JP2013151737A - Aluminum alloy substrate for magnetic disk and method for producing the same - Google Patents
Aluminum alloy substrate for magnetic disk and method for producing the same Download PDFInfo
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Abstract
Description
本発明は、表面に磁性膜を成膜して磁気ディスクとするアルミニウム合金製の基板およびその製造方法に関する。 The present invention relates to an aluminum alloy substrate that forms a magnetic disk by forming a magnetic film on the surface, and a method for manufacturing the same.
コンピュータ等の記録媒体として使用される磁気ディスクは、非磁性の基板に磁性膜を付着させてなる。一般的にこの基板は、軽量かつ高い剛性を有し、平滑な表面であることが要求される。そのため、非磁性で軽量、さらに鏡面加工等により平滑な表面を容易に得ることができる等の理由からアルミニウム合金が使用される。詳しくは、アルミニウム合金板を円環形状等の磁気ディスクの形状に成形し、平坦化、平滑化等の処理の後、その表面に剛性を得るためのＮｉ−Ｐめっき膜等を約１０μｍの厚さに形成して磁気ディスク用基板としている。 A magnetic disk used as a recording medium for a computer or the like has a magnetic film attached to a non-magnetic substrate. In general, this substrate is required to have a light and high rigidity and a smooth surface. Therefore, an aluminum alloy is used because it is non-magnetic, lightweight, and a smooth surface can be easily obtained by mirror finishing or the like. Specifically, an aluminum alloy plate is formed into a magnetic disk shape such as an annular shape, and after processing such as flattening and smoothing, a Ni-P plating film or the like for obtaining rigidity on the surface thereof is about 10 μm thick. This is used as a magnetic disk substrate.
従来、このようなアルミニウム合金板としては、ハードディスクドライブ用の耐衝撃性で必要となる十分な強度を有し、十分な表面平滑性が得られる等の理由からＪＩＳ Ｈ ４０００に規定の５０８６合金（Ａｌ−Ｍｇ合金）が使用されてきた。さらに、磁気ディスク用基板により適するものとするために、表面の微小な凹凸やうねりを抑制し、平滑性を向上させたアルミニウム合金板が開発されている（例えば、特許文献１〜４）。 Conventionally, as such an aluminum alloy plate, the 5086 alloy specified in JIS H 4000 (for example) has sufficient strength necessary for impact resistance for hard disk drives and sufficient surface smoothness can be obtained. Al-Mg alloys) have been used. Furthermore, in order to make it more suitable for a magnetic disk substrate, aluminum alloy plates with improved surface smoothness by suppressing minute irregularities and waviness on the surface have been developed (for example, Patent Documents 1 to 4).
特許文献１には、Ｍｇ：３〜６質量％を含有し、結晶粒径が２５μｍ以下に抑制された磁気ディスク基板用Ａｌ合金板とするために、平坦化のための積付け焼鈍（歪み矯正焼鈍）において、１０℃／分以上で２８０〜５５０℃に加熱し、同温度範囲内で１〜６０分間保持した後、０．５〜１０℃／分で１５０℃まで冷却する発明が開示されている。このような構成とすることにより、微小うねりの発生が少なく、精密切削性が優れるとともに、磁気ディスクの高記録密度化にも十分対応することができるとしている。 Patent Document 1 discloses stacking annealing (distortion correction) for flattening in order to obtain an Al alloy plate for a magnetic disk substrate containing Mg: 3 to 6% by mass and having a crystal grain size of 25 μm or less. In the annealing), an invention is disclosed in which it is heated to 280 to 550 ° C. at 10 ° C./min or more, held for 1 to 60 minutes within the same temperature range, and then cooled to 150 ° C. at 0.5 to 10 ° C./min. Yes. By adopting such a configuration, the generation of minute waviness is reduced, the precision cutting property is excellent, and the recording density of the magnetic disk can be sufficiently coped with.
特許文献２には、Ｍｇ：３．０〜５．０質量％、所定量のＦｅ，Ｓｉ，Ｃｕを含有し、Ｚｎ：０．０５質量％未満とし、さらにＧａ：５０〜４００ｐｐｍ、Ｂｅ：０．５〜１００ｐｐｍを含有し、７μｍ以上の金属間化合物を１０個／ｍｍ2以下とする磁気ディスクアルミニウム合金の発明が開示されている。Ｚｎを所定値未満に規制し、Ｇａ，Ｂｅを特定の範囲とすることで、鏡面仕上げ性および耐食性が良好で、さらに均一微細なＮｉ−Ｐめっき膜を形成することができるとしている。 Patent Document 2 contains Mg: 3.0 to 5.0 mass%, a predetermined amount of Fe, Si, Cu, Zn: less than 0.05 mass%, Ga: 50 to 400 ppm, Be: 0 An invention of a magnetic disk aluminum alloy containing 5 to 100 ppm and containing 10 μm / mm 2 or more of intermetallic compounds of 7 μm or more is disclosed. By restricting Zn to less than a predetermined value and setting Ga and Be within a specific range, it is said that a mirror finish and corrosion resistance are good and a uniform fine Ni—P plating film can be formed.
特許文献３には、Ｍｇ：１〜８質量％を含有し、Ｓｉ，Ｆｅを不純物元素として規制するとともに、Ｇａ：１５０ｐｐｍ以下に規制するという磁気ディスク基板用アルミニウム合金の発明が開示されている。Ｇａを所定値以下に規制することによってマトリクスからの金属間化合物の脱落を抑制し、表面欠陥を生じ難くすることができるとしている。 Patent Document 3 discloses an invention of an aluminum alloy for a magnetic disk substrate that contains Mg: 1 to 8% by mass, regulates Si and Fe as impurity elements, and regulates Ga to 150 ppm or less. By restricting Ga to a predetermined value or less, it is possible to suppress the drop-off of the intermetallic compound from the matrix and make it difficult to cause surface defects.
特許文献４には、Ｍｇ：３．０〜６．０質量％、Ｚｎ：０．２５〜１．０質量％を含有し、さらに所定量のＣｕ，Ｃｒを含有し、Ｆｅ，Ｓｉの各含有量を０．０５質量％以下に規制し、結晶粒界に存在する最大幅０．０２μｍ以上、最大長さ０．１μｍ以上のＡｌ−Ｍｇ−Ｚｎ系金属間化合物の数が１ｍｍあたり平均で１個以下とする磁気ディスク用アルミニウム合金基板の発明が開示されている。さらにその積付け焼鈍条件として、３００〜４００℃に３０分間以上保持した後、３５０〜２００℃の温度範囲において冷却速度２００℃／分以上で急速冷却するとしている。Ｚｎを特定の範囲とすることでジンケート処理後のアルミニウム合金基板表面に生じる結晶粒の分布を反映した模様（結晶粒模様）の形成を抑制し、もってＮｉ−Ｐめっき膜表面の微小な凹凸の発生を抑制し、結果的に表面に微小なうねりが発生することなく、高平坦度および高平滑度な表面を得ることができるとしている。 Patent Document 4 contains Mg: 3.0 to 6.0 mass%, Zn: 0.25 to 1.0 mass%, further contains a predetermined amount of Cu and Cr, and contains Fe and Si. The number of Al—Mg—Zn-based intermetallic compounds having a maximum width of 0.02 μm or more and a maximum length of 0.1 μm or more present at the grain boundaries is 1 on average per 1 mm. An invention of an aluminum alloy substrate for a magnetic disk that is less than or equal to one is disclosed. Furthermore, as the annealing conditions for the stacking, it is assumed that after being held at 300 to 400 ° C. for 30 minutes or more, rapid cooling is performed at a cooling rate of 200 ° C./min or more in a temperature range of 350 to 200 ° C. By making Zn in a specific range, the formation of a pattern (crystal grain pattern) reflecting the distribution of crystal grains generated on the surface of the aluminum alloy substrate after the zincate treatment is suppressed. The generation is suppressed, and as a result, a surface with high flatness and high smoothness can be obtained without generating minute waviness on the surface.
