JPS63125667A - Production of thin amorphous ta-w alloy film - Google Patents

Production of thin amorphous ta-w alloy film

Info

Publication number
JPS63125667A
JPS63125667A JP27018386A JP27018386A JPS63125667A JP S63125667 A JPS63125667 A JP S63125667A JP 27018386 A JP27018386 A JP 27018386A JP 27018386 A JP27018386 A JP 27018386A JP S63125667 A JPS63125667 A JP S63125667A
Authority
JP
Japan
Prior art keywords
alloy
substrate
amorphous
thin film
vacuum
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP27018386A
Other languages
Japanese (ja)
Other versions
JPH0582465B2 (en
Inventor
Tsutomu Yoshitake
務 吉武
Yoshimi Kubo
佳実 久保
Hitoshi Igarashi
五十嵐 等
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NEC Corp filed Critical NEC Corp
Priority to JP27018386A priority Critical patent/JPS63125667A/en
Publication of JPS63125667A publication Critical patent/JPS63125667A/en
Publication of JPH0582465B2 publication Critical patent/JPH0582465B2/ja
Granted legal-status Critical Current

Links

Landscapes

  • Physical Vapour Deposition (AREA)

Abstract

PURPOSE:To easily produce a thin amorphous Ta-W alloy film having excellent mechanical properties, corrosion resistance, etc., by respectively heating a Ta-W alloy and Si to melt and evaporate in a vacuum and depositing the vapor thereof by evaporation on a cooled substrate, thereby forming the thin film expressed by the specific formula on the substrate. CONSTITUTION:The Ta-W alloy 1 and Si2 are respectively held in crucibles 3, 4 and are cooled by cooling water. The substrate 6 is provided above the same and is satisfactorily cooled by liquid nitrogen 9. After the inside of a chamber 10 is evacuated to a vacuum by a vacuum pump 11, electron beams are generated by electron beam sources 12, 13 to simultaneously heat and melt materials 1, 2 to be evaporated, by which the Ta-W alloy and Si are evaporated in the atom state and are stuck in the form of a homogenous alloy on the substrate 6. The thin amorphous Ta-W alloy film which is expressed by (Ta1-xWx)1-ySiy (x=0.01-1, y=0.1-0.4) and has a high crystallization temp. is thereby easily formed on the substrate 6.

Description

【発明の詳細な説明】 (産業上の利用分野) 本発明は高い結晶化温度を有する非晶質合金の製造方法
に関するものである。
DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing an amorphous alloy having a high crystallization temperature.

(従来の技術) 近年、各種の非晶質材料が開発され、金属材料の分野に
おいて、多くの注目を集めている。これらの合金は、従
来の結晶合金とは異なり、結晶構造を持たない合金であ
り、その性質も従来の金属材料にはみちれないものが多
く、機械的性膏、耐摩耗性、耐食性、軟磁性、電気的性
質などに優れているため、結晶質金属に代わりうる材料
として、各種の用途開発が行われ、さらに、その用途に
適した材料開発も行われている。これらの合金は、従来
、一般に、単ロール法等の液体急冷法によって作製され
ている。
(Prior Art) In recent years, various amorphous materials have been developed and are attracting a lot of attention in the field of metal materials. Unlike conventional crystalline alloys, these alloys do not have a crystalline structure, and many of their properties are not that of conventional metal materials, such as mechanical properties, wear resistance, corrosion resistance, and softness. Due to its excellent magnetic and electrical properties, various uses are being developed as a material that can replace crystalline metals, and materials suitable for these uses are also being developed. These alloys have conventionally been generally produced by a liquid quenching method such as a single roll method.

