about 20 to 30 ° C. Thereafter, 5 to 100 ° C./min. Cool at the speed of. The aging may be performed for 10 minutes to 20 hours at a temperature of 600 ° C. or higher and 800 ° C. or lower after sintering and solution treatment, and thereafter 1 to 10 ° C./min. Cool to 500 ° C. at a cooling rate of 1-10 ° C./min. The cooling rate may be up to room temperature, but considering the production efficiency, it is sufficient to control the cooling rate to 500 ° C. Between the sintering / solution treatment and the aging treatment, the treatment may be once cooled to room temperature or continuously. In addition, aging can control the coercive force by one-stage (one temperature condition) treatment, but it may be two-stage (two temperature conditions) or more treatment. In this case, it is preferable to go through a step from a higher temperature side to a lower temperature, and in this case, the cooling rate between the two temperatures is 1 to 5 ° C./min. To do. In the case of multiple stages, the entire aging time may be 20 hours or less.
[0058]
  The aging temperature is preferably 600 ° C. or higher and lower than 800 ° C., more preferably 600 ° C. or higher and 750 ° C. or lower.
[0059]
  The atmosphere in this process is preferably a non-oxidizing atmosphere, and treatment in Ar, nitrogen and vacuum is preferred. The sintered density is preferably 95% or more. The sintered density is determined by (actual measured value / theoretical density by Archimedes method) × 100%.
[0060]
  After the sintering step, it is desirable to cool at a cooling rate of 5 ° C./min to 100 ° C./min up to room temperature or the temperature of the heat treatment in the aging treatment described above. The cooling rate varies depending on whether the aging treatment, which is the next step, is performed continuously, or when aging is performed after cooling to room temperature. That is, in the case of continuous processing, if the cooling rate is too high, there is a possibility of overshooting. 10 ° C./min. The following is preferred. In the case of cooling to room temperature once, 10 ° C./min. 100 ° C./min. The following is preferred. The cooling rate is 5 ° C./min. If it is less than this, there is a possibility that an aging effect may occur, and characteristic control becomes difficult. On the other hand, 100 ° C./min. Since the cooling rate exceeding 1 is too high, the sintered body is likely to be distorted, and cracks and the like may occur.
[0061]
  The magnet obtained by the above process is CaCu with high magnetic anisotropy.₅Phase and highly saturated magnetized phase Th₂Zn₁₇Phase main phase and TbCu formed before aging treatment₇The above-described magnet characteristics can be satisfied with a configuration including three phases in which phases also remain. Therefore, TbCu can be obtained by sintering and solution treatment.₇It is important to make the phase into a single phase or a main phase.₇Highly saturated magnetization Th₂Zn₁₇Phase and high magnetic anisotropy CaCu₅The coercive force can be controlled by separating the phase into two phases. TbCu₇The phase ratio of the phase is preferably 30% or more, more preferably 50% or more by volume. TbCu₇When the phase is 100%, the coercive force is extremely small. Preferably it is 95% or less, More preferably, it is 90% or less.
[0062]
  CaCu₅Phase, Th₂Zn₁₇Phase and TbCu₇In addition to the phase, Th₂Ni₁₇The conditions under which the phase is generated depend on the composition and heat treatment conditions. Th₂Ni₁₇Since the phase has a small magnetic anisotropy constant or has in-plane magnetic anisotropy, a four-phase structure may be used. For a 4-phase configuration, Th₂Ni₁₇The amount of phase is preferably 10% or less.
[0063]
  TbCu₇Phase, CaCu₅Phase and Th₂Zn₁₇The presence or absence of a phase can be determined by XRD (X-ray diffraction method). In the present invention, it is not excluded that only each phase has a phase configuration other than three phases. The phase ratio can be determined by X-ray diffraction.
[0064]
  The evaluation method uses an X-ray diffraction method. That is, the characteristic diffraction line of each phase is obtained from the diffraction intensity. That is, TbCu₇The phase is based on the diffraction of the (200) plane in the X-ray diffraction of the single phase after solution treatment, and the ratio of the phase is obtained with a decrease in strength relative to this. On the other hand, Th₂Zn₁₇Phase, CaCu₅Phase, Th₂Ni₁₇Each single phase is separately prepared, and the phase is obtained by a relative value with respect to the diffraction intensity of each (024) plane, (110) plane, (200) plane, and (203) plane. The conditions for the X-ray diffraction measurement are 50 kV and 100 mA. Moreover, since the same result is obtained also by observation of SEM and EPMA, this method may be used.