特許文献１〜４に記載されるように、熱処理による結晶粒の粗大化を抑制する等、アルミニウム合金組織を制御することにより、アルミニウム合金板の成形後の積付け焼鈍や磁性膜の成膜等の加熱工程後における、アルミニウム合金板の研削等の表面処理後の表面あるいはＮｉ−Ｐめっき膜の研磨面の平滑性の低下を防止して、磁気ディスクの高記録密度化に対応している。 As described in Patent Documents 1 to 4, by controlling the aluminum alloy structure, such as suppressing grain coarsening due to heat treatment, stacking annealing after forming an aluminum alloy plate, film formation of a magnetic film, etc. After the heating step, the smoothness of the surface after the surface treatment such as grinding of the aluminum alloy plate or the polished surface of the Ni—P plating film is prevented from being lowered, and the recording density of the magnetic disk is increased.
近年は高記録密度化の要求が極めて強く、年々記録密度の向上がなされているが、高記録密度化のためには磁性粒子の微細化を要する。しかし、一般に磁性粒子の微細化とともに保磁力が低下するので、室温程度の熱エネルギーでも減磁する「熱揺らぎ」と呼ばれる現象が生じ、記録されたデータすなわち磁化方向を保持することができなくなる。熱揺らぎのため、現行の垂直記録方式での記録密度の限界は、１Ｔｂ／ｉｎｃｈ2（テラバイト毎平方インチ）といわれている。そこで、さらなる高密度記録化を図る技術として、熱アシスト磁気記録方式が注目されている。 In recent years, the demand for higher recording density has been extremely strong, and the recording density has been improved year by year. However, in order to increase the recording density, it is necessary to make the magnetic particles finer. However, since the coercive force generally decreases with the miniaturization of magnetic particles, a phenomenon called “thermal fluctuation” occurs that demagnetizes even with thermal energy at about room temperature, and the recorded data, that is, the magnetization direction cannot be maintained. Due to thermal fluctuations, the limit of recording density in the current perpendicular recording system is said to be 1 Tb / inch 2 (terabyte per square inch). In view of this, the heat-assisted magnetic recording method has attracted attention as a technique for achieving higher density recording.
熱アシスト磁気記録方式では、磁気ディスク上の記録しようとする微小領域をレーザー等で瞬間的に加熱しながら、加熱された微小領域を磁気ヘッドで所望の磁化方向としてデータを記録する。磁性材料のキュリー温度近傍まで加熱することで一時的に保磁力を下げて、常温に戻ると保磁力が回復されるので、微細化された磁性粒子であっても減磁しないような高い保磁力を有し、これまでの磁気ヘッドでは記録できなかった磁性材料を適用することができる。すなわち熱アシスト磁気記録方式で記録すれば、磁性粒子の微粒子化と安定した記録を両立できることから、超高密度記録化の実現に向けて研究、開発が進められている。 In the heat-assisted magnetic recording method, data is recorded with a magnetic head as a desired magnetization direction while a minute area to be recorded on a magnetic disk is instantaneously heated with a laser or the like. The coercive force is temporarily lowered by heating to the vicinity of the Curie temperature of the magnetic material, and the coercive force is recovered when the temperature returns to room temperature. It is possible to apply a magnetic material that cannot be recorded by a conventional magnetic head. In other words, if recording is performed by the heat-assisted magnetic recording method, the magnetic particles can be made fine and stable recording can be achieved at the same time. Therefore, research and development are being promoted toward realization of ultra-high density recording.
ここで、熱アシスト磁気記録方式に好適な磁性材料としてＦｅＰｔ系合金が知られている。このＦｅＰｔ系合金は、成膜時に４００〜５００℃程度という高温で数〜１０秒間程度の熱処理が必要である。 Here, an FePt-based alloy is known as a magnetic material suitable for the heat-assisted magnetic recording system. This FePt-based alloy requires a heat treatment at a high temperature of about 400 to 500 ° C. for several to 10 seconds at the time of film formation.
しかしながら、現行の磁気ディスクに適用されている磁性膜の成膜は３００℃以下でのスパッタリングであり、従来用いられてきたＪＩＳ５０８６合金や特許文献１〜４に記載されている磁気ディスク用アルミニウム合金基板では、５００℃もの高温に加熱されると、歪んで平坦度が悪化する。なお、熱アシスト磁気記録方式による書込自体は、磁気ディスクの磁性膜における微小領域に限定されてかつ瞬間的に極めて短時間加熱されるだけであるので、磁気ディスク用アルミニウム合金基板への影響は殆どない。また、熱アシスト磁気記録方式対応の磁気ディスクにおいては、磁性膜の下地膜として、磁性膜の成膜時の高温の加熱により、表面の平滑性が損なわれず、かつ磁性を有することのない高耐熱性の非磁性膜が適用される。 However, the film formation of the magnetic film applied to the current magnetic disk is sputtering at 300 ° C. or less, and the JIS5086 alloy used conventionally and the aluminum alloy substrate for magnetic disk described in Patent Documents 1 to 4 are used. Then, when heated to a high temperature as high as 500 ° C., the flatness deteriorates due to distortion. Note that writing by the heat-assisted magnetic recording method is limited to a minute region in the magnetic film of the magnetic disk and is only heated for a very short time, so there is no influence on the aluminum alloy substrate for the magnetic disk. Almost no. In addition, in a magnetic disk compatible with the heat-assisted magnetic recording system, the surface smoothness of the magnetic film is not impaired by the high-temperature heating during the formation of the magnetic film, and the magnetic film does not have magnetism. A non-magnetic film is applied.
本発明は前記問題に鑑みてなされたものであり、５００℃という高温に加熱されても平坦度の悪化を抑制することのできる磁気ディスク用アルミニウム合金基板およびその製造方法を提供することを課題とする。 The present invention has been made in view of the above problems, and it is an object of the present invention to provide an aluminum alloy substrate for a magnetic disk that can suppress deterioration of flatness even when heated to a high temperature of 500 ° C. and a method for manufacturing the same. To do.
