【発明の詳細な説明】[Detailed description of the invention]
本発明は高透磁率が要求される磁気シールド部
材に適用して良好な磁気特性を有し、さらに磁気
特性を失うことなく熱間加工性を改善した磁性合
金に関する。
Ni−Fe系高透磁率合金を用いた磁気シールド
部材は、例えばテープレコーダ等の磁気記録装置
における磁気ヘツドのシールドケースとして広く
用いられている。なかでもMo、Cu等を含む高Ni
パーマロイ（JIS−PC材）および低Niパーマロ
イ（JIS−PB材）が多く用いられている。前者は
高透磁率、高耐食性を有するが、高価なNiを、
76重量％（以下単に％と記す）以上と、多量に含
み、さらに高価なMoをも含有しているため磁性
合金の中では価格が高いという欠点がある。また
後者はNi量が45％程度であるため、安価でかつ
100エルステツドにおける磁束密度B10が
14000Gaussと高い反面、耐食性が極端に劣ると
共に初透磁率μiが5000で前者に比べ低いという欠
点がある。例えば安価な45％Ni−Feパーマロイ
を磁気シールド用ヘツドケースとして用いるため
には、防錆処理としてメツキ処理を施す必要があ
り、工業上不利である。
故に従来のJIS−PC材およびPB材では、磁性
特性に優れ、高耐食性を有し、かつ安価な磁性合
金材料を得ることは困難である。しかしながら工
業的には磁気特性、熱間加工性および耐食性に優
れさらに安価な磁性合金を求める要望が強い。
本発明は上記の要望に対してなされたもので、
JIS−PC材の特性を損なわないで高価なMoを全
く含まず、さらに高価なNi含有量を低減した新
規な磁性合金を提供するものである。
Ni−Fe合金にCuを添加したNi−Fe−Cu合金
についての研究は古くから行なわれており、優れ
た磁気特性を有することはよく知られており（例
えばＲ・M.Bozorth著“Ferromagnetism”、D.
van Nostrand Co.1951）、Ni量が74〜80％、Cu
量が10％以下のものが実用に供されている。しか
しながらCu量が10％を越すものでは、鋳造時に
Cuの偏析が生じるために成分コントロールが難
しく、さらに熱間加工性を著しく劣化させるとい
う欠点があるため、実用化が困難であつた。
本発明者は、既に、特願昭56−197617号（特公
昭62−5973号）において、共同発明者の一人とし
て、重量％でNi量が57〜74％、Cu量が12〜32％、
残部Feからなる合金にMg、SiおよびMnを少量
添加、特にMgを0.001〜0.02％添加することによ
り、熱間加工性が著しく改善され、また磁性特性
についてもJIS−PC材と同等レベルを有するこ
と、さらに鋳造時に生ずるCuの偏析は、鋳造の
際の冷却速度を調整することにより改善され、イ
ンゴツト内におけるCu量のばらつきを±0.05％以
内におさえることができることを明らかにした。
また、本発明者は、特願昭56−200045（特公昭
62−5974号）において、同じ共同発明者と共に、
重量でNi57〜74％、Cu12〜32％、残鉄からなる
合金のFeの一部を、0.3〜3.0％Siおよび0.001〜
0.02％Mgで置きかえることにより、三元合金よ
りも透磁率が数段向上し、熱間加工性および耐食
性が改善されることを明らかにした。
しかし、これらの合金を磁気ヘツド用シールド
ケースとして用いた場合耐摩耗性は必ずしも十分
なものではなかつた。そこで耐摩耗性を向上させ
るべく実験を重ねた結果、Zrの少量添加が耐摩
耗性の改善に寄与し、さらに耐食性をも向上する
ことを見い出した。
本発明は以上の考察に基づきなされたものであ
る。すなわち本発明合金は、重量％でNi57〜74
％、Cu12〜32％、Si0.01〜３％、Zr0.05〜１％、
Mg0.001〜0.02％および残部がFeからなることを
特徴とする。
ここでNiは57〜74％の範囲で高透磁率を有す
るが、Niが57％未満では透磁率が低下し、耐食
性も著しく劣り、また74％を越えるとCu量12％
以上の添加により透磁率の低下が著しい。さらに
Niが74％を越えるものは、省資源低価格化を考
慮すれば工業的に不利となる。
Cuは12〜32％の範囲内では高透磁率を有する
がCuは12％未満ではNi量が74％を越えないと高
透磁率が得られず、Cuが32％を越えると初透磁
率μiが低下し熱間加工性も劣化する。
Siは、本合金の耐食性を改善すると共に磁歪お
よび磁性異方性を小さくするために添加するもの
である。Siを添加することにより磁性焼鈍の際に
合金表面層に薄いSiの酸化被覆が形成され、これ
が一種の不働態被膜として働き耐食性を向上させ
る。Siの酸化被覆を形成させるためにはSiを0.3
％以上添加する必要があり、0.3％未満では、酸
化被膜が形成されず耐食性を劣化させる。またSi
を3.0％越えて添加しても、酸化被覆が形成され
耐食性を向上させるが、同時に磁束密度B10が著
しく低下すると共に磁歪および磁気異方性が大き
くなる。以上のことからSiの添加量は0.3〜3.0％
の範囲が耐食性を高めさらに磁歪および磁気異方
性を小さくするために好適である。Siが0.01〜0.3
％の場合はSiはおもに脱酸剤として働き耐食性を
向上させ得ないが、Zrの効果により耐食性は十
分満足し得るものとなる。従つてSiは0.01〜３％
の範囲で良い。
Zrは耐摩耗性および耐食性を向上させるため
に添加するもので、0.05％未満では効果が明らか
でなく１％を越えると耐摩耗性および耐食性はさ
らに向上するが熱間加工性が著しく劣化する。
Mgは熱間加工性を改善するために添加するも
ので0.001％未満では効果は現われず、0.02％を
越えると初透磁率が低下し実用に供し得なくな
る。
なお本発明合金に脱酸剤、脱硫剤としてAl、
Ｃ、Ca、Mn等を総量で１％以下添加してもよ
い。
次に実施例を説明する。
実施例
表１に示す組成になるように溶解した後、鋳型
に鋳込み、Cuの偏析の生じない適当な冷却速度
で鋳塊を得た。この鋳塊を通常の熱間加工および
冷間加工により板厚0.5mmの板材を作製した。こ
こで熱間加工時にカド割れ、耳割れ等が生ぜず熱
間加工性は良好であつた。そしてこれらの板材よ
り磁気特性測定用リング（外径45mmφ、内径33mm
φ）、耐食性試験用試料（50mm×50mm）および耐
摩耗性試験用にオーデイオ用磁気ヘツドケースを
作製しこれらの試料に磁性焼鈍を施した後、次の
項目について調査した。
Γ磁気特性：初透磁率μi
Γ耐食性：塩水噴霧試験（JIS Z2371）
Γ耐摩耗性：γ−Fe2O3磁気テープを使用しオー
トリバース型カセツトデツキ（テープ速度4.75
cm／secにより100時間連続走行後の摩耗深さ
これらの結果を表１に示す。