[0065]
  On the other hand, TbCu₇When all phases are separated into two phases, a high coercive force Hc is obtained, and it is difficult to apply the present invention to a motor that can change the magnetization state of the whole or a part of permanent magnets. Therefore, preferably TbCu₇The phase is 20% or more, more preferably 30% or more.
[0066]
  In order to satisfy all of the coercive force, the squareness, the recoil permeability, and the like, the above aging conditions are preferable. If control can be performed in a shorter time, there is no problem even with heat treatment on the high temperature side exceeding 800 ° C. Considering time control in aging at the time of mass production, it is preferably less than 800 ° C., more preferably 790 ° C. or less.
[0067]
  The obtained magnet has excellent oxidation resistance, but it can be used in a wide variety of environments by performing various surface treatments such as Ni plating, Cu plating, and Al plating in order to provide further oxidation resistance. I can do it.
[0068]
  Moreover, in order to obtain a magnetic flux suitable for the operation mode, the permanent magnet motor using the permanent magnet according to the present invention reverses the magnetization direction of some magnets and controls the amount of magnetic flux, thereby improving the efficiency. It is intended. That is, the permanent magnet motor has a coercive force at room temperature of 0.5 kOe or more and 5 kOe or less, a squareness ratio represented by a ratio of residual magnetization to magnetization in a magnetic field of 10 kOe, and an average recoil of the second and third quadrants. A first rare earth permanent magnet having a magnetic permeability of 1.00 or more and 1.08 or less and a second rare earth permanent magnet having a room temperature coercivity higher than that of the first rare earth permanent magnet; Is provided. The first rare earth permanent magnet is a low coercivity magnet that reverses the magnetization direction to control the magnetic flux. The first rare earth permanent magnet is preferably in the range of 5 to 70% of the total magnet volume. By setting it as such a range, the output of a motor, efficiency, and reliability can be improved. Preferably it is 10-67%, More preferably, it is 15-50%.
[0069]
  The coercive force at room temperature of the first rare earth permanent magnet is desirably 0.5 kOe or more and 3.5 kOe or less. The first rare earth permanent magnet preferably has a composition containing a rare earth element containing Sm and a transition metal element containing Co as a main component. A more preferable composition is a composition represented by the general formula described above.
[0070]
  An example of the second rare earth permanent magnet is an NdFeB magnet.
[0071]
  The permanent magnet motor of the present invention may be either an inner rotor type or an outer rotor type, and may have either a surface magnet type (SPM) or an embedded magnet type (IPM). As the surface magnet type (SPM), for example, a permanent magnet including a first rare earth permanent magnet and a second rare earth permanent magnet can be provided on the surface or inner peripheral surface of the rotor. An example of the embedded magnet type (IPM) is one in which a permanent magnet including a first rare earth permanent magnet and a second rare earth permanent magnet is embedded in a rotor.
[0072]
  As an example, an inner rotor type IPM type is shown in FIG. As shown in FIG. 2, the rotor 1 includes a rotor core 2, a plurality of first rare earth permanent magnets (low coercivity permanent magnets) 3, and a plurality of second rare earth permanent magnets (high coercivity permanent magnets) 4. It is configured. The first rare earth permanent magnet 3 and the second rare earth permanent magnet 4 are embedded in the rotor core 2 and arranged in the circumferential direction of the rotor 1. The first cavity 5 is provided at both ends of the first rare earth permanent magnet 3. The second cavity 6 is provided at both ends of the second rare earth permanent magnet 4. Reference numeral 7 denotes a magnetic pole portion of the rotor core 2.
[0073]
  3 and 4 show an embodiment of an outer rotor type IPM type permanent magnet motor. As shown in FIG. 3, the rotor 21 in the permanent magnet motor of this embodiment includes a rotor core 22, a first rare earth permanent magnet 23, and a second rare earth permanent magnet 24. The rotor core 22 is configured by stacking silicon steel plates, for example. Four first rare earth permanent magnets 23 and two second rare earth permanent magnets 24 are embedded in the radial cross section of the rotor core 22. The first rare earth permanent magnet 23 is disposed along the radial direction of the rotor 21 and has a trapezoidal cross section. The magnetization direction of the first rare earth permanent magnet 23 is substantially the circumferential direction. The second rare earth permanent magnet 24 is disposed substantially in the circumferential direction and has a rectangular cross section. The magnetization direction of the second rare earth permanent magnet 24 is substantially the radial direction.