本発明者らは、従来よりも高強度であり、かつ５００℃という高温に加熱されても平坦度の変化の小さいアルミニウム合金基板を鋭意研究した結果、以下のような手段とすることで前記課題を解決することができることを見出し、本発明を完成するに至った。 As a result of intensive studies on an aluminum alloy substrate that has higher strength than the conventional one and has a small change in flatness even when heated to a high temperature of 500 ° C., the above-mentioned problem has been achieved by the following means. Has been found to be able to be solved, and the present invention has been completed.
すなわち本発明に係る磁気ディスク用アルミニウム合金基板は、Ｍｇ：３．５質量％以上６質量％以下を含有し、残部がＡｌおよび不可避的不純物からなるアルミニウム合金からなり、５００℃で１０秒間加熱された前後における平坦度の変化量が５μｍ以下であることを特徴とする。また、前記アルミニウム合金は、Ｃｒ：０．０５質量％以上０．６質量％以下、Ｍｎ：０．０５質量％以上１．５質量％以下、Ｚｒ：０．０５質量％以上０．６質量％以下の少なくとも１種を含有することが好ましい。 That is, the aluminum alloy substrate for a magnetic disk according to the present invention contains Mg: 3.5% by mass or more and 6% by mass or less, and the balance is made of an aluminum alloy composed of Al and inevitable impurities, and is heated at 500 ° C. for 10 seconds. The amount of change in flatness before and after is 5 μm or less. The aluminum alloy contains Cr: 0.05% by mass to 0.6% by mass, Mn: 0.05% by mass to 1.5% by mass, Zr: 0.05% by mass to 0.6% by mass It is preferable to contain at least one of the following.
このように、Ｍｇを所定量含有しているので磁気ディスク用アルミニウム合金基板として必要な強度を確保することができ、また、５００℃で１０秒間加熱された前後における平坦度の変化量が５μｍ以下に制御されているので、５００℃の高温処理を要する磁気ディスクのためのアルミニウム合金基板とすることができる。さらにＣｒ，Ｍｎ，Ｚｒを含有することにより、強度がいっそう向上し、また加熱されても結晶粒の粗大化が抑制されて、表面の平滑性が低下し難い磁気ディスク用アルミニウム合金基板となる。 As described above, since a predetermined amount of Mg is contained, the necessary strength as an aluminum alloy substrate for a magnetic disk can be secured, and the amount of change in flatness before and after being heated at 500 ° C. for 10 seconds is 5 μm or less. Therefore, an aluminum alloy substrate for a magnetic disk requiring a high temperature treatment at 500 ° C. can be obtained. Further, by containing Cr, Mn, and Zr, the strength is further improved, and even when heated, the coarsening of crystal grains is suppressed, and the aluminum alloy substrate for a magnetic disk in which the smoothness of the surface is hardly lowered is obtained.
また、本発明に係る磁気ディスク用アルミニウム合金基板の製造方法は、前記アルミニウム合金からなるアルミニウム合金板を成形する成形工程と、前記成形したアルミニウム合金板を積付け焼鈍にて平坦化する積付け焼鈍工程と、を行うものであって、前記積付け焼鈍工程が、前記成形したアルミニウム合金板を、加熱速度２℃／分以下で４００℃以上に加熱して、４００℃以上で２時間以上保持した後、冷却速度２℃／分以下で２００℃以下に冷却することを特徴とする。 The method for manufacturing an aluminum alloy substrate for a magnetic disk according to the present invention includes a forming step of forming an aluminum alloy plate made of the aluminum alloy, and a stacking annealing for flattening the formed aluminum alloy plate by stacking annealing. The stacking and annealing step heats the formed aluminum alloy plate to 400 ° C. or higher at a heating rate of 2 ° C./min and holds it at 400 ° C. or higher for 2 hours or longer. Then, it is cooled to 200 ° C. or less at a cooling rate of 2 ° C./min or less.
かかる手順によれば、５００℃で１０秒間加熱された前後における平坦度の変化量が５μｍ以下である本発明に係る磁気ディスク用アルミニウム合金基板を製造することができる。 According to such a procedure, the aluminum alloy substrate for a magnetic disk according to the present invention in which the amount of change in flatness before and after being heated at 500 ° C. for 10 seconds can be 5 μm or less can be produced.
本発明に係るアルミニウム合金基板によれば、５００℃の高温下で成膜される磁性材料が設けられる磁気ディスクを製造することができる。また、本発明に係るアルミニウム合金基板の製造方法によれば、前記アルミニウム合金基板を製造することができる。 According to the aluminum alloy substrate according to the present invention, a magnetic disk provided with a magnetic material formed at a high temperature of 500 ° C. can be manufactured. Moreover, according to the manufacturing method of the aluminum alloy substrate which concerns on this invention, the said aluminum alloy substrate can be manufactured.
以下、本発明に係る磁気ディスク用アルミニウム合金基板およびその製造方法を実施するため形態を詳細に説明する。 Hereinafter, embodiments for carrying out an aluminum alloy substrate for a magnetic disk and a manufacturing method thereof according to the present invention will be described in detail.
〔磁気ディスク用アルミニウム合金基板〕
本発明に係る磁気ディスク用アルミニウム合金基板は、磁気ディスク、特に熱アシスト磁気記録方式対応の磁気ディスクの平坦度を矯正された基板（ブランク）であり、表面を研削され、その上に剛性を得るための下地膜を形成された後、ＦｅＰｔ系合金のような高い保磁力を有する磁性膜が形成されて磁気ディスクになる。本発明に係る磁気ディスク用アルミニウム合金基板は、形状および寸法を特に規定するものではないが、板厚０．７８〜１．８ｍｍ、外径６６〜９６ｍｍ、内径１９〜２４ｍｍの円環形状の板である、一般的な２．５〜３．５インチタイプの磁気ディスクのブランクに適用することができる。
[Aluminum alloy substrate for magnetic disk]
An aluminum alloy substrate for a magnetic disk according to the present invention is a substrate (blank) in which the flatness of a magnetic disk, particularly a magnetic disk compatible with a heat-assisted magnetic recording method, is corrected, and the surface thereof is ground to obtain rigidity thereon. After the base film is formed, a magnetic film having a high coercive force such as an FePt-based alloy is formed to form a magnetic disk. The aluminum alloy substrate for a magnetic disk according to the present invention does not particularly define the shape and dimensions, but an annular plate having a thickness of 0.78 to 1.8 mm, an outer diameter of 66 to 96 mm, and an inner diameter of 19 to 24 mm. It can be applied to a blank of a general 2.5 to 3.5 inch type magnetic disk.
本発明に係る磁気ディスク用アルミニウム合金基板（以下、アルミニウム合金基板という）は、Ｍｇ：３．５質量％以上６質量％以下を含有し、残部がＡｌおよび不可避的不純物からなるアルミニウム合金からなる。また、５００℃で１０秒間加熱された前後における平坦度の変化量が５μｍ以下である。はじめに、本発明に係るアルミニウム合金基板を形成するアルミニウム合金を構成する各要素について説明する。 The aluminum alloy substrate for magnetic disks according to the present invention (hereinafter referred to as an aluminum alloy substrate) is made of an aluminum alloy containing Mg: 3.5% by mass or more and 6% by mass or less, with the balance being Al and inevitable impurities. Further, the amount of change in flatness before and after being heated at 500 ° C. for 10 seconds is 5 μm or less. First, each element constituting the aluminum alloy forming the aluminum alloy substrate according to the present invention will be described.