The present invention relates to a magnetic alloy that has good magnetic properties when applied to magnetic shielding members that require high magnetic permeability, and that has improved hot workability without losing magnetic properties. Magnetic shielding members using Ni-Fe based high magnetic permeability alloys are widely used, for example, as shielding cases for magnetic heads in magnetic recording devices such as tape recorders. Among them, high Ni containing Mo, Cu, etc.
Permalloy (JIS-PC material) and low Ni permalloy (JIS-PB material) are often used. The former has high magnetic permeability and high corrosion resistance, but it uses expensive Ni.
It contains a large amount of over 76% by weight (hereinafter simply referred to as %), and also contains expensive Mo, so it has the disadvantage of being expensive among magnetic alloys. In addition, the latter has a Ni content of about 45%, so it is inexpensive and
The magnetic flux density B 10 at 100 oersted is
Although it is high at 14,000 Gauss, it has the drawbacks of extremely poor corrosion resistance and initial magnetic permeability μ i of 5,000, which is lower than the former. For example, in order to use inexpensive 45% Ni--Fe permalloy as a head case for magnetic shielding, it is necessary to perform plating treatment as a rust prevention treatment, which is industrially disadvantageous. Therefore, with conventional JIS-PC materials and PB materials, it is difficult to obtain magnetic alloy materials that have excellent magnetic properties, high corrosion resistance, and are inexpensive. However, from an industrial perspective, there is a strong demand for inexpensive magnetic alloys that have excellent magnetic properties, hot workability, and corrosion resistance. The present invention has been made in response to the above needs,
The object of the present invention is to provide a new magnetic alloy that does not contain any expensive Mo and further reduces the expensive Ni content without impairing the characteristics of the JIS-PC material. Research on Ni-Fe-Cu alloys, which are made by adding Cu to Ni-Fe alloys, has been conducted for a long time, and it is well known that they have excellent magnetic properties (for example, "Ferromagnetism" by R. M. Bozorth). ,D.
van Nostrand Co.1951), Ni content is 74-80%, Cu
Products with a content of 10% or less are in practical use. However, if the Cu content exceeds 10%,
It is difficult to control the composition due to the segregation of Cu, and furthermore, it has the disadvantage of significantly deteriorating hot workability, making it difficult to put it into practical use. The present inventor has already disclosed, as one of the co-inventors, in Japanese Patent Application No. 56-197617 (Japanese Patent Publication No. 62-5973) that the amount of Ni is 57 to 74% by weight, the amount of Cu is 12 to 32%,
By adding small amounts of Mg, Si, and Mn, especially 0.001 to 0.02% Mg, to an alloy consisting mostly of Fe, hot workability is significantly improved, and the magnetic properties are also at the same level as JIS-PC materials. Furthermore, it was revealed that the segregation of Cu that occurs during casting can be improved by adjusting the cooling rate during casting, and that the variation in the amount of Cu within the ingot can be suppressed to within ±0.05%. In addition, the present inventor also applied for patent application No. 56-200045.