[0074]
  A cavity 25 is provided at each end of each of the first rare earth permanent magnet 23 and the second rare earth permanent magnet 24. The bolt hole 26 is opened in the rotor core 22. The magnetic pole core 27 of the rotor core 22 is formed so as to be surrounded by the two first rare earth permanent magnets 23 and the one second rare earth permanent magnet 24. The central axis direction of the magnetic core part 27 of the rotor core 22 is the d axis, and the central axis direction between the magnetic poles is the q axis. Accordingly, the first rare earth permanent magnet 23 is arranged in the q-axis direction which is the central axis between the magnetic poles, and the magnetization direction of the first rare earth permanent magnet 23 is 90 ° or 90 ° with respect to the q axis. In the adjacent first rare earth permanent magnets 23, the magnetic pole faces facing each other are the same. The second rare earth permanent magnet 24 is disposed in a direction perpendicular to the d axis that is the central axis of the magnetic pole core 27, and the magnetization direction is 0 ° or 180 ° with respect to the d axis. In the adjacent second rare earth permanent magnet 24, the directions of the magnetic poles are opposite to each other.
[0075]
  Such a rotor 21 is housed inside the stator 28. The stator 28 is configured by housing the armature winding 29 in a slot formed inside the stator core 30. The inner peripheral surface of the stator 28 and the outer peripheral surface of the rotor 21 are opposed to each other through an air gap 31.
[0076]
  On the other hand, as shown in FIG. 4, the rotor 41 in the permanent magnet motor of the present embodiment has a first rare earth permanent magnet 43 and a second rare earth permanent magnet 44 embedded in a rotor core 42. It is a configuration. The rotor core 42 is configured by laminating silicon steel plates. Eight first rare earth permanent magnets 43 and two second rare earth permanent magnets 44 are embedded in the radial cross section of the rotor core 42. Each of the eight sets of the first rare earth permanent magnet 43 and the second rare earth permanent magnet 44 is installed in a convex shape on the inner diameter side of the rotor 41. The magnetization directions of the first rare earth permanent magnet 43 and the second rare earth permanent magnet 44 are both substantially smaller in magnet size. If necessary, both ends of the first rare earth permanent magnet 43 and the second rare earth permanent magnet 44 may be provided with a magnetic flux short circuit and a cavity 45 for stress relaxation. The magnetic core 46 of the rotor core 42 is formed so as to be surrounded by the first rare earth permanent magnet 43 and the second rare earth permanent magnet 44. Reference numeral 47 denotes a rotating shaft.
[0077]
  Such a rotor 41 is accommodated in the stator 48. The stator 48 is configured by accommodating the armature winding 49 in a slot formed inside the stator core 50. The inner peripheral surface of the stator 48 and the outer peripheral surface of the rotor 41 are opposed to each other through an air gap 51.
[0078]
  The permanent magnet motor used by this invention is not limited to the form shown in FIGS. The present invention is applicable to a permanent magnet motor in which a plurality of permanent magnets are regularly arranged. Permanent magnets are arranged in the circumferential direction of the rotor, and magnets with high coercive force and low coercive force are alternated or the number or thickness is changed so that the volume ratio is within the above range. It can be a magnet motor.
[0079]
  The effects of the invention will be shown below by examples.
[0080]
(Example)
(Examples 1-34)
  About the composition shown to Table 1A and Table 1B, after preparing raw material powder, it melt | dissolved in the high frequency induction heating furnace, and it casted on the water-cooled copper plate, and was set as the mother alloy. The obtained sample was coarsely pulverized and then finely pulverized with a jet mill to an average particle size of 3 to 5 μm to obtain a predetermined shape with a magnetic field of 20 kOe and a press pressure of 0.5 t / cm.²Molding was performed in a magnetic field under the following conditions. The obtained molded body is sintered at a temperature 50 ° C. lower than the melting point of the parent phase (1040 to 1200 ° C.) for 3 hours, and subsequently held at a temperature 20 to 30 ° C. lower than the sintering temperature for 1 hour. Then, the solution was treated and cooled to room temperature at a rate of 50 ° C./min. Thereafter, the aging treatment of the odd-numbered examples was performed by performing heat treatment at 700 ° C. for 3 hours and then cooling at a rate of 10 ° C./min. The first-stage aging treatment of the even-numbered examples was performed at 670 ° C. for 4 hours and then to 600 ° C. at 5 ° C./min. By cooling at a rate of The second-stage aging treatment of the even-numbered examples was performed by holding at 600 ° C. for 2 hours and then cooling at a rate of 10 ° C./min. The rate of temperature increase to the aging treatment temperature is 30 ° C./min. Unified. The cooling rate in the aging treatment was from the heat treatment temperature to 500 ° C., and then natural cooling was performed.
