JP6176712B2 - Rare earth magnet powder - Google Patents
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Description
本発明は、希土類磁石粉末、特にＳｍ−Ｆｅ−Ｎ系材料から構成される磁石粉末およびその製造方法に関する。 The present invention relates to a rare earth magnet powder, particularly a magnet powder composed of an Sm—Fe—N-based material and a method for producing the same.
希土類磁石は、磁束密度が高く極めて強力な永久磁石として、種々の用途に用いられている。代表的な希土類磁石として、Ｎｄ２Ｆｅ１４Ｂを主相とするネオジム磁石が知られている。このネオジム磁石には、一般的に耐熱性および保磁力を強化するためにジスプロシウムが添加されている。しかしながら、ジスプロシウムは希少な希土類元素であることに加え、産出地が限られているため価格が安定せず、できるだけジスプロシウムを用いない希土類磁石が求められている。 Rare earth magnets are used for various applications as extremely strong permanent magnets with high magnetic flux density. As a typical rare earth magnet, a neodymium magnet having Nd 2 Fe 14 B as a main phase is known. In general, dysprosium is added to the neodymium magnet to enhance heat resistance and coercive force. However, dysprosium is a rare rare earth element, and since the production area is limited, the price is not stable, and there is a demand for a rare earth magnet that does not use dysprosium as much as possible.
このような状況下、ジスプロシウムを用いない希土類磁石として、希土類としてＳｍを用いた磁石が注目されている。このようなＳｍを含む磁石としては、Ｓｍ−Ｆｅ−Ｎ系磁石が知られている（特許文献１）。また、このような磁石の粉末の製造方法として、原料のＳｍ−Ｆｅ金属合金粉末、Ｓｍの酸化物および還元剤を、還元拡散法により処理する方法が知られている（特許文献２）。 Under such circumstances, as a rare earth magnet not using dysprosium, a magnet using Sm as a rare earth attracts attention. As such a magnet containing Sm, an Sm-Fe-N magnet is known (Patent Document 1). As a method for producing such magnet powder, a method of treating raw material Sm—Fe metal alloy powder, Sm oxide and reducing agent by a reduction diffusion method is known (Patent Document 2).
特許文献２に記載の方法では、母合金を粉砕して原料粉末を作るため、原料粉末はほぼ単結晶でできており、結晶粒径は粉体の粒径と同程度になる。そのため原料粉末の粒径が１０μｍ以上になると必要な保磁力が得られない問題がある。一方、ボンド磁石に適用する場合、充填性の点で粉末の粒径は大きいのが望ましい。磁石粉末の粒径が１０μｍより小さくなると磁石粉末の樹脂への充填性が低下し、ボンド磁石の飽和磁束密度が低下する。また、粉末の粒径が１０μｍより小さくなると発火の危険も生じる。 In the method described in Patent Document 2, since the raw material powder is made by pulverizing the master alloy, the raw material powder is almost made of a single crystal, and the crystal grain size is about the same as the particle size of the powder. Therefore, there is a problem that a necessary coercive force cannot be obtained when the particle size of the raw material powder is 10 μm or more. On the other hand, when applied to a bonded magnet, it is desirable that the particle size of the powder be large in terms of filling properties. When the particle size of the magnet powder is smaller than 10 μm, the filling property of the magnet powder into the resin is lowered and the saturation magnetic flux density of the bonded magnet is lowered. Moreover, when the particle size of the powder is smaller than 10 μm, there is a risk of ignition.
したがって、本発明は、粉末粒径が比較的大きくても高い保磁力を有し得るＳｍ−Ｆｅ−Ｎ系材料から構成される磁石粉末を提供することを目的とする。 Accordingly, an object of the present invention is to provide a magnet powder composed of an Sm—Fe—N-based material that can have a high coercive force even if the powder particle size is relatively large.
本発明者は、上記問題を解消すべく鋭意検討した結果、Ｓｍ−Ｆｅ−Ｎ系材料から構成される磁石粉末において、粉末を多結晶化または微細組織化して主相の平均結晶粒径を小さくし、主相の他に存在するＦｅ相を所定の割合とすることにより、粉末粒径が比較的大きくても高い保磁力を達成できることを見出した。 As a result of diligent investigations to solve the above problems, the present inventors have made the magnetic powder composed of the Sm-Fe-N-based material into a polycrystal or fine structure to reduce the average crystal grain size of the main phase. The inventors have found that a high coercive force can be achieved even when the powder particle size is relatively large by setting the Fe phase present in addition to the main phase to a predetermined ratio.