(発明が解決しようとする問題点) 非晶質合金の最大の問題点は、熱的に不安定な点にある
。これは非晶質状態が熱力学的に非平衡な準安定状態で
あるということに由来するもので、非晶質合金の宿命と
もいえることである。即ち、非晶質合金は、一般に、そ
れぞれ特有の結晶化温度を有し、その温度を越えるとよ
り熱的に安定な結晶合金に変化してしまい、非晶質状態
のときにみられた優れた諸特性が全て失われてしまうの
である。この結晶化温度は、材料によって異なるが、一
般に、絶対温度で測定した融点の0.4〜0.6倍程度
の値をとることが知られている。従って、結晶化温度の
高い合金を得るためには、融点の高い合金を非晶質化し
なければならない。
(Problems to be Solved by the Invention) The biggest problem with amorphous alloys is that they are thermally unstable. This is due to the fact that the amorphous state is a thermodynamically non-equilibrium metastable state, and can be said to be the fate of amorphous alloys. In other words, each amorphous alloy generally has its own specific crystallization temperature, and when that temperature is exceeded, it changes to a more thermally stable crystalline alloy, and the superiority seen in the amorphous state is lost. All the characteristics that were previously acquired are lost. Although this crystallization temperature varies depending on the material, it is generally known that it takes a value of about 0.4 to 0.6 times the melting point measured in absolute temperature. Therefore, in order to obtain an alloy with a high crystallization temperature, an alloy with a high melting point must be made amorphous.

Ta−8i−B合金は、融点が約2300°C以上とき
わめて高い。このため液体急冷法によって作製されたT
a −Si −B系非晶質合金は、その結晶化温度が8
00°C〜960°Cと非常に高く、非晶質合金の問題
点を大幅に改善することが可能となった(特願昭61゜
012385号)。さらに、このTa −Si −B系
非晶質合金は、一般の非晶質合金に特有の高強度、高硬
度などの優れた機械的性質を有しているために、例えば
、耐摩耗性材料、および、温度上昇を伴う電極用材料な
どへの応用が考えられる。
The Ta-8i-B alloy has an extremely high melting point of about 2300°C or higher. For this reason, T
The a-Si-B amorphous alloy has a crystallization temperature of 8
00°C to 960°C, making it possible to significantly improve the problems of amorphous alloys (Japanese Patent Application No. 61°012385). Furthermore, this Ta-Si-B-based amorphous alloy has excellent mechanical properties such as high strength and high hardness characteristic of general amorphous alloys, so it can be used as a wear-resistant material, for example. It can also be applied to materials for electrodes that are subject to temperature increases.

しかしながら、実際に前記Ta −Si −B系非晶質
合金を高温環境下で使用する場合には、経時変化が問題
となってくるために、使用温度範囲は最高600°C程
度に限定されてしまう。
However, when the Ta-Si-B amorphous alloy is actually used in a high-temperature environment, aging becomes a problem, so the operating temperature range is limited to a maximum of about 600°C. Put it away.

さらに、液体急冷法によって作製されるTa−8i−B
系非晶質合金は、その形状が幅数mm〜数cmのリボン
状であるために、広い面積を有する非晶質合金を得るこ
とができないという問題%;::” へや・1 (35ツ 点があった。さらに、ある物質の上に、前記非晶質合金
を薄膜状で形成することも、従来の液体急冷法ではでき
なかった。
Furthermore, Ta-8i-B produced by liquid quenching method
Since the amorphous alloy has a ribbon shape with a width of several mm to several cm, there is a problem that it is impossible to obtain an amorphous alloy with a wide area. Furthermore, it has not been possible to form a thin film of the amorphous alloy on a certain substance using the conventional liquid quenching method.

本発明は、このような従来技術の問題点を解決して、高
い結晶化温度を有し、がっ、機械的特性、耐食性等にす
ぐれたTa−W系非晶質合金薄膜の製造方法を提供する
ことを目的とする。
The present invention solves the problems of the prior art and provides a method for producing a Ta-W based amorphous alloy thin film that has a high crystallization temperature, excellent mechanical properties, corrosion resistance, etc. The purpose is to provide.

(問題点を解決するための手段) 本発明は、(Ta1−xWx)1−、si、、なる式で
表され、x=0.01〜1.y=0.1〜0.4である
合金を、真空中において、金属を加熱溶解し、金属原子
を蒸発させることによって、基板上に付着させ、非晶質
薄膜を形成することを特徴とするTa−W系非晶質合金
薄膜の製造方法である。
(Means for Solving the Problems) The present invention is expressed by the formula (Ta1-xWx)1-, si, where x=0.01 to 1. An alloy in which y=0.1 to 0.4 is deposited on a substrate by heating and melting the metal in a vacuum and evaporating the metal atoms to form an amorphous thin film. This is a method for producing a Ta-W based amorphous alloy thin film.

