JP6810939B2 - Cu-Sn-Si based superelastic alloy and its manufacturing method - Google Patents

Cu-Sn-Si based superelastic alloy and its manufacturing method Download PDF

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JP6810939B2
JP6810939B2 JP2018055326A JP2018055326A JP6810939B2 JP 6810939 B2 JP6810939 B2 JP 6810939B2 JP 2018055326 A JP2018055326 A JP 2018055326A JP 2018055326 A JP2018055326 A JP 2018055326A JP 6810939 B2 JP6810939 B2 JP 6810939B2
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真帆人 竹田
真帆人 竹田
大亮 金子
大亮 金子
村松 尚国
尚国 村松
崇成 中島
崇成 中島
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NGK Insulators Ltd
Yokohama National University NUC
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Description

本発明は、Cu−Sn−Si系超弾性合金及びその製造方法に関する。 The present invention relates to a Cu—Sn—Si based superelastic alloy and a method for producing the same.

従来から、形状記憶特性を有する合金として、Ni−Ti系合金、Cu−Sn系合金、Cu−Zn−Al系合金、Cu−Zn−Sn系合金、Cu−Al−Ni系合金、Cu−Al−Mn系合金等の様々な合金が知られている(例えば非特許文献1及び2を参照)。中でも、Ni−Ti系合金は、優れた形状記憶効果(SME)及び超弾性効果を示し、繰り返し寿命の点でも優れており、実用化が進んでいる。しかし、Ni−Ti系合金はTiを多量に含むため高価であるという問題がある。 Conventionally, as alloys having shape memory characteristics, Ni—Ti alloys, Cu—Sn alloys, Cu—Zn—Al alloys, Cu—Zn—Sn alloys, Cu—Al—Ni alloys, Cu—Al Various alloys such as −Mn alloys are known (see, for example, Non-Patent Documents 1 and 2). Among them, Ni—Ti alloys show excellent shape memory effect (SME) and superelastic effect, and are also excellent in terms of repeat life, and are being put into practical use. However, Ni—Ti alloys have the problem of being expensive because they contain a large amount of Ti.

一方、Cu−Sn系合金、Cu−Zn−Al系合金、Cu−Zn−Sn系合金、Cu−Al−Ni系合金、Cu−Al−Mn系合金等の銅合金は、Tiを含まないことから安価な原料で製造可能である。これらの銅系の形状記憶合金は、高温で安定なβ相(bccに関連する結晶構造を有する相)と呼ばれる母相を有し、この母相は合金元素が規則的な配列を有している。このβ相を急冷して準安定な状態で常温近辺とし更に冷却するとマルテンサイト変態を生じ、結晶構造が瞬時に変化する。合金は該マルテンサイト変態に起因して形状記憶効果ないし超弾性効果を呈する。しかしながら、上述したような銅合金は原料が安価であるがNi−Ti系合金ほど形状回復率が高くない。例えば、Cu−Sn系合金は外力による変形に対する回復率が小さく、強度も低い上、常温付近の比較的低温で放置すると変態温度が大幅に変わる等、特性の経時変化が大きいため、基礎的な研究以外に実用化への取り組みはされていない。 On the other hand, copper alloys such as Cu-Sn-based alloys, Cu-Zn-Al-based alloys, Cu-Zn-Sn-based alloys, Cu-Al-Ni-based alloys, and Cu-Al-Mn-based alloys should not contain Ti. It can be manufactured with inexpensive raw materials. These copper-based shape memory alloys have a matrix phase called a β phase (a phase having a crystal structure related to bcc) that is stable at high temperatures, and this matrix phase has a regular arrangement of alloying elements. There is. When this β phase is rapidly cooled to a metastable state near room temperature and further cooled, martensitic transformation occurs and the crystal structure changes instantly. The alloy exhibits a shape memory effect or a superelastic effect due to the martensitic transformation. However, although the raw materials of copper alloys as described above are inexpensive, the shape recovery rate is not as high as that of Ni—Ti alloys. For example, Cu—Sn-based alloys have a small recovery rate against deformation due to external force, low strength, and the transformation temperature changes significantly when left at a relatively low temperature near room temperature. No efforts have been made to put it into practical use other than research.