本発明の第１の要旨によれば、Ｓｍ−Ｆｅ−Ｎ系材料から構成される磁石粉末であって、主相の平均結晶粒径が１μｍ以下であり、Ｘ線回折法で測定したＳｍ２Ｆｅ１７（３０３）ピークに対するＦｅ（１１０）ピークの強度比が０．０１〜０．８０であることを特徴とする磁石粉末が提供される。 According to a first aspect of the present invention, there is provided a magnetic powder composed of Sm-Fe-N based material, an average grain size of the main phase does not exceed 1μm or less, Sm 2 measured by X-ray diffractometry A magnet powder is provided in which the intensity ratio of the Fe (110) peak to the Fe 17 (303) peak is 0.01 to 0.80.
また、本発明の第２の要旨によれば、上記の磁石粉末の製造方法であって、サマリウムおよび鉄から構成される原料粉末を水素雰囲気下で加熱し、続いて、減圧下で加熱し、ついで、窒化することを含む製造方法が提供される。 According to a second aspect of the present invention, there is provided a method for producing the above-mentioned magnet powder, wherein the raw material powder composed of samarium and iron is heated under a hydrogen atmosphere, and subsequently heated under reduced pressure, Then, a manufacturing method including nitriding is provided.
本発明によれば、主相の平均結晶粒径を１μｍ以下とし、Ｘ線回折法で測定したＳｍ２Ｆｅ１７（３０３）ピークに対するＦｅ（１１０）ピークの強度比を０．０１〜０．８０とすることにより、粉末粒径が比較的大きくても高い保磁力を有し得るＳｍ−Ｆｅ−Ｎ系材料から構成される磁石粉末が提供される。 According to the present invention, the average crystal grain size of the main phase is 1 μm or less, and the intensity ratio of the Fe (110) peak to the Sm 2 Fe 17 (303) peak measured by the X-ray diffraction method is 0.01 to 0.80. Thus, a magnetic powder composed of an Sm—Fe—N-based material that can have a high coercive force even when the powder particle size is relatively large is provided.
本発明の磁石粉末は、Ｓｍ−Ｆｅ−Ｎ系材料から構成され、主相（結晶粒）と粒界層とを含む微細組織構造を有し、その主相の平均結晶粒径が１μｍ以下、好ましくは４００ｎｍ以下であり、Ｘ線回折法で測定したＳｍ２Ｆｅ１７（３０３）ピークに対するＦｅ（１１０）ピークの強度比が０．０１〜１．００、好ましくは０．０１〜０．８０であることを特徴とする。本発明の磁石粉末は、上記範囲の平均結晶粒径およびＳｍ２Ｆｅ１７（３０３）ピークに対するＦｅ（１１０）ピークの強度比を有することにより、非常に高い保磁力を有する。 The magnet powder of the present invention is composed of an Sm—Fe—N-based material, has a fine structure including a main phase (crystal grains) and a grain boundary layer, and an average crystal grain size of the main phase is 1 μm or less, The intensity ratio of Fe (110) peak to Sm 2 Fe 17 (303) peak measured by X-ray diffraction method is preferably 0.01 to 1.00, preferably 0.01 to 0.80. It is characterized by being. The magnet powder of the present invention has a very high coercive force by having an average crystal grain size in the above range and an intensity ratio of the Fe (110) peak to the Sm 2 Fe 17 (303) peak.
ここで主相とは、磁石粉末を構成する相の中で最も存在比率が高い相を意味し、本発明の磁石粉末においては、Ｓｍ２Ｆｅ１７Ｎｘ（ｘは２〜４である）相である。また、粒界層は、主相の間に存在する層を意味し、Ｆｅ相を含み得る。 Here, the main phase means a phase having the highest abundance ratio among phases constituting the magnet powder. In the magnet powder of the present invention, the Sm 2 Fe 17 N x (x is 2 to 4) phase. It is. Moreover, a grain boundary layer means the layer which exists between main phases, and may contain Fe phase.
上記平均結晶粒径は、例えば、走査型透過電子顕微鏡（ＴＥＭ）により磁石粉末の断面像（以下、ＴＥＭ像ともいう）を取得し、インターセプト法にて、具体的にはＴＥＭ像に縦横それぞれ複数本、例えば１０本の直線を任意に引き、それぞれの直線上にある結晶粒子の数を数え、直線の長さを結晶粒子の数で割り、２０本での平均値を計算することにより求めることができる。 The average crystal grain size is obtained by, for example, obtaining a cross-sectional image (hereinafter also referred to as a TEM image) of a magnet powder with a scanning transmission electron microscope (TEM), and using an intercept method, specifically, a plurality of vertical and horizontal TEM images. This is obtained by arbitrarily drawing 10 lines, for example, 10 lines, counting the number of crystal grains on each line, dividing the length of the line by the number of crystal grains, and calculating the average value of 20 lines. Can do.