(作用) Ta −W −Si系合金では、後に実施例で示すよう
に、TaとW、またはWが60at%〜90at%の組
成範囲で、非晶質合金ができることを本発明者は見いだ
した。この組成範囲をはずれると非晶質構造がほとんど
みられなくなり、非晶質合金に特徴的な優れた特性がす
べて消失してしまう。また、Xの範囲を0.01以上と
限定したのは、この範囲に於て、Taのみの場合、およ
び、Wを微量添加した場合よりも結晶化温度が高くなる
からである。
(Function) In Ta-W-Si alloys, as shown in Examples later, the present inventors have found that an amorphous alloy can be formed in a composition range of Ta and W, or W in a range of 60 at% to 90 at%. . When the composition is outside this range, almost no amorphous structure is observed, and all the excellent properties characteristic of amorphous alloys are lost. Further, the reason why the range of X is limited to 0.01 or more is because in this range, the crystallization temperature becomes higher than when only Ta is used or when a small amount of W is added.

これらの非晶質合金の結晶化温度は、その融点の高さに
対応して、いずれも1000°C以上という高い値であ
る。また、これらの非晶質合金の機械的特性は、非晶質
合金に一般にみちれるように、高強度かつ高硬度である
。また、耐食性においても、Taのすぐれた耐食性に匹
敵するほどの耐食性を有している。
The crystallization temperatures of these amorphous alloys are all as high as 1000° C. or higher, corresponding to their high melting points. Further, the mechanical properties of these amorphous alloys are high strength and high hardness, as is generally the case with amorphous alloys. Also, in terms of corrosion resistance, it has corrosion resistance comparable to that of Ta.

本発明による製造方法は、真空中において、金属を加熱
溶解して、金属原子を蒸発させることによって、基板上
に付着させ、非晶質薄膜を形成する方法であるが、この
際、原料合金の溶解を水冷されたるつぼのなかで行うの
で、原料合金とるつぼ金属の反応はほとんどおこらない
。るつぼ金属が十分に冷却されている場合には、たとえ
高温度の溶解金属が接触したとしても、るつぼ金属の温
度が低すぎるために合金化反応が極めて起こりにくいか
らである。
The manufacturing method according to the present invention is a method in which a metal is heated and melted in a vacuum to evaporate metal atoms, thereby depositing them on a substrate to form an amorphous thin film. Since melting is carried out in a water-cooled crucible, there is almost no reaction between the raw material alloy and the crucible metal. This is because if the crucible metal is sufficiently cooled, even if high-temperature molten metal comes into contact with it, the temperature of the crucible metal is too low and alloying reactions are extremely unlikely to occur.

また、基板は、水、液体窒素等の冷媒によって、冷却し
ておく必要がある。これは、薄膜作製中の基板温度が高
すぎると、形成された合金薄膜が、結晶質になってしま
い、非晶質相が得られないからである。
Further, the substrate needs to be cooled with a coolant such as water or liquid nitrogen. This is because if the substrate temperature during thin film production is too high, the formed alloy thin film will become crystalline and an amorphous phase will not be obtained.

さらに、溶解手段としては、電子ビーム溶解、レーザー
ビーム溶解などのよく知られた方法を用いることができ
る。
Further, as the melting means, well-known methods such as electron beam melting and laser beam melting can be used.

また、溶解される原料物質としては、目的組成のTa−
W−8i合金、あるいは、Ta、 WおよびSiを別々
に準備することができる。Ta−W−8i合金の場合に
は、この合金を溶解することによって、また、Ta、 
WおよびSiを別々に準備する場合には、それぞれを同
時に別個に溶解することによって、薄膜を形成すること
ができる。また、得られる合金薄膜の組成は、原料とな
るTa −W −Si合金の組成を変化させることによ
り、また、Ta、 WおよびSiの蒸気圧を調整するこ
とにより、容易に変化させることか出来るため、目的と
する組成の非晶質合金薄膜を容易に得ることができる。
In addition, the raw material to be dissolved is Ta-
A W-8i alloy or Ta, W and Si can be prepared separately. In the case of Ta-W-8i alloy, by melting this alloy, Ta,
When W and Si are prepared separately, a thin film can be formed by separately melting each at the same time. Furthermore, the composition of the obtained alloy thin film can be easily changed by changing the composition of the Ta-W-Si alloy used as the raw material and by adjusting the vapor pressures of Ta, W, and Si. Therefore, an amorphous alloy thin film having a desired composition can be easily obtained.