[0081]
  Further, the temperature rise until sintering is performed at 5 ° C./min in a vacuum, once kept at 600 ° C. for degassing, and thereafter all in an Ar atmosphere.
[0082]
  In any case, 100 samples were prepared, and the residual magnetic flux density (Br), the coercive force (Hc), the squareness ratio, the recoil permeability, and the Hc range were measured as evaluation of the magnet characteristics. The residual magnetic flux density (Br), the coercive force (Hc), the squareness ratio, and the recoil permeability were measured using the method described above, and the average value of 100 pieces was obtained. The Hc range shows the variation in coercive force, and was obtained from “maximum value−minimum value” of 100 coercive forces (Hc). The results are shown in Table 1A and Table 1B.
[0083]
  Each sample was subjected to X-ray diffraction measurement (Cukα, tube voltage: 50 kV, tube current: 100 mA) to evaluate the phase configuration. In Table 1A and Table 1B, ◎ (CaCu₅Phase, Th₂Zn₁₇Phase, TbCu₇Phase, and Th₂Ni₁₇4 phases are detected), ○ (CaCu₅Phase, Th₂Zn₁₇Phase, TbCu₇3 phases are detected), x (CaCu₅Phase and Th₂Zn₁₇Detects two phases), ▲ (CaCu₅Phase, Th₂Zn₁₇Phase and Th₂Ni₁₇3 phases are detected), ■ (Th₂Zn₁₇Phase detected), □ (Th₂Ni₁₇Phase detected), △ (TbCu₇The phase was detected).
[Table 1A]

[Table 1B]

[0084]
  As can be seen from Tables 1A and 1B, it was found that the permanent magnet according to the present example has a coercive force that is neither too high nor too small, variation in coercive force is small, and recoil permeability is also small. Moreover, all were 98% or more of sintered density.
[0085]
  (Comparative example)
  Tables 2A and 2B show comparative examples.
[Table 2A]

[Table 2B]

[0086]
(Comparative Examples 1, 2, 3)
  For the compositions shown in Table 2A, the ingots of Comparative Examples 1, 2, and 3 obtained by high-frequency dissolution were pulverized to a particle size of 1 to 5 μm with a brown mill and then molded in a magnetic field. The molded body was sintered in vacuum, cooled, and then melted again at 1100 ° C. After aging at 850 ° C for 2 hours, the molded body was cooled to 500 ° C at a rate of 0.5 ° C / min, and subjected to aging treatment. It was. As a result of evaluating the magnetic characteristics, as shown in Table 2A, those having a high coercive force were obtained.
[0087]
(Comparative Examples 4 and 5)
  An alloy consisting of Sm 26.0 wt% with a purity of 99.9% or more, Co 47.3 wt%, Fe 12.8 wt%, Ni 5.3 wt%, and Cu 8.6 wt% with a purity of 99.8% is high-frequency melted and cast in an argon atmosphere. did. Table 2A shows the composition ratio of the alloy in terms of atomic ratio. The obtained alloy was subjected to ingot solution treatment at 1180 ° C. for 4 hours in an argon atmosphere. After the solution treatment, the alloy was cooled with liquid nitrogen at a cooling rate of 1200 ° C./min. And cooled quickly. Next, the obtained sample was coarsely pulverized in an iron mortar, and then made into a fine powder having an average particle size of 4 μm by a ball mill in an organic solvent. The obtained fine powder was pressed in a magnetic field of 15 kOe to form a compression molded body.
[0088]
  This compression-molded body is sintered at 1210 ° C. for 2 hours in an argon atmosphere of 200 Torr, followed by 1190 ° C. for 2 hours after solution treatment, followed by rapid cooling at a cooling rate of 150 ° C./min. did. Further, an aging treatment was performed at 800 ° C. for 4 hours to obtain Comparative Example 4. Moreover, the permanent magnet of the comparative example 5 was obtained with the manufacturing method similar to the said comparative example 4 without performing the ingot solution treatment of 1180 degreeC for 4 hours.