上記Ｓｍ２Ｆｅ１７（３０３）ピークに対するＦｅ（１１０）ピークの強度比は、Ｘ線回折装置を用いて、母集団より複数、例えば３回サンプリングしそれぞれのピークを測定し、その強度比を求め、３回の平均値を計算することにより求めることができる。 The intensity ratio of the Fe (110) peak with respect to the Sm 2 Fe 17 (303) peak is obtained by sampling a plurality of, for example, three times from the population using an X-ray diffractometer and measuring each peak to obtain the intensity ratio. It can be obtained by calculating an average value of three times.
一の態様において、本発明の磁石粉末は、乾式レーザー回折法で測定した粉末の平均粒径が１０〜３００μｍ、好ましくは１０〜５０μｍ、より好ましくは２０〜４０μｍであってもよい。このような平均粒径とすることにより、高い保磁力が得られ、ボンド磁石に適用する場合の樹脂への充填性が向上する。 In one aspect, the magnet powder of the present invention may have an average particle size of 10 to 300 μm, preferably 10 to 50 μm, more preferably 20 to 40 μm, as measured by dry laser diffraction. By setting it as such an average particle diameter, a high coercive force is obtained and the filling property to resin when applying to a bond magnet improves.
本明細書において平均粒径とは、平均粒径Ｄ５０（体積基準の累積百分率５０％相当粒径）を意味する。かかる平均粒径Ｄ５０は、例えばレーザー回折式粒度分布測定装置（堀場製作所製、ＬＡ−９５０）により測定することができる。 In this specification, the average particle size means an average particle size D50 (particle size equivalent to a volume-based cumulative percentage of 50%). The average particle diameter D50 can be measured by, for example, a laser diffraction particle size distribution measuring device (LA-950, manufactured by Horiba, Ltd.).
一の態様において、本発明の磁石粉末は、透過型電子顕微鏡（ＴＥＭ）のエネルギー分散型Ｘ線（ＥＤＸ）スポット分析で測定した主相のＳｍピークに対する粒界層のＳｍピークの強度比が、０．７〜１．０であってもよい。 In one embodiment, the magnet powder of the present invention has an intensity ratio of the Sm peak of the grain boundary layer to the Sm peak of the main phase measured by energy dispersive X-ray (EDX) spot analysis of a transmission electron microscope (TEM), It may be 0.7 to 1.0.
上記のＥＤＸスポット分析のスポット径は、粒界層の厚みと同等、具体的には１〜３０ｎｍ、例えば１０ｎｍである。主相と粒界層との境界は、ＴＥＭの電子線回折分析により決定することができる。 The spot diameter of the above EDX spot analysis is equal to the thickness of the grain boundary layer, specifically 1 to 30 nm, for example, 10 nm. The boundary between the main phase and the grain boundary layer can be determined by TEM electron diffraction analysis.
本発明の磁石粉末は、Ｓｍ：Ｆｅ：Ｎの割合（ａｔ％）が、９〜１１：７６〜８１：１１〜１４であることが好ましい。Ｓｍ：Ｆｅ：Ｎ原子比をかかる範囲とすることにより高い保磁力を得ることができる。上記の割合は、蛍光Ｘ線分析により求めることができる。 The magnet powder of the present invention preferably has a Sm: Fe: N ratio (at%) of 9 to 11:76 to 81:11 to 14. By setting the Sm: Fe: N atomic ratio within such a range, a high coercive force can be obtained. The above ratio can be obtained by fluorescent X-ray analysis.
本発明の磁石粉末は、４００ｋＡ／ｍ以上の保磁力を有し得る。 The magnet powder of the present invention can have a coercive force of 400 kA / m or more.
本発明の磁石粉末は、以下のように製造することができる。 The magnet powder of the present invention can be produced as follows.
（１）原料磁石粉末の調製
まず、原料金属のサマリウムおよび鉄を配合する。サマリウムと鉄の配合割合は、特に限定されないが、例えば、サマリウムが１０〜２０原子％、好ましくは１３〜１５原子％であり、その残部が鉄である。
(1) Preparation of raw material magnetic powder First, raw material metals samarium and iron are blended. Although the blending ratio of samarium and iron is not particularly limited, for example, samarium is 10 to 20 atomic%, preferably 13 to 15 atomic%, and the remainder is iron.
上記の割合で配合したサマリウムと鉄の混合物を、例えば溶解鋳造して母材を得、これを粉砕して、Ｓｍ−Ｆｅ系の原料磁石粉末を得る。 A mixture of samarium and iron blended in the above proportion is, for example, melt-cast to obtain a base material, which is pulverized to obtain an Sm—Fe-based raw magnet powder.
