【発明の詳細な説明】[Detailed description of the invention]
本発明は磁性材料用Fe−Co−Mn−Ｃ合金に関
する。
現在各方面で用いられているFe−Cr−Co系合
金は冷間加工、例えば圧延、伸線およびスエージ
加工等が容易であるという特徴を有する永久磁石
として知られている。そしてさらに磁性特性を向
上させるための努力が払われている。ところで、
Fe−Cr−Co系合金は永久磁石としての特性を得
るために強い磁性の相と弱い磁性の相を適当に分
散させる熱処理方法が用いられている。しかしな
がら、その熱処理方法は特定の温度範囲を所定の
ゆつくりした速度（例えば、20℃／時間）で降下
させ、さらに長時間の時効処理を施すものであ
り、10時間あるいはそれ以上の熱処理時間を必要
とする方法である。さらに上記降温速度が磁性特
性に大きく影響を与えるため、降温プログラムは
厳密に管理することが必要である。その問題点を
解決するために、連続降温でなく、10℃〜20℃の
間隔で段階的に降温させる方法が提案されている
が、やはり長時間の熱処理が必要である。
本発明は、Fe−Cr−Co係合金におけるような
熱処理に必要な厳密な降温プログラムの管理や長
時間の熱処理を必要とせず、１時間程度の短時間
の熱処理で所望の磁性特性が得られ、さらに所望
の場所を非磁性化できるという大きな特徴を有す
る磁性材料用合金を提供するものである。
本発明の磁性材料用合金はCoが30〜55重量
％、Mnが15〜27重量％およびＣが0.3〜2.0重量
％、そして残部が、Feからなることを特徴とす
る合金である。Feは910℃〜1390℃の温度範囲で
非磁性の面心立方構造（以下、γ相という）とな
るが、室温に急冷すると、強磁性の体心立方構造
（以下、α相という）となる。FeにMnを添加
し、Mnの添加量を増加すると、γ／（γ＋α）
境界が低温側へ向つて移り、そして、Ｃを少量添
加すると、高温での非磁性のγ相が室温で得られ
る。以上のようなFe Mn Ｃ合金を強度に冷間加
工し、低温で熱処理してγ相を強磁性相に変態さ
せると、Mnが少量では高い保磁力（以下、Hcと
いう）が得られず、Mnが多量になると磁化量が
減少する。さらにCoの添加は、強磁性相の磁化
量を増加させる効果がある。
上記の本発明の合金は、熱平衡状態で非磁性の
γ相が得られる温度範囲で熱処理した後、室温に
急冷すると相変態が起ることなくγ相状態であ
り、冷間圧延、冷間スエージおよび冷間伸線加工
を強度に施しても割れを生じることはなく、しか
も非磁性状態を保持し、良好な加工性を有する合
金であることがわかつた。これらの冷間加工を行
なつた後、従来の合金に比べ非常に短時間で、簡
単な熱処理によつて所望の磁気特性が得られるこ
とが本発明の合金の大きな特徴である。
次に本発明の合金について実施例によつて説明
する。まず試料として次の第１表に示すNo.1〜
11の11種類の組成を選んだ。また比較のため
No.12として公知のFe−Cr−Co−Ti合金を選ん
だ。
The present invention relates to a Fe-Co-Mn-C alloy for magnetic materials. Fe-Cr-Co alloys, which are currently used in various fields, are known as permanent magnets that are easy to cold-work, such as rolling, wire drawing, and swaging. Efforts are being made to further improve the magnetic properties. by the way,
In order to obtain properties as a permanent magnet for Fe-Cr-Co alloys, a heat treatment method is used to appropriately disperse a strong magnetic phase and a weak magnetic phase. However, this heat treatment method involves lowering a specific temperature range at a predetermined slow rate (for example, 20°C/hour) and then subjecting it to an aging treatment for a long time, and the heat treatment time is 10 hours or more. This is the method you need. Furthermore, since the rate of temperature reduction greatly affects the magnetic properties, it is necessary to strictly control the temperature reduction program. In order to solve this problem, a method has been proposed in which the temperature is lowered stepwise at intervals of 10°C to 20°C instead of continuously, but this method still requires a long heat treatment. The present invention does not require strict temperature-lowering program management or long-term heat treatment that is required for heat treatment as in the case of Fe-Cr-Co alloys, and the desired magnetic properties can be obtained with a short heat treatment of about one hour. Furthermore, the present invention provides an alloy for magnetic materials which has the great feature of being able to make desired locations non-magnetic. The alloy for magnetic materials of the present invention is characterized by comprising 30 to 55% by weight of Co, 15 to 27% by weight of Mn, 0.3 to 2.0% by weight of C, and the balance consisting of Fe. Fe has a non-magnetic face-centered cubic structure (hereinafter referred to as γ phase) in the temperature range of 910℃ to 1390℃, but when rapidly cooled to room temperature, it changes to a ferromagnetic body-centered cubic structure (hereinafter referred to as α phase). . When Mn is added to Fe and the amount of Mn added is increased, γ/(γ+α)