[0089]
  In Comparative Example 4, a coercive force of 6.5 kOe was obtained, while in Comparative Example 5, a coercive force of 4.3 kOe was obtained. In particular, in Comparative Example 5, the variation in coercive force was large.
[0090]
(Comparative Examples 6 and 7)
  The permanent magnet of Comparative Example 6 was produced by the following method. Ce_0.56Sm_0.44(Co_0.697Cu_0.13Fe_0.16Zr_0.013)_6.2The molded body obtained by molding the powder having the composition given in No. 1 in a magnetic field was sintered at 1140 ° C. for 1 hour, and then cooled to room temperature so that the temperature from 1100 ° C. to 600 ° C. was passed in 15 minutes. Next, this product was held at 600 ° C. for 15 minutes and aged to 300 ° C. over 8 hours. The characteristics shown in Table 2A were obtained. That is, the high coercive force and its variation are relatively large.
[0091]
  Moreover, the permanent magnet of Comparative Example 7 was produced by the following method. Ce_0.85Sm_0.15(Co_0.702Fe_0.16Cu_0.13Zr_0.008)_5.95The molded product having the composition given in (1) was molded in the absence of a magnetic field. The obtained molded product was sintered at 1120 ° C. for 1 hour in the same manner as in Comparative Example 6, and then cooled to room temperature so as to pass from 1100 ° C. to 500 ° C. in about 60 minutes. Subsequently, after maintaining at 500 ° C. for 20 minutes, it was gradually cooled to 300 ° C. in 4 hours. As shown in Table 2A, Comparative Example 6 has too high coercive force, and Comparative Example 7 has a large variation in coercive force.
[0092]
(Comparative Examples 8 and 9)
  The permanent magnet of Comparative Example 8 was produced by the following method. The alloy shown in Table 2A was melted at high frequency in an argon gas atmosphere, and an ingot obtained by casting was subjected to a solution treatment at 1180 ° C. for 6 hours. After the treatment, the alloy was rapidly cooled in liquid nitrogen. The obtained alloy was coarsely pulverized in an iron mortar, and further ball milled in an organic solvent to obtain a powder of 2 to 10 μm. This powder was press-molded in a magnetic field of 12 kOe to obtain a compression molded body.
[0093]
  Next, the compression molded body was sintered in a hydrogen atmosphere at 1200 ° C. for 2 hours, and after sintering, the permanent magnet of Comparative Example 8 was cooled to a temperature of 800 ° C. or less at a cooling rate of 100 ° C./min. Got.
[0094]
  Moreover, the permanent magnet of Comparative Example 9 was produced by the following method. Without subjecting the ingot after casting as described above to solution treatment, coarse pulverization, fine pulverization, press molding and sintering under the same conditions as described above, followed by solution treatment after sintering at 1160 ° C. for 8 hours. A permanent magnet of Comparative Example 9 was obtained. In any case, 100 samples were prepared, and the average values of the evaluation results of the magnet characteristics are shown in Table 2A.
[0095]
(Comparative Examples 10 and 11)
  Sm (Ni_0.18Fe_0.15Co_0.57Cu_0.1)_6.9The alloy having the composition represented by the above was melted at high frequency in an argon gas atmosphere and coarsely pulverized in an iron mortar. The coarsely pulverized powder was further made into a fine powder having an average particle size of 4 μm by ball milling in a hexane solvent. The obtained fine powder was 5 ton / cm in a magnetic field of 12 kOe.²Compression molding was performed using a mold at a pressure of. The compressed body thus obtained was sintered in an inert gas atmosphere at a temperature of 1220 ° C. for 2 hours, and subsequently cooled to 500 ° C. or less at a cooling rate of 30 ° C./min.
[0096]
  In Comparative Example 11, only the cooling rate after sintering in Comparative Example 10 was set to 1000 ° C./min, and then optimum aging treatment was performed at 800 ° C. for 4 hours. In all cases, 100 samples were prepared, and the average value of the evaluation results of the magnet characteristics is shown in Table 2A. In Comparative Example 10, the coercive force was 8.8 kOe, and in Comparative Example 11, it was 2.3 kOe. In Comparative Example 10, the coercive force was large.