ところで、約500〜700℃の高温度域で逆変態する、応力誘起マルテンサイト変態を示す銅合金も提案されている。例えば、特許文献1(国際公開第2017/164395号)には、基本合金組成がCu100−(x+y)SnMn(式中、8≦x≦16及び2≦y≦10である)であり、Mnが固溶したβCuSn相を主相とし、該βCuSn相が熱処理あるいは加工によりマルテンサイト変態する、銅合金が開示されている。また、特許文献2(国際公開第2017/164396号)には、基本合金組成がCu100−(x+y)SnAl(式中、8≦x≦12及び8≦y≦9である)であり、Alが固溶したβCuSn相を主相とし、該βCuSn相が熱処理あるいは加工によりマルテンサイト変態する、銅合金が開示されている。これらの銅合金は、外力による変形に対して500〜800℃といった高温度域で高い回復率を示す。 By the way, a copper alloy exhibiting stress-induced martensitic transformation, which undergoes reverse transformation in a high temperature range of about 500 to 700 ° C., has also been proposed. For example, in Patent Document 1 (International Publication No. 2017/16435), the basic alloy composition is Cu 100- (x + y) Sn x Mn y (8 ≦ x ≦ 16 and 2 ≦ y ≦ 10 in the formula). There is disclosed a copper alloy in which the βCuSn phase in which Mn is dissolved is the main phase, and the βCuSn phase is transformed into martensitic transformation by heat treatment or processing. Further, in Patent Document 2 is (WO 2017/164396), (wherein, a 8 ≦ x ≦ 12 and 8 ≦ y ≦ 9) basic alloy composition Cu 100- (x + y) Sn x Al y There is disclosed a copper alloy having a βCuSn phase in which Al is dissolved as a main phase, and the βCuSn phase undergoing martensitic transformation by heat treatment or processing. These copper alloys show a high recovery rate in a high temperature range of 500 to 800 ° C. against deformation due to an external force.

国際公開第2017/164395号International Publication No. 2017/1643495 国際公開第2017/164396号International Publication No. 2017/1643496

田部井和彦著、「銅系形状記憶合金の材料特性と応用」、繊維機械学会誌、Vol.42, No.11 (1989), pp.587-593Kazuhiko Tabei, "Material Properties and Applications of Copper Shape Memory Alloys", Journal of Textile Machinery Society, Vol.42, No.11 (1989), pp.587-593 C. M. Wayman著、唯木次男訳、「形状記憶合金の応用(Some Applications of Shape Memory Alloys)」、金属学会会報, 19 (1980), pp.323-332C. M. Wayman, Translated by Tsuguo Yuiki, "Some Applications of Shape Memory Alloys", Bulletin of the Institute of Metals, 19 (1980), pp.323-332

しかしながら、特許文献1及び2に開示される銅合金は、常温での形状回復性の向上を狙ったものではなく、メガネフレーム、巻爪矯正クリップ、外反母指矯正器具等の常温で用いられる形状記憶製品には適したものではない。そこで、安価な原料で製造可能であり、外力による変形に対して常温で高い形状回復性を示す、高強度の超弾性合金が望まれる。 However, the copper alloys disclosed in Patent Documents 1 and 2 are not intended to improve shape recovery at room temperature, and are used at room temperature for eyeglass frames, ingrown nail correction clips, valgus thumb correction devices, and the like. Not suitable for shape memory products. Therefore, a high-strength superelastic alloy that can be manufactured with an inexpensive raw material and exhibits high shape recovery at room temperature against deformation due to an external force is desired.

本発明者らは、今般、安価な原料であるCu、Sn及びSiを所定の組成で合金化してβ相単相とすることにより、外力による変形に対して常温で高い形状回復性を示す、高強度の超弾性合金を提供できるとの知見を得た。 The present inventors have recently alloyed inexpensive raw materials Cu, Sn and Si with a predetermined composition to form a β-phase single phase, thereby exhibiting high shape recovery at room temperature against deformation due to an external force. We have obtained the finding that we can provide high-strength superelastic alloys.

したがって、本発明の目的は、安価な原料で製造可能であり、外力による変形に対して常温で高い形状回復性を示す、高強度の超弾性合金を提供することにある。 Therefore, an object of the present invention is to provide a high-strength superelastic alloy that can be produced with an inexpensive raw material and exhibits high shape recovery at room temperature against deformation due to an external force.

本発明の一態様によれば、Sn:9.0〜15.0at%及びSi:0.1〜5.1at%を含有し、残部がCu及び不可避不純物である、β相単相からなる、Cu−Sn−Si系超弾性合金が提供される。 According to one aspect of the present invention, it is composed of a β-phase single phase containing Sn: 9.0 to 15.0 at% and Si: 0.1 to 5.1 at%, and the balance is Cu and unavoidable impurities. Cu-Sn-Si based superelastic alloys are provided.