（Ｍｇ：３．５質量％以上６質量％以下）
Ｍｇは、磁気ディスク用のアルミニウム合金基板として必要な強度（耐力９５ＭＰａ以上）を得るための必須元素である。強度が不十分では、磁気ディスクに製造されたとき、例えば落下時の衝撃で変形し易かったり、記録時に磁気ヘッドの接触による傷が付き易いためにハードディスクドライブの耐衝撃性のスペックを満足することができない。十分な強度とするために、Ｍｇの含有量は３．５質量％以上とし、好ましくは３．８質量％以上、より好ましくは４質量％以上、さらに好ましくは４．５質量％以上である。一方、Ｍｇの含有量が６質量％を超えると、熱間割れ感受性が高くなり、熱間圧延中に割れが生じる虞がある。したがって、Ｍｇの含有量は、６質量％以下とし、好ましくは５．５質量％以下、さらに好ましくは５質量％以下である。
(Mg: 3.5 mass% or more and 6 mass% or less)
Mg is an essential element for obtaining the strength required for an aluminum alloy substrate for a magnetic disk (yield strength of 95 MPa or more). Insufficient strength, when manufactured to a magnetic disk, for example, it easily deforms due to an impact at the time of dropping, or it is easily damaged by the contact of the magnetic head at the time of recording, so it satisfies the impact resistance specifications of the hard disk drive I can't. In order to obtain sufficient strength, the Mg content is 3.5% by mass or more, preferably 3.8% by mass or more, more preferably 4% by mass or more, and further preferably 4.5% by mass or more. On the other hand, if the Mg content exceeds 6% by mass, the hot cracking sensitivity becomes high, and there is a possibility that cracking may occur during hot rolling. Therefore, the Mg content is 6% by mass or less, preferably 5.5% by mass or less, and more preferably 5% by mass or less.
本発明に係るアルミニウム合金基板を形成するアルミニウム合金は、前記のＭｇ：３．５質量％以上６質量％以下に加え、Ｃｒ：０．０５質量％以上０．６質量％以下、Ｍｎ：０．０５質量％以上１．５質量％以下、Ｚｒ：０．０５質量％以上０．６質量％以下の少なくとも１種をさらに含有することが好ましい。 The aluminum alloy forming the aluminum alloy substrate according to the present invention includes Mg: 3.5% by mass to 6% by mass, Cr: 0.05% by mass to 0.6% by mass, and Mn: 0. It is preferable to further contain at least one of 05 mass% to 1.5 mass%, Zr: 0.05 mass% to 0.6 mass%.
（Ｃｒ：０．０５質量％以上０．６質量％以下、Ｍｎ：０．０５質量％以上１．５質量％以下、Ｚｒ：０．０５質量％以上０．６質量％以下の少なくとも１種）
Ｃｒ，Ｍｎ，Ｚｒは、それぞれアルミニウム合金の強度を高める効果があり、この効果を得るために、これらの元素の少なくとも１種を０．０５質量％以上含有することが好ましい。また、Ｃｒ，Ｍｎ，Ｚｒは、それぞれ加熱による結晶粒の粗大化を抑制する効果もあり、積付け焼鈍、あるいはさらに５００℃の高温下での磁性膜の成膜による表面の平滑性の低下を防止することができる。この効果を得るために、Ｚｒは前記と同様に０．０５質量％以上とし、Ｃｒは０．２質量％以上、Ｍｎは０．３質量％以上とすることがさらに好ましい。また、Ｃｒ，Ｍｎ，Ｚｎの２種以上を組み合わせて含有することで、前記範囲未満の含有量であっても同等の効果が得られる。一方、Ｃｒ，Ｚｒは０．６質量％、Ｍｎは１．５質量％をそれぞれ超えると、アルミニウム合金の融点が高くなるため、溶解時に溶け残ったり、溶湯の粘度が高くなって鋳造困難となる場合がある。さらにＣｒ系、Ｍｎ系、Ｚｒ系の粗大な初晶が晶出し、このようなアルミニウム合金基板を磁気ディスクに製造すると、磁気ディスクドライブに組み込んだときにヘッドクラッシュを生じる虞がある。したがって、Ｃｒの含有量は０．０５〜０．６質量％、Ｍｎの含有量は０．０５〜１．５質量％、Ｚｒの含有量は０．０５〜０．６質量％とする。
(Cr: 0.05 mass% or more and 0.6 mass% or less, Mn: 0.05 mass% or more and 1.5 mass% or less, Zr: 0.05 mass% or more and 0.6 mass% or less)
Cr, Mn, and Zr each have an effect of increasing the strength of the aluminum alloy, and in order to obtain this effect, it is preferable that 0.05% by mass or more of at least one of these elements is contained. In addition, Cr, Mn, and Zr have an effect of suppressing the coarsening of crystal grains due to heating, respectively, and decrease the smoothness of the surface by stacking annealing or by forming a magnetic film at a high temperature of 500 ° C. Can be prevented. In order to obtain this effect, it is more preferable that Zr is 0.05% by mass or more as described above, Cr is 0.2% by mass or more, and Mn is 0.3% by mass or more. Moreover, even if it is content less than the said range by containing 2 or more types of Cr, Mn, Zn in combination, an equivalent effect is acquired. On the other hand, if Cr and Zr exceed 0.6% by mass and Mn exceeds 1.5% by mass, the melting point of the aluminum alloy increases, so that it remains undissolved during melting or the viscosity of the molten metal increases, making casting difficult. There is a case. In addition, coarse primary crystals of Cr, Mn, and Zr are crystallized, and when such an aluminum alloy substrate is manufactured on a magnetic disk, there is a risk of head crash when incorporated in a magnetic disk drive. Therefore, the Cr content is 0.05 to 0.6 mass%, the Mn content is 0.05 to 1.5 mass%, and the Zr content is 0.05 to 0.6 mass%.
（不可避的不純物）
不可避的不純物として、例えば、Ｓｉ，Ｆｅ，Ｃｕ，Ｚｎ，Ｔｉ，Ｂ，Ｖ等が挙げられる。Ｓｉ，Ｆｅは金属間化合物を形成するため、含有量は少ないほど好ましいが、Ｓｉ：０．０３質量％以下、Ｆｅ：０．０５質量％以下であれば本発明の所望する効果に影響しない。また、Ｃｕ：０．０７質量％以下、Ｚｎ：０．３８質量％以下、Ｔｉ，Ｂ，Ｖ：各０．０１質量％以下であれば本発明の所望する効果に影響しない。
(Inevitable impurities)
Examples of inevitable impurities include Si, Fe, Cu, Zn, Ti, B, and V. Since Si and Fe form an intermetallic compound, the smaller the content, the better. However, Si: 0.03% by mass or less and Fe: 0.05% by mass or less do not affect the desired effect of the present invention. Moreover, if Cu: 0.07 mass% or less, Zn: 0.38 mass% or less, and Ti, B, V: 0.01 mass% or less respectively, it does not affect the effect which this invention desires.