[0097]
(Comparative Examples 12 and 13)
  The permanent magnet of Comparative Example 12 was produced by the following method. Chemical formula Sm (Ni_0.11Fe_0.19Co_0.6Cu_0.1)_6.9The alloy having the composition represented by the above was melted at high frequency in an argon gas atmosphere and coarsely pulverized in an iron mortar. The coarsely pulverized powder was further made into a fine powder having an average particle size of 2 to 10 μm by ball milling in a hexane solvent. The obtained fine powder was 5 ton / cm in a magnetic field of 12 kOe.²Compression molding was performed using a mold at a pressure of. The compressed body thus obtained was sintered in an inert gas atmosphere at a temperature of 1210 ° C. for 2 hours and then cooled to 500 ° C. or less at a cooling rate of 60 ° C./min.
[0098]
  Moreover, as Comparative Example 13, only the cooling rate after sintering in Comparative Example 12 was set to 1000 ° C./min, and then an aging treatment was performed at 800 ° C. × 4 hours. In any case, 100 samples were prepared and the magnetic characteristics were evaluated, and as a result, the coercive force was too large or too small, and the coercive force variation was large.
[0099]
(Comparative Examples 14 and 15)
  The permanent magnet of Comparative Example 14 was produced by the following method. Composition formula Sm (Co_0.60Fe_0.19Ni_0.11Cu_0.1)_6.9The alloy having the composition represented by the above was melted at high frequency in an argon gas atmosphere and coarsely pulverized in an iron mortar. The coarsely pulverized powder was further made into a fine powder having an average particle size of 3 μm by ball milling in a hexane solvent. This fine powder is 5 ton / cm in a magnetic field of 12 kOe.²Compression molding using a mold at a pressure of The compressed body thus obtained was sintered in an inert gas atmosphere at a temperature of 1190 ° C. for 2 hours, and subsequently cooled to 500 ° C. or less at a cooling rate of 200 ° C./min.
[0100]
  Moreover, as Comparative Example 15, only the cooling rate after sintering in Comparative Example 14 was set to 1000 ° C./min, and then an optimal aging treatment was performed at 800 ° C. for 2 hours. In any case, as a result of producing 100 samples and evaluating the magnet characteristics, the variation in coercive force was large.
[0101]
(Comparative Examples 16 to 36)
  Alloys having the compositions shown in Comparative Examples 16 to 36 shown in Table 2A and Table 2B were melted at high frequency, coarsely pulverized, and then finely pulverized with a jet mill. The obtained fine powder was 5 ton / cm in a magnetic field of 12 kOe.²Compression molding was performed using a mold at a pressure of. The compressed body thus obtained was sintered in an inert gas atmosphere at a temperature 30 ° C. below the melting point of each alloy for 2 hours, and subsequently cooled to 500 ° C. or less at a cooling rate of 30 ° C./min. Thereafter, an aging treatment was performed at 800 ° C. for 4 hours, and cooling was performed at 5 ° C./min. The results of evaluating these magnet characteristics are summarized in Tables 2A and 2B. All the magnets had a large variation in coercive force at the time of manufacture, and the recoil permeability was large.
[0102]
  The MM used in Comparative Examples 22 and 23 is a misch metal whose composition is La60Ce10Pr20Nd10 by weight.
[0103]
(Application to motor)
  The characteristics when Examples 1-34 and Comparative Examples 1-36 were incorporated in a permanent magnet motor were evaluated. The evaluation temperature is room temperature. As an evaluation of the motor characteristics, the permanent magnets according to the respective examples and comparative examples are incorporated in the low coercive force magnet portion of the motor capable of changing the magnetization state of all or part of the permanent magnets shown in FIG. Using a NdFeB magnet (Hc = 21 kOe, Br = 12.4 kG) as a magnetic magnet, the efficiency of the motor was evaluated. In Table 2B, an alnico magnet is shown as Comparative Example 37.
[0104]
  The permanent magnet motors used as references are all based on the efficiency when using NdFeB magnets (Comparative Example 38: the same magnet as the low coercive force side is used for the low coercive force side) as the reference, and the relative efficiency of the example and comparative example Shown as a value. The evaluation condition is an average value of efficiency at high speed rotation (3000 rpm), medium speed rotation (2000 rpm), and low speed rotation (1000 rpm) of the motor. These conditions are low torque, medium torque, and high torque when torque is used as an index, and the efficiency under each operating condition is reflected.
[0105]
  The results are shown in Table 1A, Table 1B, Table 2A, and Table 2B. When the permanent magnet according to this example is used, the efficiency is significantly improved as compared with a permanent magnet motor using only NdFeB magnets. In addition, it can be seen that the efficiency is higher than the case of using an alnico magnet.