本発明の他の一態様によれば、前記Cu−Sn−Si系超弾性合金の製造方法であって、
Sn:9.0〜15.0at%及びSi:0.1〜5.1at%を含有し、残部がCu及び不可避不純物である原料を溶解鋳造して、鋳造材を得る工程と、
前記鋳造材を均質化処理してβ相単相を形成させる工程と、
を含む、Cu−Sn−Si系超弾性合金の製造方法が提供される。
According to another aspect of the present invention, the method for producing a Cu—Sn—Si based superelastic alloy.
A step of obtaining a cast material by melting and casting a raw material containing Sn: 9.0 to 15.0 at% and Si: 0.1 to 5.1 at% and the balance being Cu and unavoidable impurities.
A step of homogenizing the cast material to form a β-phase single-phase,
A method for producing a Cu—Sn—Si based superelastic alloy including the above is provided.

統合型熱力学計算システム(Thermo−Calc)により得られたCu−Sn−Si合金の3元系相平衡状態図である。It is a ternary phase equilibrium state diagram of the Cu-Sn-Si alloy obtained by the integrated thermodynamic calculation system (Thermo-Calc). 均質化処理後に水冷したCu−12.6Sn−2.1Si合金(例1)の応力−歪み曲線を示す図である。It is a figure which shows the stress-strain curve of the Cu-12.6Sn-2.1Si alloy (Example 1) which was water-cooled after the homogenization treatment. 均質化処理後に油冷したCu−12.6Sn−2.1Si合金(例2)の応力−歪み曲線を示す図である。It is a figure which shows the stress-strain curve of the Cu-12.6Sn-2.1Si alloy (Example 2) which was oil-cooled after the homogenization treatment. 均質化処理後に水冷したCu−9.8Sn−4.5Si合金(例3)の応力−歪み曲線を示す図である。It is a figure which shows the stress-strain curve of the Cu-9.8Sn-4.5Si alloy (Example 3) which was water-cooled after the homogenization treatment. 均質化処理後に油冷したCu−9.8Sn−4.5Si合金(例4)の応力−歪み曲線を示す図である。It is a figure which shows the stress-strain curve of the Cu-9.8Sn-4.5Si alloy (Example 4) which was oil-cooled after the homogenization treatment. 均質化処理後に水冷したCu−8.8Sn−5.7Si合金(例5)の応力−歪み曲線を示す図である。It is a figure which shows the stress-strain curve of the Cu-8.8Sn-5.7Si alloy (Example 5) which was water-cooled after the homogenization treatment. 均質化処理後に油冷したCu−8.8Sn−5.7Si合金(例6)の応力−歪み曲線を示す図である。It is a figure which shows the stress-strain curve of the Cu-8.8Sn-5.7Si alloy (Example 6) which was oil-cooled after the homogenization treatment. 均質化処理後に水冷したCu−14.3Sn合金(例7)の応力−歪み曲線を示す図である。It is a figure which shows the stress-strain curve of the Cu-14.3 Sn alloy (Example 7) which was water-cooled after the homogenization treatment. 均質化処理後に水冷した、Cu−12.6Sn−2.1Si合金(例1)、Cu−9.8Sn−4.5Si合金(例3)及びCu−8.8Sn−5.7Si合金(例5)のXRDプロファイルを示す図である。Cu-12.6Sn-2.1Si alloy (Example 1), Cu-9.8Sn-4.5Si alloy (Example 3) and Cu-8.8Sn-5.7Si alloy (Example 5), which were water-cooled after the homogenization treatment. It is a figure which shows the XRD profile of). 均質化処理後に水冷したCu−12.6Sn−2.1Si合金(例1)及び均質化処理後に油冷したCu−12.6Sn−2.1Si合金(例2)のXRDプロファイルを示す図である。It is a figure which shows the XRD profile of the Cu-12.6Sn-2.1Si alloy (Example 1) which was water-cooled after the homogenization treatment, and the Cu-12.6Sn-2.1Si alloy (Example 2) which was oil-cooled after the homogenization treatment. ..