以上のように、本発明の製造方法によって、Ta−W系
非晶質合金は、組成制御された、高純度の合金薄膜とし
て、大面積に、かつ、均質に、基板上に形成することが
できる。
As described above, by the manufacturing method of the present invention, a Ta-W-based amorphous alloy can be uniformly formed over a large area as a high-purity alloy thin film with controlled composition on a substrate. can.

(実施例) 以下、本発明の一実施例を図により詳細に説明する。第
1図に、本発明のTa−W系非晶質合金薄膜を作製する
装置の一例を示す。第1図に示す装置は高真空電子ビー
ム蒸着装置である。蒸発材料1゜2は、それぞれるつぼ
3,4に保持されている。本実施例においては、蒸発材
料1にはTa−W合金、また、蒸発材料2には、Siを
使用した。各蒸発材料は、るつぼ中に50g準備するこ
とができる。るつぼ3,4は銅製であり、冷却水導入管
5によって、水冷されており、蒸発材料が溶解した状態
においても、温度が上昇することはない。
(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of an apparatus for producing the Ta--W amorphous alloy thin film of the present invention. The apparatus shown in FIG. 1 is a high vacuum electron beam evaporation apparatus. Evaporated materials 1 and 2 are held in crucibles 3 and 4, respectively. In this example, the evaporation material 1 was a Ta-W alloy, and the evaporation material 2 was Si. 50 g of each evaporated material can be prepared in a crucible. The crucibles 3 and 4 are made of copper and are water-cooled by a cooling water introduction pipe 5, so that the temperature does not rise even when the evaporation material is dissolved.

基板6は、基板ホルダー7に固定されている。基板には
、長さ50mm、幅25mmで厚さ0.2mmのガラス
を用いた。基板ホルダー7には、液体窒素導入管8より
導入された液体窒素9が蓄えられており、基板が十分冷
却される構造になっている。
The substrate 6 is fixed to a substrate holder 7. The substrate used was glass with a length of 50 mm, a width of 25 mm, and a thickness of 0.2 mm. The substrate holder 7 stores liquid nitrogen 9 introduced from a liquid nitrogen introduction pipe 8, and has a structure in which the substrate is sufficiently cooled.

薄膜作製に際しては、最初に、真空チャンバー10を真
空ポンプ11によって、1O−8Torr台の真空まで
排気する。この状態で、電子ビーム源12.13より、
電子ビームを発生させ、蒸発材料1,2を同時に加熱、
溶解させる。溶解した材料からは、Ta、WおよびSi
が原子状態で蒸発する。蒸着の最初1時間は、シャッタ
ー14を閉じた状態で予備蒸着を行う。つぎに、予備蒸
着終了後、シャッターを開くことにより、基板上に薄膜
を作製した。蒸発材料1および2から飛び出した蒸発原
子は、基板付近でお互いに混合状態になり、基板に付着
する際には、均質な合金として付着する。薄膜作製中の
真空度は、1O−7Torrであった。また、薄膜作製
中の基板温度を熱電対15を通して、温度計16によっ
て測定したところ、−180°Cであった。蒸着は、1
時間行った。得られた薄膜の厚さは、5pm程度であっ
た。
When producing a thin film, first, the vacuum chamber 10 is evacuated to a vacuum level of 10-8 Torr using the vacuum pump 11. In this state, from the electron beam source 12.13,
Generate an electron beam to simultaneously heat the evaporation materials 1 and 2,
Dissolve. From the melted material, Ta, W and Si
evaporates in the atomic state. During the first hour of vapor deposition, preliminary vapor deposition is performed with the shutter 14 closed. Next, after the preliminary vapor deposition was completed, a thin film was produced on the substrate by opening the shutter. The evaporated atoms ejected from the evaporation materials 1 and 2 are mixed with each other near the substrate, and when they adhere to the substrate, they adhere as a homogeneous alloy. The degree of vacuum during thin film preparation was 10-7 Torr. Moreover, when the substrate temperature during thin film production was measured by the thermometer 16 through the thermocouple 15, it was -180°C. Vapor deposition is 1
Time went. The thickness of the obtained thin film was about 5 pm.