[0106]
  In addition, although applied to the motor which can change the magnetization state of the whole or a part of permanent magnet of the structure shown in FIG. 2 as an embodiment this time, a magnet having a high coercive force and a magnet having a relatively small coercive force. As long as the permanent magnet having the magnetic characteristics of the present embodiment is used as a permanent magnet motor magnet constituted by the combination, the motor structure is not particularly limited.
[0107]
(Examples 35-40, Comparative Examples 39-40)
  Next, raw material powders having the same composition as in Example 1 were prepared, and the production conditions were changed as shown in Table 3 for production. The obtained permanent magnet was measured for the same magnetic properties as in Example 1. The results are shown in Table 3.
[Table 3]

[0108]
  As can be seen from Table 3, it can be understood that the permanent magnet of the present invention can be obtained efficiently if the production method satisfies the preferable conditions of the present invention. In addition, it was found that sufficient characteristics cannot be obtained in Comparative Example 39 and Comparative Example 40 that do not satisfy the preferable conditions.
[0109]
  Note that the permanent magnet motor used in this embodiment is an example, and any type of permanent magnet motor of inner rotor type, outer rotor type, SPM type, or IPM type (for example, in FIGS. High efficiency can be achieved even with the structure shown).
[Explanation of symbols]
[0110]
  1, 11, 21, 41 ... rotor, 2, 12, 22, 42 ... rotor core, 3, 23, 43 ... first rare earth permanent magnet (low coercive force permanent magnet), 4, 24, 44 ... first 2 rare earth permanent magnets (high coercive force permanent magnets), 5 ... first cavity, 6 ... second cavity, 7, 27, 46 ... magnetic pole part of iron core, 14 ... permanent magnet, 26 ... bolt hole, 28,48 ... Stator, 29, 49 ... Armature winding, 30, 50 ... Stator core, 31, 51 ... Air gap.

Claims (24)

In addition to satisfying the following general formula, the coercivity at room temperature is 0.5 kOe or more and 5.0 kOe or less, and the squareness ratio expressed by the ratio of the residual magnetization to the magnetization in a magnetic field of 10 kOe is 80% or more, and CaCu ₅ A permanent magnet comprising three phases of a phase, a Th ₂ Zn ₁₇ phase and a TbCu ₇ phase.
General formula: Sm _1-xy Ce _x R _y (Co _1-ab-c-D Fe _a Cu _{b Mc} T _d ) _z
However, R is at least one selected from the group consisting of La, Nd and Pr, M is at least one selected from the group consisting of Ti, Zr and Hf, and T is Mn, V, Nb, Ta, Cr, At least one selected from the group consisting of Mo, W and Ni, and the atomic ratio when Sm is 1, 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.3, 0 ≦ x + y ≦ 0.7 0.05 ≦ a ≦ 0.3, 0.02 ≦ b ≦ 0.15, 0.01 <c ≦ 0.04, 0 ≦ d ≦ 0.05, and 6.0 ≦ z ≦ 8.3 .   The permanent magnet according to claim 1, wherein the coercive force is 0.5 kOe or more and 3.5 kOe or less. Claim 1 or 2 permanent magnet according a value of the general formula 0.10 ≦ a ≦ 0.25, b value is equal to or is 0.04 ≦ b ≦ 0.12. The permanent magnet according to any one of claims 1 to 3 , wherein the average recoil permeability in the second and third quadrants is 1.00 or more and 1.08 or less. CaCu _{5 phase,} Th 2 _{Zn 17} phase, TbCu ₇ phase, and _Th 2 claims 1-4 permanent magnet according to any one, characterized by comprising a four-phase _{Ni 17} phase. Claim 1-5 permanent magnet according to any one of which is a sintered body. Permanent magnet according to claim 1-6 any one, characterized in that mounted on the motor. The coercive force at room temperature is 0.5 kOe or more and 5 kOe or less, the squareness ratio represented by the ratio of the residual magnetization to the magnetization in a magnetic field of 10 kOe is 80% or more, and the CaCu ₅ phase, Th ₂ Zn ₁₇ phase and TbCu _A method for producing a permanent magnet including three phases of _seven phases,
A molding process for adjusting a molded body by molding an alloy powder satisfying the following general formula in a magnetic field;
A sintering step of obtaining a sintered body by sintering and solution forming the molded body in an inert atmosphere at a temperature of 1000 ° C. to 1200 ° C. for 10 minutes to 20 hours;
An aging treatment step of heat-treating the sintered body at a temperature of 600 ° C. to 800 ° C. for 10 minutes to 20 hours and cooling to 500 ° C. at a cooling rate of 1 ° C./min to 10 ° C./min after the heat treatment; The manufacturing method of the permanent magnet characterized by comprising.