上記の溶解鋳造は、特に限定されないが、好ましくは不活性ガス雰囲気下、例えばアルゴン雰囲気下で超音波溶融により行われる。得られた母材の組織を均質化するために、さらに母材を熱処理することが好ましい。かかる熱処理は、好ましくは不活性ガス雰囲気下、例えばアルゴン雰囲気下、１０００〜１２００℃、例えば１１００℃で、２４〜９６時間、例えば５０時間行われる。 The melt casting is not particularly limited, but is preferably performed by ultrasonic melting in an inert gas atmosphere, for example, an argon atmosphere. In order to homogenize the structure of the obtained base material, it is preferable to further heat-treat the base material. Such heat treatment is preferably performed in an inert gas atmosphere, for example, in an argon atmosphere, at 1000 to 1200 ° C., for example, 1100 ° C., for 24 to 96 hours, for example, 50 hours.
母材の粉砕は、自体公知の方法により行うことができる。例えば、クラッシャー、スタンプミル、ボールミル等により粉砕することができる。 The base material can be pulverized by a method known per se. For example, it can be pulverized by a crusher, a stamp mill, a ball mill or the like.
上記粉砕は、好ましくは、低酸素濃度、例えば酸素濃度１００ｐｐｍ以下、好ましくは１０ｐｐｍ以下の不活性ガス雰囲気下、例えばアルゴン雰囲気下で行われる。 The pulverization is preferably performed in an inert gas atmosphere having a low oxygen concentration, for example, an oxygen concentration of 100 ppm or less, preferably 10 ppm or less, for example, an argon atmosphere.
ついで、得られた原料磁石粉末を、徐酸化させる。徐酸化は、例えば不活性ガス雰囲気下に原料磁石粉末を置き、不活性ガスを徐々に酸素と置換することにより行うことができる。 Next, the obtained raw magnet powder is gradually oxidized. The gradual oxidation can be performed, for example, by placing the raw magnet powder in an inert gas atmosphere and gradually replacing the inert gas with oxygen.
上記のように処理された原料磁石粉末は、Ｓｍ−Ｆｅ二元系合金であり、１０〜３００μｍ、好ましくは１０〜５０μｍの平均粒径Ｄ５０（体積基準の累積百分率５０％相当粒径）を有する。この平均粒径Ｄ５０は、例えばレーザー回折式粒度分布測定装置（堀場製作所製、ＬＡ−９５０）により測定することができる。 The raw material magnetic powder treated as described above is an Sm—Fe binary alloy, and has an average particle diameter D50 (corresponding to a volume-based cumulative percentage of 50%) of 10 to 300 μm, preferably 10 to 50 μm. . This average particle diameter D50 can be measured, for example, with a laser diffraction particle size distribution measuring apparatus (LA-950, manufactured by Horiba, Ltd.).
（２）水素化・分解反応−脱水素・再結合反応（ＨＤＤＲ）処理
上記で得られた原料磁石粉末を水素雰囲気下で加熱処理することにより、原料磁石粉末に、水素化・不均化反応（ＨＤ：Hydrogenation Disproportionation）を生じさせ、Ｓｍ−Ｆｅ二元系合金をＳｍＨ２相とＦｅ相に分解する（以下、当該加熱処理を「ＨＤ処理」とも称する）。
(2) Hydrogenation / decomposition reaction-dehydrogenation / recombination reaction (HDDR) treatment The raw material magnet powder obtained above is heat-treated in a hydrogen atmosphere to produce a hydrogenation / disproportionation reaction. (HD: Hydrogenation Disproportionation) is generated, and the Sm—Fe binary alloy is decomposed into an SmH 2 phase and an Fe phase (hereinafter, the heat treatment is also referred to as “HD treatment”).
上記のＨＤ処理において、水素の分圧は、５０〜５００ｋＰａ、好ましくは１００〜２００ｋＰａである。 In the HD treatment described above, the hydrogen partial pressure is 50 to 500 kPa, preferably 100 to 200 kPa.
上記のＨＤ処理において、加熱温度は、７００〜９００℃、好ましくは８００℃である。 In the above HD treatment, the heating temperature is 700 to 900 ° C., preferably 800 ° C.
上記のＨＤ処理において、加熱時間は、１０分〜３００分、好ましくは３０〜１２０分である。 In the above HD treatment, the heating time is 10 minutes to 300 minutes, preferably 30 minutes to 120 minutes.