（５００℃で１０秒間加熱された前後における平坦度の変化量：５μｍ以下）
本発明に係るアルミニウム合金基板は、熱アシスト磁気記録方式に好適なＦｅＰｔ系合金を磁性膜として備えた磁気ディスクのための基板とすることを可能とする。そのため、ＦｅＰｔ系合金膜の成膜における熱処理を模擬して、５００℃で１０秒間の加熱をして、前後の平坦度の変化量を制御する。アルミニウム合金基板の平坦度が５μｍを超えて変化すると、磁気ディスクに製造されたときに必要な平坦性が得られないため、磁気ディスク用の基板として不適である。したがって、５００℃で１０秒間加熱された前後における平坦度の変化量は５μｍ以下とし、少ないほど好ましい。このような、高温での歪みを抑制したアルミニウム合金基板は、後記の製造方法（積付け焼鈍条件）によって得ることができる。なお、アルミニウム合金基板の平坦度とは、アルミニウム合金基板の表面の最も高い点と最も低い点との差（Ｐ−Ｖ値）であり、例えば半導体レーザーによる干渉縞により測定することができる。
(Change in flatness before and after heating at 500 ° C. for 10 seconds: 5 μm or less)
The aluminum alloy substrate according to the present invention can be used as a substrate for a magnetic disk provided with a FePt-based alloy suitable for a heat-assisted magnetic recording system as a magnetic film. Therefore, the amount of change in flatness before and after is controlled by simulating the heat treatment in forming the FePt-based alloy film and heating at 500 ° C. for 10 seconds. If the flatness of the aluminum alloy substrate changes beyond 5 μm, the flatness required when the magnetic disk is manufactured cannot be obtained, so that it is not suitable as a substrate for a magnetic disk. Therefore, the amount of change in flatness before and after being heated at 500 ° C. for 10 seconds is 5 μm or less, and the smaller the better. Such an aluminum alloy substrate in which distortion at high temperature is suppressed can be obtained by a manufacturing method (stacking annealing condition) described later. The flatness of the aluminum alloy substrate is a difference (P-V value) between the highest point and the lowest point on the surface of the aluminum alloy substrate, and can be measured, for example, by interference fringes by a semiconductor laser.
〔磁気ディスク用アルミニウム合金基板の製造方法〕
本発明に係る磁気ディスク用アルミニウム合金基板は、前記成分のアルミニウム合金を、従来の製造方法と同様に、溶解、鋳造、均質化処理、熱間圧延、冷間圧延、さらに途中に必要に応じて焼鈍（荒鈍や中間焼鈍）により圧延板（アルミニウム合金板）とし、このアルミニウム合金板を打抜き等により円環形状等の所望の形状に成形する成形工程と、成形したアルミニウム合金板を両面から加圧した状態で焼鈍する（積付け焼鈍）ことにより、成形時の歪みを矯正して平坦化する積付け焼鈍工程と、を行って製造される。本発明に係る磁気ディスク用アルミニウム合金基板は、成形工程までは公知の製造方法と同様とすることができ、前記したように、積付け焼鈍工程の条件により高温の処理における歪みを抑制する。以下、本発明に係る磁気ディスク用アルミニウム合金基板の積付け焼鈍条件について、詳細に説明する。
[Method of manufacturing aluminum alloy substrate for magnetic disk]
The aluminum alloy substrate for a magnetic disk according to the present invention is prepared by melting, casting, homogenizing treatment, hot rolling, cold rolling, and in the middle of the above-described aluminum alloy as in the conventional manufacturing method. A rolled plate (aluminum alloy plate) is formed by annealing (roughening or intermediate annealing), and this aluminum alloy plate is formed into a desired shape such as an annular shape by punching, and the formed aluminum alloy plate is added from both sides. By performing annealing in a pressed state (stacking annealing), the stacking annealing process is performed by correcting and flattening distortion during molding. The aluminum alloy substrate for a magnetic disk according to the present invention can be the same as the known manufacturing method until the forming step, and as described above, the distortion in the high temperature treatment is suppressed depending on the conditions of the stack annealing step. Hereinafter, the stacking annealing conditions of the aluminum alloy substrate for magnetic disks according to the present invention will be described in detail.
特許文献１にも記載されているように、従来は、結晶粒の微細化のために積付け焼鈍温度へ１０℃／分以上で加熱したり、特許文献４に記載されているように、粒界へのＡｌ−Ｍｇ−Ｚｎ系金属間化合物の析出防止の観点から、積付け焼鈍後（温度保持後）に２００℃／分以上で急速冷却していた。しかし、発明者が鋭意研究したところ、５００℃という高温で処理した際の平坦度の悪化を防止するためには、積付け焼鈍における加熱中および冷却中の熱歪みを防止することが重要であることが明らかになった。５００℃に加熱された場合のアルミニウム合金基板の変形は、アルミニウム合金基板の内部歪が開放されるために生じていると考えられる。そのため、積付け焼鈍時に内部歪みを完全に除去する必要がある。また、加熱（昇温）時や焼鈍後の冷却（降温）時におけるアルミニウム合金基板の表面や端面と内部との温度差による熱応力の導入を極力防止するために、急激な温度変化すなわち急速加熱や急速冷却を避ける必要がある。一方、結晶粒の粗大化等は、アルミニウム合金の成分を前記の通り制御することで抑制することができる。 As described in Patent Document 1, conventionally, for refining crystal grains, heating is performed at a temperature of 10 ° C./min or more to a stacking annealing temperature, or as described in Patent Document 4, From the viewpoint of preventing precipitation of Al—Mg—Zn-based intermetallic compounds on the boundary, rapid cooling was performed at 200 ° C./min or more after stacking annealing (after maintaining the temperature). However, as a result of extensive research by the inventor, it is important to prevent thermal distortion during heating and cooling during stacking annealing in order to prevent deterioration in flatness when processed at a high temperature of 500 ° C. It became clear. It is considered that the deformation of the aluminum alloy substrate when heated to 500 ° C. occurs because the internal strain of the aluminum alloy substrate is released. Therefore, it is necessary to completely remove the internal strain at the time of stacking annealing. In order to prevent the introduction of thermal stress due to the temperature difference between the surface and end face of the aluminum alloy substrate and the inside during heating (heating) and cooling after cooling (cooling), rapid temperature changes, that is, rapid heating And rapid cooling should be avoided. On the other hand, coarsening of crystal grains can be suppressed by controlling the components of the aluminum alloy as described above.
そのため、本発明に係る磁気ディスク用アルミニウム合金基板の製造方法は、前記成分のアルミニウム合金からなるアルミニウム合金板を、成形して、積付け焼鈍にて平坦化する際の積付け焼鈍が、成形したアルミニウム合金板を、加熱速度２℃／分以下で４００℃以上に加熱して、４００℃以上で２時間以上保持した後、冷却速度２℃／分以下で２００℃以下に冷却するものとする。 Therefore, in the method for manufacturing an aluminum alloy substrate for a magnetic disk according to the present invention, an aluminum alloy plate made of the above-described aluminum alloy is molded, and the annealing for forming the flattening by the stacking annealing is performed. The aluminum alloy plate is heated to 400 ° C. or higher at a heating rate of 2 ° C./min or lower, held at 400 ° C. or higher for 2 hours or longer, and then cooled to 200 ° C. or lower at a cooling rate of 2 ° C./min or lower.