If the boundary is shifted towards the low temperature side and a small amount of C is added, a high temperature non-magnetic γ phase is obtained at room temperature. When the Fe Mn C alloy described above is cold worked to a high strength and heat treated at low temperature to transform the γ phase into a ferromagnetic phase, a high coercive force (hereinafter referred to as Hc) cannot be obtained with a small amount of Mn. When the amount of Mn increases, the amount of magnetization decreases. Furthermore, the addition of Co has the effect of increasing the amount of magnetization of the ferromagnetic phase. The above-mentioned alloy of the present invention is heat treated in a temperature range in which a non-magnetic γ phase is obtained in a thermal equilibrium state, and then rapidly cooled to room temperature to maintain a γ phase state without phase transformation. It was also found that the alloy does not crack even when subjected to intense cold wire drawing, maintains a non-magnetic state, and has good workability. A major feature of the alloy of the present invention is that, after cold working, desired magnetic properties can be obtained through simple heat treatment in a much shorter time than with conventional alloys. Next, the alloy of the present invention will be explained using examples. First, as a sample, No.1~ shown in Table 1 below.
We selected 11 different compositions. Also for comparison
A Fe-Cr-Co-Ti alloy known as No. 12 was selected.
【表】
まず、第１表のNo.1〜６に示した化学成分組
成の合金インゴツトは1100℃の温度で１時間、
Ar雰囲気中で溶体化処理した後、10％NaOH水溶
液中に浸して急冷した、これらの合金インゴツト
から各々小片を切り出し、磁化量を測定すると、
飽和磁束密度（以下、Bsという）はいずれも
10Gauss程度であつた。また、Ｘ線回折により結
晶構造を調べたところ、いずれも面心立方構造以
外の回折パターンは観測されず、γ相が室温で得
られたことを確認した。No.7〜11は本発明の特
許請求の範囲から外れた化学成分組成の合金イン
ゴツトであるが、No.1〜６の合金インゴツトと
同様の処理を施したところ、No.7〜10は同様の
結果が得られた。しかし、No.11の合金インゴツ
トは、Bs＝14.5KGaussとなり、非磁性のγ相を
室温に導入できなかつた。No.1〜10のγ相状態
の合金インゴツトの表面酸化膜を除去した後、冷
間伸線、冷間スエージあるいは冷間圧延加工を施
し、その後、Ar雰囲気中で熱処理を施した。ま
た第１表のNo.12はFe−Cr−Co系合金の１例で
ある。No.12の合金インゴツトは、1180℃で１時
間水素雰囲気中で溶体化処理を施し、水中に浸し
て急冷した。その後、減面率70％の冷間伸線加工
を施し、再び、650℃で１時間水素雰囲気中で熱
処理を施し、水中に急冷した（条件Ａ）。その
後、再び、625℃から505℃まで18℃／時間の速度
で降しつつ熱処理（水素雰囲気中）し、さらに
505℃で８時間、水素雰囲気中で熱処理を施した
（条件Ｂ）。次に、第１表に示した試料の組成と各
種処理条件及び磁気特性との関係を第２表に示
す。[Table] First, alloy ingots having the chemical composition shown in Nos. 1 to 6 in Table 1 were heated at a temperature of 1100℃ for 1 hour.
After solution treatment in an Ar atmosphere, small pieces were cut from each of these alloy ingots, which were quenched by immersion in a 10% NaOH aqueous solution, and the amount of magnetization was measured.