上記のＨＤ処理に続いて、減圧下で原料磁石粉末を加熱処理することにより水素を排出して、原料磁石粉末に、脱水素・再結合反応（ＤＲ：Desorption Recombination）を生じさせ、Ｓｍ−Ｆｅ二元系合金を再形成する（以下、当該加熱処理を「ＤＲ処理」とも称する）。 Subsequent to the HD treatment described above, the raw magnet powder is heat-treated under reduced pressure to discharge hydrogen to cause dehydrogenation and recombination (DR) in the raw magnet powder. The binary alloy is reformed (hereinafter, the heat treatment is also referred to as “DR treatment”).
上記のＤＲ処理において、「減圧下」とは、５０Ｐａ以下、好ましくは１０Ｐａ以下の圧力であることを意味する。 In the above-described DR treatment, “under reduced pressure” means a pressure of 50 Pa or less, preferably 10 Pa or less.
上記のＤＲ処理において、加熱温度は、７００〜９００℃、好ましくは７６０〜８４０℃である。当該加熱温度により、脱水素・再結合反応の速度を調節することができる。 In the DR treatment, the heating temperature is 700 to 900 ° C, preferably 760 to 840 ° C. The rate of dehydrogenation / recombination reaction can be adjusted by the heating temperature.
上記のＤＲ処理において、加熱時間は、１０分〜３００分、好ましくは３０〜１２０分である。 In the DR treatment, the heating time is 10 minutes to 300 minutes, preferably 30 to 120 minutes.
上記の水素化・分解反応、脱水素・再結合反応の一連の処理方法を、ＨＤＤＲ法という。かかるＨＤＤＲ法により、原料磁石粉末を処理することにより、微細な結晶を得ることができ、高い保磁力が達成できる。 A series of treatment methods of the above hydrogenation / decomposition reaction and dehydrogenation / recombination reaction is called HDDR method. By processing the raw magnet powder by the HDDR method, fine crystals can be obtained and high coercive force can be achieved.
（３）窒化処理
上記のように処理された原料磁石粉末を、窒素雰囲気下で熱処理することにより、結晶内に窒素が取り込まれ（窒化）、本発明のＳｍ−Ｆｅ−Ｎ系材料から構成される磁石粉末が得られる。
(3) Nitriding treatment The raw material magnetic powder treated as described above is heat-treated in a nitrogen atmosphere, so that nitrogen is taken into the crystal (nitriding) and is composed of the Sm—Fe—N-based material of the present invention. Magnet powder is obtained.
上記の窒化処理において、窒素の分圧は、５０〜５００ｋＰａ、好ましくは１００〜２００ｋＰａである。 In the above nitriding treatment, the partial pressure of nitrogen is 50 to 500 kPa, preferably 100 to 200 kPa.
上記の窒化処理において、加熱温度は、３００〜６００℃、好ましくは４００〜５００℃である。 In said nitriding process, heating temperature is 300-600 degreeC, Preferably it is 400-500 degreeC.
上記の窒化処理において、加熱時間は、１〜７２時間、好ましくは１２〜４８時間である。この加熱時間を調節することにより、磁石粉末に取り込まれる窒素の量を調節することができる。 In the above nitriding treatment, the heating time is 1 to 72 hours, preferably 12 to 48 hours. By adjusting the heating time, the amount of nitrogen taken into the magnet powder can be adjusted.
上記（１）〜（３）の処理を含む方法により得られた本発明の磁石粉末は、磁石粉末の粒径を１０μｍ未満にしなくても、非常に高い保磁力を有する。このような磁石粉末は、樹脂への充填性が高いので、ボンド磁石に好適に適用される。 The magnet powder of the present invention obtained by the method including the treatments (1) to (3) has a very high coercive force even if the particle size of the magnet powder is not less than 10 μm. Such a magnet powder is suitable for bonded magnets because of its high filling ability into the resin.
すなわち、本発明は、サマリウムおよび鉄から構成される原料粉末を水素雰囲気下で加熱し、ついで、真空中で加熱することを含むＳｍ−Ｆｅ−Ｎ系材料から構成される磁石粉末の製造方法をも提供する。 That is, the present invention provides a method for producing a magnet powder composed of an Sm—Fe—N-based material, which includes heating a raw material powder composed of samarium and iron in a hydrogen atmosphere and then heating in a vacuum. Also provide.
（実施例）
・実施例１〜７および比較例１〜７
原料金属のサマリウムおよび鉄を、表１に示す組成になるように秤量し、これを高周波溶解炉にてアルゴン雰囲気下で溶解鋳造し、母合金３０ｇを作製した。これをアルゴンガス中、５０時間１１００℃で熱処理し、母合金の組織を均質化した。均質化した母合金を、酸素濃度１０ｐｐｍ以下のアルゴン雰囲気下で、クラッシャー、スタンプミル、ボールミルの順に粉砕を施し、目開き４０μｍの篩いを通過させて原料粉末を得た。
(Example)
-Examples 1-7 and Comparative Examples 1-7
Raw metal samarium and iron were weighed so as to have the composition shown in Table 1, and melted and cast in an argon atmosphere in a high frequency melting furnace to produce 30 g of a master alloy. This was heat-treated in argon gas at 1100 ° C. for 50 hours to homogenize the structure of the master alloy. The homogenized master alloy was pulverized in the order of a crusher, a stamp mill, and a ball mill in an argon atmosphere with an oxygen concentration of 10 ppm or less, and passed through a sieve having an opening of 40 μm to obtain a raw material powder.