Cu−Sn−Si系超弾性合金
本発明のCu−Sn−Si系超弾性合金は、β相単相からなる。そして、このβ相単相は、Sn:9.0〜15.0at%及びSi:0.1〜5.1at%を含有し、残部がCu及び不可避不純物である。別の表現をすれば、この合金ないしβ相は、不可避不純物を除いた基本合金組成が原子数比でCu100−(x+y)SnSi(式中、9.0≦x≦15.0及び0.1≦y≦5.1である)である。このように安価な原料であるCu、Sn及びSiを所定の組成で合金化してβ相単相とすることにより、外力による変形に対して常温で高い形状回復性を示す、高強度の超弾性合金を提供することができる。
Cu-Sn-Si-based superelastic alloy The Cu-Sn-Si-based superelastic alloy of the present invention comprises a β-phase single phase. The β-phase single-phase contains Sn: 9.0 to 15.0 at% and Si: 0.1 to 5.1 at%, and the balance is Cu and unavoidable impurities. Stated differently, the alloy to β phase during Cu 100- (x + y) Sn x Si y ( wherein the basic alloy composition except for the unavoidable impurities in atomic ratio, 9.0 ≦ x ≦ 15.0 And 0.1 ≦ y ≦ 5.1). By alloying Cu, Sn, and Si, which are inexpensive raw materials, with a predetermined composition to form a β-phase single phase, high-strength superelasticity that exhibits high shape recovery at room temperature against deformation due to external force. Alloys can be provided.

Siは、本発明のCu−Sn−Si系超弾性合金において、塑性変形を抑制する機能をもたらす。本発明の超弾性合金におけるSi含有量は0.1〜5.1at%であり、好ましくは0.1〜4.1at%であり、さらに好ましくは1.1〜3.1at%、特に好ましくは1.6〜2.6at%、例えば2.1at%である。このようなSi含有量であると、β相単相が形成しやすく、その結果、常温での高い形状回復性を実現しやすくなる。また、残部としてのCu量が多くなるので、十分な導電率も確保することができる。 Si provides a function of suppressing plastic deformation in the Cu—Sn—Si-based superelastic alloy of the present invention. The Si content in the superelastic alloy of the present invention is 0.1 to 5.1 at%, preferably 0.1 to 4.1 at%, more preferably 1.1 to 3.1 at%, and particularly preferably 1.1 to 3.1 at%. It is 1.6 to 2.6 at%, for example 2.1 at%. With such a Si content, a β-phase single-phase is likely to be formed, and as a result, high shape recovery at room temperature is likely to be realized. In addition, since the amount of Cu as the balance increases, sufficient conductivity can be ensured.

Snは、Cuとともに母相であるβCuSn相を形成することで形状記憶効果に寄与する。本発明の超弾性合金におけるSn含有量は9.0〜15.0at%であり、好ましくは10.6〜14.6at%であり、さらに好ましくは11.6〜13.6at%、特に好ましくは12.1〜13.1at%、例えば12.6at%である。このようなSn含有量であると、β相単相が形成しやすく、その結果、常温での高い形状回復性を実現しやすくなる。また、残部としてのCu量が多くなるので、十分な導電率も確保することができる。 Sn contributes to the shape memory effect by forming a βCuSn phase, which is a matrix phase, together with Cu. The Sn content in the superelastic alloy of the present invention is 9.0 to 15.0 at%, preferably 10.6 to 14.6 at%, more preferably 11.6 to 13.6 at%, and particularly preferably 11.6 to 13.6 at%. It is 12.1 to 13.1 at%, for example, 12.6 at%. With such a Sn content, a β-phase single-phase is likely to be formed, and as a result, high shape recovery at room temperature is likely to be realized. In addition, since the amount of Cu as the balance increases, sufficient conductivity can be ensured.

したがって、本発明のCu−Sn−Si系超弾性合金は、Sn含有量が12.6at%であり、かつ、Si含有量が2.1at%であるのが特に好ましい。すなわち、不可避不純物を除いた基本合金組成が原子数比でCu85.3Sn12.6Si2.1であるのが特に好ましい。 Therefore, the Cu—Sn—Si-based superelastic alloy of the present invention preferably has a Sn content of 12.6 at% and a Si content of 2.1 at%. That is, it is particularly preferable that the basic alloy composition excluding unavoidable impurities is Cu 85.3 Sn 12.6 Si 2.1 in terms of atomic number ratio.

本発明のCu−Sn−Si系超弾性合金は残部としてCu及び不可避不純物を含む。すなわち、本発明の超弾性合金はTiを含まない銅合金であり、それ故、高価なTiを多量に含むNi−Ti系合金よりも格段に安価な原料で製造することができる。不可避不純物の例としては、Fe、Pb、Bi、Cd、Sb、S、As、Se及びTeが挙げられる。不可避不純物の量は合計で0.5at%以下であることが好ましく、0.2at%以下がより好ましく、0.1at%以下がさらに好ましい。 The Cu-Sn-Si-based superelastic alloy of the present invention contains Cu and unavoidable impurities as a balance. That is, the superelastic alloy of the present invention is a Ti-free copper alloy, and therefore can be produced from a much cheaper raw material than a Ni—Ti alloy containing a large amount of expensive Ti. Examples of unavoidable impurities include Fe, Pb, Bi, Cd, Sb, S, As, Se and Te. The total amount of unavoidable impurities is preferably 0.5 at% or less, more preferably 0.2 at% or less, still more preferably 0.1 at% or less.