The saturation magnetic flux density (hereinafter referred to as Bs) is
It was about 10 Gauss. Furthermore, when the crystal structure was examined by X-ray diffraction, no diffraction pattern other than a face-centered cubic structure was observed, confirming that the γ phase was obtained at room temperature. Nos. 7 to 11 are alloy ingots with chemical compositions that are outside the scope of the claims of the present invention, but when they were subjected to the same treatment as the alloy ingots of Nos. 1 to 6, Nos. 7 to 10 were the same. The results were obtained. However, in the alloy ingot No. 11, Bs=14.5 KGauss, and the nonmagnetic γ phase could not be introduced at room temperature. After removing the surface oxide film of the alloy ingots No. 1 to 10 in the γ phase state, they were subjected to cold wire drawing, cold swaging, or cold rolling, and then heat treated in an Ar atmosphere. Further, No. 12 in Table 1 is an example of an Fe-Cr-Co alloy. Alloy ingot No. 12 was subjected to solution treatment at 1180°C for 1 hour in a hydrogen atmosphere, and then quenched by immersion in water. Thereafter, it was subjected to cold wire drawing with an area reduction rate of 70%, heat treated again at 650°C for 1 hour in a hydrogen atmosphere, and rapidly cooled in water (condition A). After that, heat treatment was performed again (in a hydrogen atmosphere) from 625℃ to 505℃ while decreasing the temperature at a rate of 18℃/hour.
Heat treatment was performed at 505° C. for 8 hours in a hydrogen atmosphere (condition B). Next, Table 2 shows the relationship between the composition of the samples shown in Table 1, various processing conditions, and magnetic properties.
【表】【table】
【表】
第２表中の試料No.1〜６は本発明の請求範囲
内の組成であり、短時間で熱処理ができ、磁気諸
特性を良好な値を示している。一方、No.7〜10
は請求範囲外の組成であり磁気特性は請求範囲内
の値に比べ大きく劣つている。また公知のFe−
Cr−Co系合金は、本発明の合金と同様の60分の
熱処理ではかなり劣つた磁気特性しか得られず、
本発明の合金と同等の磁気特性を得るためには前
述の条件Ａ及び条件Ｂのような長時間の処理が必
要である。なお、本発明の合金は第２表に示した
熱処理条件に限定されることはなく温度は520℃
〜400℃、時間は180分〜３分の範囲の適当な熱処
理条件を選ぶことによつても良好な磁気特性が得
られる。
第２表の結果から、本発明の合金の組成請求範
囲を次のように限定する。Coが30重量％〜55重
量％を外れると保磁力残留磁束密度（以下Brと
云う）、Br／Bs、および最大エネルギー積（以下
BHmaxと云う）が劣化した。したがつてCoは30
重量％〜55重量％の範囲が必要である。しかし
Coが30重量％のときMnを27重量％より多く加え
る磁化量が減少し、実用的でなくなり、、Coが55
重量％のときはMnを15重量％を下まわつて添加
すると磁気的に硬い合金は得られなかつた。した
がつて、Mnの範囲は15重量％〜27重量％とし
た。Mnを27重量％添加した本発明の合金に対し
ては、Ｃを0.3重量％を下まわつて添加するとγ
相を室温に導入することが不可能であつた。また
Ｃは2.0重量％まで本発明の合金のγ相内に固溶
させることができた。Mnを27重量％、Ｃを0.3重
量％添加した本発明の合金は強度の冷間加工を施
すことができた。したがつて、Ｃの範囲は0.3重
量％〜2.0重量％とした。
以上第２表に示すように、本発明の請求範囲内
の組成を有する合金は、Fe−Cr−Co系合金のよ
うに複雑で、長時間の熱処理を必要とせず、簡単
な熱処理を施すことで、良好な磁気特性を有する
ことがわかつた。
さらに本発明の合金では合金インゴツトを減面
率で99％の冷間伸線加工を施し得られた合金細線
を、480℃の温度に保持された均熱長200mmの水素
雰囲気の貫通炉の一方端から連続して、60mm／分
の速度で送り込み、他の一方端より連続して取り
出し、直径400mmのドラムに巻き取る熱処理方法
によつても、例えば第１表に示したNo.1の組成
ではHc＝550（Oe）、Br＝9.5（KGauss）、Sq＝
0.93、BHmax＝2.5（MGauss・Oe）の良好な磁
気特性が得られた。
さらに本発明の合金の他の大きな特徴は、熱処
理をし所望の磁気特性を得た後、得られた合金中
の所望の場所を約1000℃、１秒間程度の条件で加
熱後急冷すると、その場所が非磁性化することで
ある。
これを実施例によつて説明する。第１表の
No.1の組成について冷間スエージ加工をし440℃
−60分の熱処理によつて得られた棒状合金を長さ
方向の中心軸を軸にして１回転／秒の速度で回転
させ、5W連続発振YAGレーザの１mm直径のレー
ザビームを10秒間照射した。このレーザを照射し
た部分を切り出し磁化量を測定するとBsの値が
約10ガウスとなり、ほとんど非磁性のγ相になつ
ていることを確認した。したがつて、本発明の合
金は、レーザビーム、電子ビーム、赤外線ビーム
等を用いて所望の場所を非磁性化でき、強磁性領
域と非磁性領域の複合化が可能である。
以上本発明の合金は、強度の冷間加工が容易
で、熱処理も非常に簡単であるという特徴を有
し、さらに所望の部分を非磁性化できるという特
徴もあり、工業上、多くの分野において有用な磁
性材料である。[Table] Samples Nos. 1 to 6 in Table 2 have compositions within the claimed range of the present invention, can be heat-treated in a short time, and exhibit good values for various magnetic properties. On the other hand, No.7~10
has a composition outside the claimed range, and its magnetic properties are significantly inferior to those within the claimed range. Also known as Fe−
Cr-Co alloys obtained considerably inferior magnetic properties when subjected to the same 60-minute heat treatment as the alloys of the present invention;
In order to obtain magnetic properties equivalent to those of the alloy of the present invention, long-term treatment as described above under conditions A and B is necessary. The alloy of the present invention is not limited to the heat treatment conditions shown in Table 2; the temperature is 520°C.