得られたTa −W −Si合金薄膜の構造をX線回折
法によって評価した。その結果、薄膜の組成でTaとW
およびWが60at%〜90at%の組成範囲ではいず
れの薄帯も結晶による鋭い回折ピークはみられず、ブロ
ードなハローパターンが得られたことから、非晶質合金
薄膜が得られたことが確認された。第1表に、示差熱分
析で測定したこれらの試料の結晶化温度を示す。いずれ
も1000°C以上の高い結晶化温度を示しており、T
a −Si −B系非晶質合金の場合よりもさらに10
0°C〜200°C高い結晶化温度を有していることが
わかる。また、これらの試料は、800°Cで1000
時間焼鈍した後も非晶質構造を有しており、非常に耐熱
性の高い非晶質合金であることが判明した。またこれら
の機械的特性は、ビッカース硬度が800〜1500の
範囲であるという優れた性質を示した。さらに、これら
の試料は濃塩酸、濃硝酸、濃硫酸、濃王水のr4xjこ
一日放置しても何等腐食された様子は見られず、重量変
化も認められなかった。
The structure of the obtained Ta-W-Si alloy thin film was evaluated by X-ray diffraction method. As a result, we found that the composition of the thin film is Ta and W.
In the composition range of 60 at% to 90 at% W, no sharp diffraction peaks due to crystals were observed in any of the ribbons, and a broad halo pattern was obtained, confirming that an amorphous alloy thin film was obtained. It was done. Table 1 shows the crystallization temperatures of these samples determined by differential thermal analysis. All of them show high crystallization temperatures of over 1000°C, and T
10 more than in the case of a-Si-B amorphous alloy
It can be seen that the crystallization temperature is 0°C to 200°C higher. In addition, these samples were heated at 800°C for 1000
It was found that the alloy had an amorphous structure even after time-annealing, and was an extremely heat-resistant amorphous alloy. Furthermore, these materials exhibited excellent mechanical properties with Vickers hardness ranging from 800 to 1,500. Furthermore, even after these samples were left in concentrated hydrochloric acid, concentrated nitric acid, concentrated sulfuric acid, and concentrated aqua regia for one day, no signs of corrosion were observed, and no change in weight was observed.

第1表 なお、本実施例では、高真空電子ビーム蒸着装置による
Ta−W系非晶質合金薄膜の製造方法を紹介したが、非
晶質薄膜を作製する際に、他の蒸着方法、即ち、レーザ
ービーム蒸着法、クラスターイオンビーム蒸着法等を利
用してもさしつかえない。
Table 1 Note that in this example, a method for producing a Ta-W amorphous alloy thin film using a high-vacuum electron beam evaporation apparatus was introduced, but when producing an amorphous thin film, other vapor deposition methods, such as , laser beam evaporation method, cluster ion beam evaporation method, etc. may be used.

(発明の効果) 以上詳細に説明したように、本発明によるTa−W系非
晶質合金薄膜の製造方法は高い結晶化温度を有し、かつ
、機械的特性、耐食性等にすぐれた非晶質合金薄膜が容
易に得られ、その効果は大きい。
(Effects of the Invention) As explained in detail above, the method for producing a Ta-W amorphous alloy thin film according to the present invention has a high crystallization temperature and an amorphous film with excellent mechanical properties, corrosion resistance, etc. A high quality alloy thin film can be easily obtained, and the effect is great.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図は、本発明のTa−W系非晶質合金薄膜を作製す
る装置の一例を示す図である。図において、1および2
は蒸発材料、3および4はるつぼ、5は冷却水導入管、
6は基板、7は基板ホルダー、8は液体窒素導入管、9
は液体窒素、10はチャンバー、11は真空ポンプ、1
2および13は電子ビーム源、14はj・) 第1図
FIG. 1 is a diagram showing an example of an apparatus for producing a Ta-W based amorphous alloy thin film of the present invention. In the figure, 1 and 2
is an evaporation material, 3 and 4 are crucibles, 5 is a cooling water introduction pipe,
6 is a substrate, 7 is a substrate holder, 8 is a liquid nitrogen introduction tube, 9
is liquid nitrogen, 10 is a chamber, 11 is a vacuum pump, 1
2 and 13 are electron beam sources, 14 is j・) Figure 1