積付け焼鈍においてアルミニウム合金板を両面から加圧する方法は、公知の方法を適用することができる。一例として、成形したアルミニウム合金板を複数枚積み重ねて、さらに両端から厚さ２０〜３０ｍｍの一対の治具（スペーサ）で挟み、スペーサ同士をスプリングで連結して互いに近付こうとする方向へ加圧し、この状態で焼鈍する。アルミニウム合金板は、加圧されることによりスペーサと同程度の平坦度まで矯正され、さらにこの状態で焼鈍されることにより形状が固定され、また残留応力が除去される。なお、スプリングでの加圧は、積付け焼鈍で行われる一般的な圧力にて行うことができる。 A known method can be applied as a method of pressing the aluminum alloy plate from both sides in the stacking annealing. As an example, a plurality of molded aluminum alloy plates are stacked and sandwiched between a pair of jigs (spacers) with a thickness of 20 to 30 mm from both ends, and the spacers are connected by springs and added in a direction to approach each other. And anneal in this state. When pressed, the aluminum alloy plate is corrected to the same flatness as the spacer, and further annealed in this state to fix the shape and remove residual stress. In addition, pressurization with a spring can be performed by a general pressure performed by stacking annealing.
（加熱速度：２℃／分以下、冷却速度：２℃／分以下）
加熱速度が２℃／分を超える場合、および冷却速度が２℃／分を超える場合のいずれにおいても、熱応力の発生により内部に歪みが残留し易くなり、磁性膜のスパッタリングでの急速加熱時に平坦度の変化量が増加してしまう。加熱速度が速い場合はさらに、積み重ねられたアルミニウム合金板の内部まで熱が伝わり難いために加熱が不十分となって、歪みが完全に除去されない場合がある。そのため、焼鈍温度（保持温度）への加熱速度を２℃／分以下とし、保持後の冷却速度を２℃／分以下とする。なお、保持後の冷却は、２００℃以下になるまで前記の冷却速度で冷却する。２００℃まで冷却される間に内部歪みは除去されるため、その後は急速冷却してもよい。好ましくは１５０℃以下になるまで、前記の冷却速度で冷却する。
(Heating rate: 2 ° C / min or less, cooling rate: 2 ° C / min or less)
In both cases where the heating rate exceeds 2 ° C./min and the cooling rate exceeds 2 ° C./min, distortion is likely to remain inside due to generation of thermal stress, and during rapid heating during sputtering of the magnetic film The amount of change in flatness increases. Further, when the heating rate is high, the heat is not easily transmitted to the inside of the stacked aluminum alloy plates, so that the heating becomes insufficient and the distortion may not be completely removed. Therefore, the heating rate to the annealing temperature (holding temperature) is set to 2 ° C./min or less, and the cooling rate after holding is set to 2 ° C./min or less. In addition, the cooling after holding | maintenance is cooled at the said cooling rate until it becomes 200 degrees C or less. Since internal strain is removed while cooling to 200 ° C., rapid cooling may be performed thereafter. It cools with the said cooling rate until it becomes preferably 150 degrees C or less.
（焼鈍温度：４００℃以上、保持時間：２時間以上）
積付け焼鈍の焼鈍温度が４００℃未満であったり、保持時間が２時間未満であったりすると、積付け焼鈍時に磁気ディスク用アルミニウム合金基板の残留歪みを完全に除去することができないため、磁性膜のスパッタリングでの急速加熱により平坦性が悪化する。また、残留歪みにより結晶粒の安定性も低下し、加熱時に結晶粒が粗大化しやすくなる。したがって、積付け焼鈍の焼鈍温度は４００℃以上とし、保持時間は２時間以上とする。焼鈍温度は、過剰に高くても効果が向上せず、さらに結晶粒が異常成長するため、４５０℃以下とすることが好ましい。同様に、保持時間５時間を超えて積付け焼鈍を行っても、効果が向上せず、生産性が低下する。
(Annealing temperature: 400 ° C. or higher, holding time: 2 hours or longer)
If the annealing temperature of the stack annealing is less than 400 ° C. or the holding time is less than 2 hours, the residual strain of the aluminum alloy substrate for magnetic disks cannot be completely removed during the stack annealing. The flatness deteriorates due to rapid heating during sputtering. In addition, the stability of the crystal grains decreases due to the residual strain, and the crystal grains are likely to become coarse during heating. Therefore, the annealing temperature of the stacking annealing is set to 400 ° C. or more, and the holding time is set to 2 hours or more. Even if the annealing temperature is excessively high, the effect is not improved and the crystal grains grow abnormally. Therefore, the annealing temperature is preferably set to 450 ° C. or lower. Similarly, even if it performs stacking annealing exceeding holding time 5 hours, an effect will not improve but productivity will fall.
以上、本発明に係る磁気ディスク用アルミニウム合金基板およびその製造方法によれば、Ｍｇを所定量含有することによって磁気ディスク用アルミニウム合金基板として必要な強度を確保し、５００℃で１０秒間加熱された前後における平坦度の変化量を５μｍ以下とすることによって、５００℃に加熱されるスパッタリングで急速加熱が行われても平坦度の悪化を抑制することが可能となる。 As described above, according to the aluminum alloy substrate for a magnetic disk and the method for manufacturing the same according to the present invention, the strength required for an aluminum alloy substrate for a magnetic disk is ensured by containing a predetermined amount of Mg and heated at 500 ° C. for 10 seconds. By making the amount of change in flatness before and after 5 μm or less, it is possible to suppress deterioration of flatness even if rapid heating is performed by sputtering heated to 500 ° C.
次に、本発明に係る磁気ディスク用アルミニウム合金基板およびその製造方法について、本発明の要件を満たす実施例と、満たさない比較例とを例示して、具体的に説明する。 Next, the aluminum alloy substrate for a magnetic disk and the manufacturing method thereof according to the present invention will be specifically described by exemplifying examples that satisfy the requirements of the present invention and comparative examples that do not satisfy the requirements.
アルミニウムの高純度地金を溶解し、中間合金を添加する等して表１に示す成分のアルミニウム合金を調整して鋳造し、均質化処理、熱間圧延、冷間圧延にて、板厚１．０ｍｍのアルミニウム合金板を常法にて作製した。得られたアルミニウム合金板を、外径６６ｍｍ、内径１９ｍｍの円環形状に打ち抜き、２０枚ずつ積み付け、表１に示す条件（焼鈍温度までの加熱速度、焼鈍（保持）の温度および時間、焼鈍後の冷却速度）で積付け焼鈍して、２．５インチタイプのブランクを作製して、供試材とした。 Aluminum alloy with the components shown in Table 1 is prepared by melting high purity ingots of aluminum, adding an intermediate alloy, etc., and casted by homogenization, hot rolling, cold rolling, and plate thickness 1 A 0.0 mm aluminum alloy plate was produced by a conventional method. The obtained aluminum alloy plate was punched into an annular shape having an outer diameter of 66 mm and an inner diameter of 19 mm, stacked 20 pieces at a time, and the conditions shown in Table 1 (heating rate up to annealing temperature, annealing (holding) temperature and time, annealing Stacking annealing was performed at a later cooling rate to produce a 2.5-inch type blank as a test material.