Good magnetic properties can also be obtained by selecting appropriate heat treatment conditions in the range of ~400°C and 180 minutes to 3 minutes. Based on the results in Table 2, the claimed composition range of the alloy of the present invention is limited as follows. When Co is outside of 30% to 55% by weight, coercive force residual magnetic flux density (hereinafter referred to as Br), Br/Bs, and maximum energy product (hereinafter referred to as
BHmax) has deteriorated. Therefore Co is 30
A range of 55% by weight is required. but
When Co is 30% by weight, the amount of magnetization when adding more than 27% by weight of Mn decreases, making it impractical, and Co is 55% by weight.
When Mn was added in an amount less than 15% by weight, a magnetically hard alloy could not be obtained. Therefore, the range of Mn was set to 15% to 27% by weight. For the alloy of the present invention containing 27% by weight of Mn, if C is added below 0.3% by weight, γ
It was not possible to bring the phase to room temperature. Further, up to 2.0% by weight of C could be dissolved in the γ phase of the alloy of the present invention. The alloy of the present invention containing 27% by weight of Mn and 0.3% by weight of C could be subjected to strong cold working. Therefore, the range of C was set to 0.3% to 2.0% by weight. As shown in Table 2 above, alloys having compositions within the scope of the claims of the present invention are complex like Fe-Cr-Co alloys and do not require long heat treatment, but can be easily heat treated. It was found that it has good magnetic properties. Furthermore, in the alloy of the present invention, the alloy ingot is subjected to cold wire drawing with an area reduction rate of 99%, and the resulting alloy wire is placed in a through-hole furnace in a hydrogen atmosphere with a soaking length of 200 mm and maintained at a temperature of 480°C. For example, composition No. 1 shown in Table 1 can be obtained by a heat treatment method in which the material is continuously fed in from one end at a speed of 60 mm/min, taken out continuously from the other end, and wound onto a drum with a diameter of 400 mm. Then Hc=550 (Oe), Br=9.5 (KGauss), Sq=
Good magnetic properties of 0.93 and BHmax=2.5 (MGauss・Oe) were obtained. Furthermore, another major feature of the alloy of the present invention is that after heat treatment to obtain the desired magnetic properties, a desired location in the obtained alloy is heated at about 1000°C for about 1 second and then rapidly cooled. The place becomes non-magnetic. This will be explained using an example. Table 1
The composition of No. 1 was cold swaged at 440℃.
-The rod-shaped alloy obtained by heat treatment for 60 minutes was rotated at a speed of 1 revolution/second around the central axis in the longitudinal direction, and irradiated with a laser beam of 1 mm diameter from a 5W continuous wave YAG laser for 10 seconds. . When we cut out the part irradiated with this laser and measured the amount of magnetization, we found that the Bs value was approximately 10 Gauss, confirming that it was almost in the nonmagnetic γ phase. Therefore, the alloy of the present invention can be made nonmagnetic at a desired location using a laser beam, an electron beam, an infrared beam, etc., and it is possible to combine a ferromagnetic region and a nonmagnetic region. As described above, the alloy of the present invention has the characteristics that it can be easily cold-worked for strength and that it can be heat-treated very easily.It also has the characteristic that it can be made non-magnetic in desired parts, and is used in many industrial fields. It is a useful magnetic material.