次に、アルゴンと酸素を徐々に置換し、原料粉末を徐酸化させた。蛍光Ｘ線分析装置（ＸＲＦ）（堀場製作所製：ＭＥＳＡ５０；線源：ＲｈＫα）で定量分析した組成を表１に併せて示す（Ｓｍ−Ｆｅ二元系合金換算）。 Next, argon and oxygen were gradually replaced to gradually oxidize the raw material powder. The composition quantitatively analyzed with a fluorescent X-ray analyzer (XRF) (manufactured by Horiba: MESA50; radiation source: RhKα) is also shown in Table 1 (in terms of Sm-Fe binary alloy).
徐酸化した原料粉末をアルミナるつぼに入れ、１０１ｋＰａの水素雰囲気下８００℃で、６０分間熱処理した（水素化・分解（ＨＤ）処理）。続いて、真空ポンプで水素を排出し、減圧下（５Ｐａ）、表１に示す温度で、３０分間加熱処理した（脱水素・再結合（ＤＲ）処理）。加熱処理した原料粉末を１０１ｋＰａの窒素雰囲気下４７０℃で、２４時間熱処理して窒化させて、Ｓｍ−Ｆｅ−Ｎ系材料から構成される磁石粉末を得た。 The gradually oxidized raw material powder was placed in an alumina crucible and heat-treated at 800 ° C. for 60 minutes in a 101 kPa hydrogen atmosphere (hydrogenation / decomposition (HD) treatment). Subsequently, hydrogen was discharged with a vacuum pump, and heat treatment was performed at a temperature shown in Table 1 under reduced pressure (5 Pa) for 30 minutes (dehydrogenation / recombination (DR) treatment). The heat-treated raw material powder was heat treated and nitrided at 470 ° C. for 24 hours under a nitrogen atmosphere of 101 kPa to obtain a magnet powder composed of an Sm—Fe—N-based material.
・比較例８
原料金属のサマリウムおよび鉄を、表１に示す組成になるように秤量し、これを高周波溶解炉にてアルゴン雰囲気下で溶解鋳造し、母合金３０ｇを作製した。これをアルゴンガス中、５０時間１１００℃で熱処理し、母合金の組織を均質化した。均質化した母合金を、酸素濃度１０ｐｐｍ以下のアルゴン雰囲気下で、クラッシャー、スタンプミル、ボールミルの順に粉砕を施し、目開き４０μｍの篩いを通過させて原料粉末を得た。
Comparative Example 8
Raw metal samarium and iron were weighed so as to have the composition shown in Table 1, and melted and cast in an argon atmosphere in a high frequency melting furnace to produce 30 g of a master alloy. This was heat-treated in argon gas at 1100 ° C. for 50 hours to homogenize the structure of the master alloy. The homogenized master alloy was pulverized in the order of a crusher, a stamp mill, and a ball mill in an argon atmosphere with an oxygen concentration of 10 ppm or less, and passed through a sieve having an opening of 40 μm to obtain a raw material powder.
次に、アルゴンと酸素を徐々に置換し、原料粉末を徐酸化させた。蛍光Ｘ線分析装置（ＸＲＦ）（堀場製作所製：ＭＥＳＡ５０；線源：ＣｕＫα）で定量分析した組成は、Ｓｍ−Ｆｅ二元系合金換算でサマリウムが１１．８原子％、鉄が残部だった。 Next, argon and oxygen were gradually replaced to gradually oxidize the raw material powder. The composition quantitatively analyzed with a fluorescent X-ray analyzer (XRF) (manufactured by Horiba: MESA50; radiation source: CuKα) was 11.8 atomic% of samarium and iron was the balance in terms of Sm-Fe binary alloy.
徐酸化した原料粉末をアルミナるつぼに入れ、１０１ｋＰａの窒素雰囲気下４７０℃で、２４時間熱処理して窒化させて、比較例８の磁石粉末を得た。 The gradually oxidized raw material powder was put in an alumina crucible and subjected to nitriding by heat treatment at 470 ° C. for 24 hours under a 101 kPa nitrogen atmosphere to obtain a magnet powder of Comparative Example 8.