General formula: Sm _1-xy Ce _x R _y (Co _1-ab-c-D Fe _a Cu _{b Mc} T _d ) _z
However, R is at least one selected from the group consisting of La, Nd and Pr, M is at least one selected from the group consisting of Ti, Zr and Hf, and T is Mn, V, Nb, Ta, Cr, At least one selected from the group consisting of Mo, W and Ni, and the atomic ratio when Sm is 1, 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.3, 0 ≦ x + y ≦ 0.7 0.05 ≦ a ≦ 0.3, 0.02 ≦ b ≦ 0.15, 0.01 <c ≦ 0.04, 0 ≦ d ≦ 0.05, and 6.0 ≦ z ≦ 8.3 . The method for manufacturing a permanent magnet according to claim 8 , wherein the heat treatment in the aging treatment step is performed at a temperature of 600 ° C or higher and 750 ° C or lower for 10 minutes or longer and 20 hours or shorter. 10. The permanent magnet manufacturing method according to claim 8, wherein the aging treatment step forms a phase structure including four phases of CaCu ₅ phase, Th ₂ Zn ₁₇ phase, TbCu ₇ phase, and Th ₂ Ni ₁₇ phase. Method. The method for producing a permanent magnet according to any one of claims 8 to 10, wherein, after the sintering step, cooling to room temperature or the temperature of the heat treatment is performed at a cooling rate of 5 ° C / min to 100 ° C / min. . Claim coercive force at room temperature of the permanent magnets is more than 0.5 kOe 3.5 kOe or less, and squareness ratio, expressed as the ratio of residual magnetization for magnetization at a magnetic field of 10kOe is equal to or less than 80% 8 The manufacturing method of the permanent magnet of any one of -11 . A permanent magnet for a motor used in a motor capable of changing the magnetization state of all or part of permanent magnets,
The coercive force at room temperature is 0.5 kOe or more and 5 kOe or less, the squareness ratio expressed by the ratio of the residual magnetization to the magnetization in a magnetic field of 10 kOe is 80% or more, and the average recoil permeability in the second and third quadrants is 1.00 or more. A permanent magnet for a motor, which is a rare earth magnet of 1.08 or less. The permanent magnet for motor according to claim 13, wherein the coercive force at room temperature is 0.5 kOe or more and 3.5 kOe or less. 15. The permanent magnet for motor according to claim 13 , wherein the rare earth magnet contains a rare earth element containing Sm and a transition metal element containing Co as a main component. The coercive force at room temperature is 0.5 kOe or more and 5 kOe or less, the squareness ratio expressed by the ratio of the residual magnetization to the magnetization in a magnetic field of 10 kOe is 80% or more, and the average recoil permeability in the second and third quadrants is 1.00 or more. A first rare earth permanent magnet for changing a magnetization state, which is 1.08 or less;
A permanent magnet motor comprising: a second rare earth permanent magnet having a coercivity at room temperature higher than that of the first rare earth permanent magnet. The permanent magnet motor according to claim 16 , wherein the coercive force of the first rare earth permanent magnet is 0.5 kOe or more and 3.5 kOe or less. 18. The permanent magnet motor according to claim 16, wherein the first rare earth permanent magnet includes a rare earth element containing Sm and a transition metal element containing Co as a main component. 19. The permanent magnet motor according to claim 16 , wherein a ratio of the first rare earth permanent magnet to a total magnet volume is 5% or more and 70% or less. The permanent magnet motor according to any one of claims 16 to 19, wherein the permanent magnet motor is an inner rotor system or an outer rotor system. The permanent magnet motor according to any one of claims 16 to 19, further comprising a rotor in which the first rare earth permanent magnet and the second rare earth permanent magnet are arranged in a circumferential direction. The permanent magnet motor according to any one of claims 16 to 19, further comprising a rotor in which the first rare earth permanent magnet and the second rare earth permanent magnet are embedded. The permanent magnet motor according to any one of claims 16 to 19, further comprising a rotor on which the first rare earth permanent magnet and the second rare earth permanent magnet are installed. The first rare earth permanent magnet and the permanent magnet motor according to claim 16 to 19, wherein any one, characterized by further comprising a rotor to which the second rare-earth permanent magnet is installed on the inner peripheral surface.

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