作製した供試材について、以下の通り、平坦度の変化量を測定し、耐力を評価して、表１に示す。なお、表１のアルミニウム合金の検出限界以下の成分は「−」で表し、また、途中の工程にて不具合により中断したものは、以下の工程、ならびに測定および評価を行わず、表１の積付け焼鈍条件および測定値等の欄を「−」で表す。 About the produced test material, the variation | change_quantity of flatness is measured as follows, and yield strength is evaluated, and it shows in Table 1. In addition, the component below the detection limit of the aluminum alloy in Table 1 is represented by “−”, and those interrupted due to a defect in the middle process are not subjected to the following process, measurement and evaluation, and the product in Table 1. Columns such as an annealing condition and measured values are represented by “−”.
（平坦度の変化量）
供試材の平坦度を測定し、次に、ＦｅＰｔ系合金のスパッタリングを模擬した加熱処理として、連続焼鈍炉にて昇温速度６００℃／分で５００℃に昇温し、１０秒間加熱した後、炉外にてエアー噴射による空冷で１００℃以下に冷却した。加熱処理後、再度、平坦度を測定し、前後の平坦度の差を算出して、平坦度の変化量とした。なお、加熱処理は、開始温度を室温（２５℃）とし、この室温から前記昇温速度で昇温した。平坦度は、ＮＩＤＥＫ社製ＦＴ−１７を用いて、Ｐ−Ｖ値を測定して得た。
(Change in flatness)
After measuring the flatness of the specimen, and then heating as a heat treatment simulating the sputtering of the FePt-based alloy, the temperature was raised to 500 ° C. at a temperature rising rate of 600 ° C./min in a continuous annealing furnace, and heated for 10 seconds. Then, it was cooled to 100 ° C. or lower by air cooling by air injection outside the furnace. After the heat treatment, the flatness was measured again, and the difference between the flatness before and after was calculated as the amount of change in flatness. In the heat treatment, the starting temperature was set to room temperature (25 ° C.), and the temperature was increased from the room temperature at the rate of temperature increase. The flatness was obtained by measuring the PV value using FT-17 manufactured by NIDEK.
（耐力）
供試材を切り出してＪＩＳ５号引張試験片を作製し、ＪＩＳＺ２２４１に基づいた引張試験により耐力を測定した。合格基準は、耐力が９５ＭＰａを超えることとした。
(Strength)
The specimen was cut out to produce a JIS No. 5 tensile test piece, and the yield strength was measured by a tensile test based on JISZ2241. The acceptance criterion was that the yield strength exceeded 95 MPa.
供試材Ｎｏ．１〜１７は、アルミニウム合金の成分および積付け焼鈍条件がいずれも本発明の範囲の実施例であり、５００℃での加熱による平坦度の変化量が５μｍ以下となり、磁気ディスク用アルミニウム合金基板として十分な耐力を有していた。 Specimen No. Nos. 1 to 17 are examples in which the components of the aluminum alloy and the stacking annealing conditions both fall within the scope of the present invention, and the amount of change in flatness due to heating at 500 ° C. is 5 μm or less. It had sufficient yield strength.
これに対して、供試材Ｎｏ．１８〜２３は、アルミニウム合金の成分が本発明の範囲外の比較例である。供試材Ｎｏ．１８は、Ｍｇが不足したため、強度が不十分であった。反対に、供試材Ｎｏ．１９は、Ｍｇが過剰であるため、熱間圧延にて割れを生じた。供試材Ｎｏ．２０〜２３は、Ｃｒ，Ｍｎ，Ｚｒが過剰であるため、溶解時に溶け残り、鋳造することができなかった。 On the other hand, the test material No. 18-23 are comparative examples in which the components of the aluminum alloy are outside the scope of the present invention. Specimen No. No. 18 had insufficient strength due to lack of Mg. On the other hand, the test material No. No. 19 was cracked by hot rolling because Mg was excessive. Specimen No. In Nos. 20 to 23, Cr, Mn, and Zr were excessive, so that they remained undissolved during melting and could not be cast.
供試材Ｎｏ．２４〜３３は、アルミニウム合金の成分は本発明の範囲であるが、５００℃の加熱による平坦度の変化量が本発明の範囲外の比較例である。なお、供試材Ｎｏ．２４は供試材Ｎｏ．１１に、供試材Ｎｏ．２６〜２８は供試材Ｎｏ．４〜６に、供試材Ｎｏ．２９，３０は供試材Ｎｏ．１０，１２に、それぞれ近いアルミニウム合金の成分で形成されている。 Specimen No. 24 to 33 are comparative examples in which the amount of change in flatness due to heating at 500 ° C. is outside the scope of the present invention, although the components of the aluminum alloy are within the scope of the present invention. The test material No. 24 is a specimen No. 24. 11, specimen No. Nos. 26 to 28 are specimen Nos. 4 to 6, the test material No. Nos. 29 and 30 are specimen Nos. 10 and 12 are formed of components of aluminum alloys close to each other.
供試材Ｎｏ．２４〜２６は積付け焼鈍における焼鈍温度が低いために、供試材Ｎｏ．２７は焼鈍時間が短いために、それぞれ残留歪みを完全に除去することができなかった結果、５００℃に加熱されたことで歪みが開放されて、平坦度が大きく悪化した。供試材Ｎｏ．２８，２９は、焼鈍温度への加熱速度および焼鈍後の冷却速度が急峻であるため、熱応力を生じて内部歪みが残留した。供試材Ｎｏ．３０，３１は、加熱速度および冷却速度が急峻で、さらに焼鈍時間が短いため、内部歪みが残留した。供試材Ｎｏ．３２は加熱速度が急峻であるため、その後の焼鈍（保持）で歪みが除去されなかった。供試材Ｎｏ．３３は焼鈍温度が低く、さらに冷却速度が急峻であるため、内部歪みが残留した。 Specimen No. Nos. 24-26 are low in the annealing temperature in the stacking annealing, so that the test material Nos. As for No. 27, since the annealing time was short, the residual strain could not be completely removed. As a result, the strain was released by heating to 500 ° C., and the flatness was greatly deteriorated. Specimen No. In Nos. 28 and 29, since the heating rate to the annealing temperature and the cooling rate after annealing were steep, thermal stress was generated and internal strain remained. Specimen No. In Nos. 30 and 31, the heating rate and the cooling rate were steep and the annealing time was short, so that internal strain remained. Specimen No. In No. 32, since the heating rate was steep, distortion was not removed by subsequent annealing (holding). Specimen No. No. 33 had a low annealing temperature and a steep cooling rate, so that internal strain remained.