（評価）
・平均粒径
上記で得られた実施例１〜７および比較例１〜８の磁石粉末の各々について、平均粒径Ｄ５０を、レーザー回折式粒度分布測定装置（堀場製作所製、ＬＡ−９５０）で測定した。結果を表１に併せて示す。
(Evaluation)
-Average particle diameter About each of the magnetic powder of Examples 1-7 obtained above and Comparative Examples 1-8, average particle diameter D50 was measured with the laser diffraction type particle size distribution measuring apparatus (the Horiba make, LA-950). It was measured. The results are also shown in Table 1.
・走査型透過電子顕微鏡（ＴＥＭ）解析
上記で得られた実施例１の磁石粉末について、粉体をイオンミリングすることにより粉体を薄く加工し、走査型透過電子顕微鏡（ＴＥＭ）（日立ハイテクノロジーズ社製、ＨＤ−２３００Ａ）で断面像を撮影した。得られた画像を、図１に示す。
Scanning Transmission Electron Microscope (TEM) Analysis The magnet powder of Example 1 obtained above was thinly processed by ion milling the powder, and the scanning transmission electron microscope (TEM) (Hitachi High Technologies) A cross-sectional image was taken with HD-2300A). The obtained image is shown in FIG.
図１から明らかなように、得られた粉体は微細な結晶粒の主相から構成され、さらに結晶粒界にはより微細な（平均結晶粒径が約３ｎｍ）微結晶体が存在することが確認された。主相の結晶粒および結晶粒界に存在する微結晶体について、ＴＥＭを用いて電子回折図形を撮影し、得られた回折パターンの位置から、主相がＳｍ２Ｆｅ１７Ｎｘ（ｘは、２〜４である）相であり、微結晶体がα−Ｆｅ相であることが確認された。 As is apparent from FIG. 1, the obtained powder is composed of a main phase of fine crystal grains, and there are finer crystals (average crystal grain size is about 3 nm) at the crystal grain boundaries. Was confirmed. An electron diffraction pattern was photographed using TEM for the crystal grains of the main phase and the crystallites present at the crystal grain boundaries. From the position of the obtained diffraction pattern, the main phase was Sm 2 Fe 17 N x (x is It was confirmed that the microcrystalline body was an α-Fe phase.
実施例１〜７および比較例１〜８の磁石粉末の各々について、ＳｍおよびＦｅの含有量を蛍光Ｘ線分析装置（ＸＲＦ）（堀場製作所製：ＭＥＳＡ５０；線源：ＣｕＫα）の定量分析により測定し、Ｎの含有量を、酸素・窒素分析装置（堀場製作所製：ＥＭＧＡ−９２０）で測定した。得られた値から、Ｓｍ−Ｆｅ−Ｎの三成分の合計１００原子％に対する各原子の割合（原子％）を求めた。結果を表１に併せて示す。 For each of the magnetic powders of Examples 1 to 7 and Comparative Examples 1 to 8, the Sm and Fe contents were measured by quantitative analysis using a fluorescent X-ray analyzer (XRF) (Horiba Seisakusho: MESA50; radiation source: CuKα). The N content was measured with an oxygen / nitrogen analyzer (Horiba, Ltd .: EMGA-920). From the obtained value, the ratio (atomic%) of each atom to the total of 100 atomic% of the three components of Sm—Fe—N was determined. The results are also shown in Table 1.
・平均結晶粒径
実施例１〜７および比較例１〜８の磁石粉末の各々について、上記と同様に倍率が５００００倍のＴＥＭ像を撮り、このＴＥＭ像からインターセプト法にて結晶粒径を求めた。すなわち、ＴＥＭ像に縦横それぞれ１０本の直線を任意に引き、それぞれの直線上にある結晶粒子の数を数え、直線の長さを結晶粒子の数で割り、２０本の平均を求めて、これを平均結晶粒径とした。結果を表１に併せて示す。
-Average crystal grain size For each of the magnet powders of Examples 1 to 7 and Comparative Examples 1 to 8, a TEM image with a magnification of 50000 times was taken in the same manner as described above, and the crystal grain size was obtained from this TEM image by the intercept method. It was. That is, arbitrarily draw 10 straight lines in the vertical and horizontal directions on the TEM image, count the number of crystal grains on each straight line, divide the length of the straight line by the number of crystal grains, and obtain the average of 20 lines. Was the average crystal grain size. The results are also shown in Table 1.