Claims (1)

【特許請求の範囲】 (Ta_1_−_xW_x)_1_−_ySi_yなる
式で表され、x=0.01〜1、y=0.1〜0.4で
ある組成の合金を、真空中において、金属を加熱溶解し
、金属原子を蒸発させることによって、基板上に薄膜を
形成する真空蒸着装置を用いて、非晶質化させることを
特徴とする Ta−W系非晶質合金薄膜の製造方法。
[Scope of Claims] An alloy represented by the formula (Ta_1_-_xW_x)_1_-_ySi_y with a composition of x=0.01 to 1 and y=0.1 to 0.4 is made of metal in a vacuum. 1. A method for producing a Ta--W amorphous alloy thin film, which is characterized in that it is made amorphous using a vacuum evaporation device that forms a thin film on a substrate by heating and melting and evaporating metal atoms.
JP27018386A 1986-11-12 1986-11-12 Production of thin amorphous ta-w alloy film Granted JPS63125667A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP27018386A JPS63125667A (en) 1986-11-12 1986-11-12 Production of thin amorphous ta-w alloy film

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP27018386A JPS63125667A (en) 1986-11-12 1986-11-12 Production of thin amorphous ta-w alloy film

Publications (2)

Publication Number Publication Date
JPS63125667A true JPS63125667A (en) 1988-05-28
JPH0582465B2 JPH0582465B2 (en) 1993-11-19

Family

ID=17482679

Family Applications (1)

Application Number Title Priority Date Filing Date
JP27018386A Granted JPS63125667A (en) 1986-11-12 1986-11-12 Production of thin amorphous ta-w alloy film

Country Status (1)

Country Link
JP (1) JPS63125667A (en)

Also Published As

Publication number Publication date
JPH0582465B2 (en) 1993-11-19

Similar Documents

Publication Publication Date Title
EP0553228B1 (en) Vapour deposition apparatus and method
Chen et al. Crystallization temperature and activation energy of rf-sputtered near-equiatomic TiNi and Ti50Ni40Cu10 thin films
US4172718A (en) Ta-containing amorphous alloy layers and process for producing the same
JPH05214521A (en) Titanium sputtering target
JPS63125667A (en) Production of thin amorphous ta-w alloy film
JPS63125669A (en) Production of thin amorphous ta-w alloy film
JPS63125668A (en) Production of thin amorphous ta-w alloy film
JPS63125666A (en) Production of thin amorphous ta alloy film
JPS63130768A (en) Production of thin ta amorphous alloy film
JPS63130766A (en) Production of thin ta amorphous alloy film
JPS63125665A (en) Production of thin amorphous ta-w alloy film
JPS63125663A (en) Production of thin amorphous ta-w alloy film
JPS63125664A (en) Production of thin amorphous ta alloy film
JPH0578194A (en) Preparation of graphite crystal
JPH0448860B2 (en)
JPH0448861B2 (en)
JPS63125670A (en) Production of thin amorphous ta-w alloy film
JPH02228434A (en) Manufacture of hydrogen storage alloy
JPH0558056B2 (en)
JPH03173832A (en) Preparation of charge transfer complex
KR100548904B1 (en) Method and apparatus for producing resistance-heated boat for metal evaporation
Pelleg et al. Fabrication
Marchal et al. THE CRYSTALLIZATION OF Fe-Au AMORPHOUS ALLOYS
JPS6362839A (en) Ta-w amorphous alloy and its production
JPH01104766A (en) Sputtering target for optical recording medium

Legal Events

Date Code Title Description
EXPY Cancellation because of completion of term