磁気ディスクの製造における磁性膜のスパッタリングは、４００〜５００℃の間で様々な成膜条件となる可能性がある。そこで、実施例である供試材Ｎｏ．４，７、および比較例である供試材Ｎｏ．２５，２６について、加熱処理の温度および時間を表２に示すように変化させて、平坦度の変化量を比較した。なお、実施例１の５００℃で１０秒間の加熱についても併記する。 Sputtering of a magnetic film in the manufacture of a magnetic disk may have various film forming conditions between 400 and 500 ° C. Therefore, the test material No. which is an example. Nos. 4 and 7 and Comparative Sample No. For 25 and 26, the temperature and time of the heat treatment were changed as shown in Table 2, and the amount of change in flatness was compared. In addition, it describes together about the heating for 10 second at 500 degreeC of Example 1. FIG.
表２に示すように、供試材Ｎｏ．４，７，２５，２６は、いずれも加熱温度および時間が増加するにしたがい平坦度が低下する傾向が観察された。ただし、実施例である供試材Ｎｏ．４，７は、実施例１にて測定した５００℃で１０秒間の加熱と同様に良好な平坦度を示し、特に供試材Ｎｏ．７は、平坦度の変化量が１μｍ以下と優れていた。これに対して、供試材Ｎｏ．２６は、加熱温度４００℃での平坦度の変化量は少ないが、５００℃では多くなった。さらに供試材Ｎｏ．２５は、加熱温度４００℃から平坦度が大きく低下した。 As shown in Table 2, the test material No. As for 4,7,25,26, the tendency for flatness to fall was observed as heating temperature and time increased. However, sample material No. which is an Example. Nos. 4 and 7 showed good flatness as in the case of heating at 500 ° C. for 10 seconds measured in Example 1. No. 7 was excellent with a flatness change amount of 1 μm or less. On the other hand, the test material No. No. 26 showed little change in flatness at a heating temperature of 400 ° C., but increased at 500 ° C. Furthermore, sample No. No. 25, the flatness greatly decreased from the heating temperature of 400 ° C.
以上、発明を実施するための形態および実施例を通じて本発明に係る磁気ディスク用アルミニウム合金基板およびその製造方法について詳細に説明した。しかし、本発明の趣旨はこれらの記載に限定されて解釈されるものではなく、特許請求の範囲の記載に基づいて広く解釈しなければならない。 As described above, the aluminum alloy substrate for magnetic disk and the manufacturing method thereof according to the present invention have been described in detail through the embodiments and examples for carrying out the invention. However, the gist of the present invention should not be construed as being limited to these descriptions, but should be broadly interpreted based on the descriptions in the claims.
Claims (3)
５００℃で１０秒間加熱された前後における平坦度の変化量が５μｍ以下であることを特徴とする磁気ディスク用アルミニウム合金基板。 Mg: an aluminum alloy substrate for a magnetic disk comprising 3.5% by mass or more and 6% by mass or less, the balance being an aluminum alloy composed of Al and inevitable impurities,
An aluminum alloy substrate for a magnetic disk, wherein the flatness change amount before and after being heated at 500 ° C. for 10 seconds is 5 μm or less.
前記アルミニウム合金からなるアルミニウム合金板を成形する成形工程と、前記成形したアルミニウム合金板を積付け焼鈍にて平坦化する積付け焼鈍工程と、を行い、
前記積付け焼鈍工程は、前記成形したアルミニウム合金板を、加熱速度２℃／分以下で４００℃以上に加熱して、４００℃以上で２時間以上保持した後、冷却速度２℃／分以下で２００℃以下に冷却することを特徴とする磁気ディスク用アルミニウム合金基板の製造方法。 A method of manufacturing an aluminum alloy substrate for a magnetic disk according to claim 1 or 2,
A forming step of forming an aluminum alloy plate made of the aluminum alloy, and a stacking annealing step of flattening the formed aluminum alloy plate by stacking annealing,
In the stacking annealing step, the molded aluminum alloy plate is heated to 400 ° C. or higher at a heating rate of 2 ° C./min or less and held at 400 ° C. or higher for 2 hours or more, and then at a cooling rate of 2 ° C./min or less. A method for producing an aluminum alloy substrate for a magnetic disk, characterized by cooling to 200 ° C. or lower.
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| WO2015027037A1 (en) * | 2013-08-21 | 2015-02-26 | Taheri Mitra Lenore | Annealing process |
| WO2016190277A1 (en) * | 2015-05-28 | 2016-12-01 | 株式会社Uacj | Aluminum alloy substrate for magnetic discs and manufacturing method therefor, as well as magnetic disc using said aluminum alloy substrate for magnetic discs |
| JP6990290B1 (en) | 2020-12-24 | 2022-02-03 | 株式会社Uacj | Aluminum alloy disc blanks and magnetic discs for magnetic discs |
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| JP5815153B1 (en) * | 2015-07-02 | 2015-11-17 | 株式会社神戸製鋼所 | Aluminum alloy blank for magnetic disk and aluminum alloy substrate for magnetic disk |
| US11149332B2 (en) | 2017-04-15 | 2021-10-19 | The Boeing Company | Aluminum alloy with additions of magnesium and at least one of chromium, manganese and zirconium, and method of manufacturing the same |
| JP6640958B1 (en) * | 2018-11-15 | 2020-02-05 | 株式会社神戸製鋼所 | Aluminum alloy plate for magnetic disk, aluminum alloy blank for magnetic disk and aluminum alloy substrate for magnetic disk |
| CN115233050B (en) * | 2022-08-15 | 2024-06-04 | 重庆大学 | Al-Mg-Mn-Zr-Cr alloy and preparation method thereof |
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| CN107532245A (en) * | 2015-05-28 | 2018-01-02 | 株式会社Uacj | Aluminium alloy base plate for magnetic disk and its manufacture method and the disk for having used the aluminium alloy base plate for magnetic disk |
| CN107532245B (en) * | 2015-05-28 | 2019-07-16 | 株式会社Uacj | Aluminium alloy base plate for magnetic disk and its manufacturing method and the disk for having used the aluminium alloy base plate for magnetic disk |
| US10755738B2 (en) | 2015-05-28 | 2020-08-25 | Uacj Corporation | Aluminum alloy substrate for magnetic discs and manufacturing method therefor, as well as magnetic disc using said aluminum alloy substrate for magnetic discs |
| JP6990290B1 (en) | 2020-12-24 | 2022-02-03 | 株式会社Uacj | Aluminum alloy disc blanks and magnetic discs for magnetic discs |
| WO2022138614A1 (en) * | 2020-12-24 | 2022-06-30 | 株式会社Uacj | Aluminum alloy disk blank for magnetic disk and magnetic disk |
| JP2022100921A (en) * | 2020-12-24 | 2022-07-06 | 株式会社Uacj | Aluminum alloy disk blank for magnetic disk, and magnetic disk |
| US12087342B2 (en) | 2020-12-24 | 2024-09-10 | Uacj Corporation | Aluminum alloy disc blank for magnetic disc and magnetic disc |
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