No. 62-5974), together with the same co-inventor,
Part of the alloy consists of 57~74% Ni, 12~32% Cu, residual iron by weight, 0.3~3.0% Si and 0.001~
It was revealed that by replacing it with 0.02% Mg, the magnetic permeability was improved by several orders of magnitude compared to the ternary alloy, and the hot workability and corrosion resistance were improved. However, when these alloys are used as a shield case for a magnetic head, the wear resistance is not necessarily sufficient. As a result of repeated experiments to improve wear resistance, it was discovered that adding a small amount of Zr contributes to improving wear resistance and also improves corrosion resistance. The present invention has been made based on the above considerations. That is, the alloy of the present invention has Ni57 to Ni74 in weight%.
%, Cu12~32%, Si0.01~3%, Zr0.05~1%,
It is characterized by consisting of 0.001 to 0.02% Mg and the balance Fe. Here, Ni has a high magnetic permeability in the range of 57 to 74%, but if the Ni content is less than 57%, the magnetic permeability decreases and the corrosion resistance is also significantly inferior, and if it exceeds 74%, the Cu content increases by 12%.
The above addition causes a significant decrease in magnetic permeability. moreover
Products with a Ni content of more than 74% are industrially disadvantageous in terms of saving resources and lowering prices. Cu has high magnetic permeability within the range of 12 to 32%, but when Cu is less than 12%, high magnetic permeability cannot be obtained unless the Ni amount exceeds 74%, and when Cu exceeds 32%, the initial permeability μ i decreases and hot workability also deteriorates. Si is added to improve the corrosion resistance of this alloy and to reduce magnetostriction and magnetic anisotropy. By adding Si, a thin Si oxide coating is formed on the alloy surface layer during magnetic annealing, which acts as a kind of passive coating and improves corrosion resistance. In order to form an oxide coating of Si, add 0.3
% or more, and if it is less than 0.3%, no oxide film is formed and corrosion resistance deteriorates. Also, Si
Even if more than 3.0% of B is added, an oxide coating is formed and the corrosion resistance is improved, but at the same time, the magnetic flux density B 10 decreases significantly and the magnetostriction and magnetic anisotropy increase. Based on the above, the amount of Si added is 0.3 to 3.0%.
The range is suitable for increasing corrosion resistance and further reducing magnetostriction and magnetic anisotropy. Si is 0.01~0.3
%, Si mainly acts as a deoxidizing agent and cannot improve corrosion resistance, but the effect of Zr makes corrosion resistance sufficiently satisfactory. Therefore, Si is 0.01 to 3%
Good within the range. Zr is added to improve wear resistance and corrosion resistance; if it is less than 0.05%, the effect is not obvious, and if it exceeds 1%, wear resistance and corrosion resistance are further improved, but hot workability is significantly deteriorated. Mg is added to improve hot workability, and if it is less than 0.001%, no effect will be seen, and if it exceeds 0.02%, the initial magnetic permeability will decrease, making it impossible to put it into practical use. The alloy of the present invention contains Al as a deoxidizing agent and desulfurizing agent.
C, Ca, Mn, etc. may be added in a total amount of 1% or less. Next, an example will be described. Example After melting to have the composition shown in Table 1, the ingot was poured into a mold and an ingot was obtained at an appropriate cooling rate to prevent segregation of Cu. This ingot was subjected to conventional hot working and cold working to produce a plate with a thickness of 0.5 mm. Here, no corner cracks, edge cracks, etc. occurred during hot working, and hot workability was good. Then, from these plates, a ring for measuring magnetic properties (outer diameter 45mmφ, inner diameter 33mm
φ), a sample for corrosion resistance test (50 mm x 50 mm) and a magnetic head case for audio for wear resistance test were prepared, and after magnetic annealing was performed on these samples, the following items were investigated. Γ Magnetic properties: Initial magnetic permeability μ i Γ Corrosion resistance: Salt spray test (JIS Z2371) Γ Abrasion resistance: Auto-reverse type cassette deck using γ-Fe 2 O 3 magnetic tape (tape speed 4.75
Wear depth after 100 hours of continuous running in cm/sec These results are shown in Table 1.
【表】
以上述べた如くNi−Fe−Cu合金にSi、Zr、
Mgを添加すれば、耐食性および耐摩耗性に優れ
かつ熱間加工性の良好な磁性合金を得ることが可
能である。故にこの合金は例えば磁気記録装置に
おける磁気ヘツドのシールドケースに使用して好
適である。[Table] As mentioned above, Ni-Fe-Cu alloy contains Si, Zr,
By adding Mg, it is possible to obtain a magnetic alloy with excellent corrosion resistance and wear resistance, and good hot workability. Therefore, this alloy is suitable for use, for example, in a shield case for a magnetic head in a magnetic recording device.