・Ｘ線回折（ＸＲＤ）ピーク強度比
実施例１〜７および比較例１〜８の磁石粉末の各々について、Ｘ線回折装置（リガク社製；ＭｉｎｉｆｌｅｘＩＩ Ｃｕ管球仕様）、およびＸ線検出装置（リガク社製；Ｄ／ｔｅＸ Ｕｌｔｒａ）を用いて、ステップ幅０．０５°、ステップ時間３秒として磁石粉末の回折強度を測定し、Ｓｍ２Ｆｅ１７相の（３０３）面のピーク高さに対するα−Ｆｅの（１１０）面のピーク高さの比を求め、３か所で測定を行いそれらの平均値を求め、これをＸＲＤピーク強度比とした。結果を表１に併せて示す。
X-ray diffraction (XRD) peak intensity ratio For each of the magnetic powders of Examples 1 to 7 and Comparative Examples 1 to 8, an X-ray diffraction device (manufactured by Rigaku Corporation; Miniflex II Cu tube specification) and an X-ray detection device ( Using D / teX Ultra), the diffraction intensity of the magnet powder was measured with a step width of 0.05 ° and a step time of 3 seconds, and α relative to the peak height of the (303) plane of the Sm 2 Fe 17 phase. The ratio of the peak height of the (110) plane of -Fe was determined, and measurement was performed at three locations to determine the average value thereof, which was taken as the XRD peak intensity ratio. The results are also shown in Table 1.
・エネルギー分散型Ｘ線（ＥＤＸ）ピーク強度比
実施例１〜７および比較例１〜８の磁石粉末の各々について、上記のＴＥＭを用いて、Ｓｍ２Ｆｅ１７Ｎｘ主相および粒界層部分に、粒界層の厚みと同等（例えば３ｎｍ）のビーム径の電子線を照射し、エネルギー分散型Ｘ線スポット分析を行った。蛍光Ｘ線エネルギーが５．６ｋｅＶのＳｍピークについて、Ｓｍ２Ｆｅ１７Ｎｘ主相のピークに対する粒界層のピークの強度比を計算して、これをＥＤＸピーク強度比とした。結果を表１に併せて示す。
Energy dispersive X-ray (EDX) peak intensity ratio For each of the magnetic powders of Examples 1 to 7 and Comparative Examples 1 to 8, using the above TEM, Sm 2 Fe 17 N x main phase and grain boundary layer part The sample was irradiated with an electron beam having a beam diameter equivalent to the thickness of the grain boundary layer (for example, 3 nm), and energy dispersive X-ray spot analysis was performed. For the Sm peak having a fluorescent X-ray energy of 5.6 keV, the intensity ratio of the grain boundary layer peak to the peak of the Sm 2 Fe 17 N x main phase was calculated, and this was used as the EDX peak intensity ratio. The results are also shown in Table 1.
・保磁力
実施例１〜７および比較例１〜８の磁石粉末の各々について、内容積０．０７ｃｍ３の容器に磁性粉末を充填し、Ｂ−Ｈトレーサー（日本電磁測器製）にて最大磁界５５ｋＯｅを印加して保磁力の測定を行った。結果を表１に併せて示す。
-Coercive force For each of the magnet powders of Examples 1 to 7 and Comparative Examples 1 to 8, magnetic powder was filled in a container having an internal volume of 0.07 cm 3 , and maximum was obtained with a BH tracer (manufactured by Nippon Electron Sokki). A coercive force was measured by applying a magnetic field of 55 kOe. The results are also shown in Table 1.
表１から明らかなように、Ｘ線回折法で測定したＳｍ２Ｆｅ１７（３０３）ピークに対するＦｅ（１１０）ピークの強度比が１．００以下である実施例１〜７は、平均結晶粒径は同程度であるが上記強度比が１．００より大きい比較例１〜７と比較して、高い保磁力を有することが確認された。また、主相の平均結晶粒径が１μｍ以下である実施例１〜７は、上記強度比は１．００以下であるが平均結晶粒径が２６μｍである比較例８と比較して、高い保磁力（ＨｃＪ：固有保磁力）を有することが確認された。 As is clear from Table 1, Examples 1 to 7 in which the intensity ratio of the Fe (110) peak to the Sm 2 Fe 17 (303) peak measured by X-ray diffraction method is 1.00 or less are average crystal grain sizes. However, it was confirmed that it has a high coercive force as compared with Comparative Examples 1 to 7 in which the intensity ratio is larger than 1.00. In addition, Examples 1 to 7 in which the average crystal grain size of the main phase is 1 μm or less are higher than those in Comparative Example 8 in which the above-mentioned strength ratio is 1.00 or less but the average crystal grain size is 26 μm. It was confirmed to have a magnetic force (HcJ: intrinsic coercive force).
本発明の磁石粉末は、ボンド磁石やモーター用磁石など、幅広く様々な用途に使用され得る。 The magnet powder of the present invention can be used in a wide variety of applications such as bonded magnets and motor magnets.
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