本発明のCu−Sn−Si系超弾性合金は、β相単相からなる。この場合、β相単相は、Siが固溶したCu−Sn合金のβ相単相であるといえる。したがって、本発明のCu−Sn−Si系超弾性合金は、α相、δ相、ε相等の異相、又は他の成分を含まないことが望まれる。これらの異相の有無は、後述する実施例で述べるようなX線回折においてα相、δ相、ε相等の異相に由来するピークが検出されるか否かで決定することができる。もっとも、本発明によるCu−Sn−Si系超弾性合金のβ相由来の特性を劣化させない程度において、微量の異相又は他の成分を含んでいてもよい。 The Cu—Sn—Si-based superelastic alloy of the present invention comprises a β-phase single-phase. In this case, the β-phase single phase can be said to be the β-phase single phase of the Cu—Sn alloy in which Si is solid-solved. Therefore, it is desired that the Cu—Sn—Si based superelastic alloy of the present invention does not contain different phases such as α phase, δ phase and ε phase, or other components. The presence or absence of these different phases can be determined by whether or not peaks derived from different phases such as α phase, δ phase, and ε phase are detected in X-ray diffraction as described in Examples described later. However, a trace amount of different phase or other components may be contained to the extent that the characteristics derived from the β phase of the Cu—Sn—Si superelastic alloy according to the present invention are not deteriorated.

本発明のCu−Sn−Si系超弾性合金は、常温(室温ともいう、例えば25℃)で超弾性効果を呈することが可能である。例えば、後述する実施例で述べる3点曲げ試験において残留歪みが好ましくは2.0%以下、より好ましくは0.5%以下になるレベルの形状回復性を示す場合、超弾性効果を呈するとみなすことができる。 The Cu—Sn—Si-based superelastic alloy of the present invention can exhibit a superelastic effect at room temperature (also referred to as room temperature, for example, 25 ° C.). For example, in the three-point bending test described in Examples described later, when the residual strain shows a level of shape recovery of preferably 2.0% or less, more preferably 0.5% or less, it is considered to exhibit a superelastic effect. be able to.

製造方法
本発明のCu−Sn−Si系超弾性合金は、以下に説明するように、溶解鋳造工程及び均質化工程を順次行うことにより製造することができる。
Manufacturing Method The Cu—Sn—Si-based superelastic alloy of the present invention can be manufactured by sequentially performing a melt casting step and a homogenization step as described below.

(1)溶解鋳造工程
まず、上述したCu−Sn−Si系超弾性合金の組成を与える原料を溶解鋳造して鋳造材を得る。すなわち、原料として、Sn:9.0〜15.0at%及びSi:0.1〜5.1at%を含有し、残部がCu及び不可避不純物である原料、別の表現をすれば、不可避不純物を除いた基本合金組成が原子数比でCu100−(x+y)SnSi(式中、9.0≦x≦15.0及び0.1≦y≦5.1である)である原料を調合して用いればよい。Cu、Sn及びSiを含む原料は、Cu、Sn、Siの少なくともいずれかの金属単体を含むものであってもよいし、これらのうちの2種以上の合金を含むものであってもよい。原料の配合比は所望の合金組成に合わせて調整すればよい。溶解方法は特に限定されないが、高周波溶解法が高効率な点から好ましい。また、溶解方法は、工業的利用が可能な方法で酸化抑制がなされるのが好ましい。例えば、鋳造工程は、鋳造材の酸化を抑制すべく、窒素、Ar、真空等の不活性雰囲気下で行うのが好ましい。
(1) Melt-casting step First, a raw material giving the composition of the above-mentioned Cu—Sn—Si-based superelastic alloy is melt-cast to obtain a cast material. That is, as a raw material, a raw material containing Sn: 9.0 to 15.0 at% and Si: 0.1 to 5.1 at%, and the balance being Cu and unavoidable impurities, in other words, unavoidable impurities. (wherein, 9.0 ≦ x ≦ 15.0 and a 0.1 ≦ y ≦ 5.1) except the Cu 100- (x + y) basic alloy composition in atomic ratio Sn x Si y raw material is It may be mixed and used. The raw material containing Cu, Sn and Si may contain at least one metal simple substance of Cu, Sn and Si, or may contain an alloy of two or more of these. The blending ratio of the raw materials may be adjusted according to the desired alloy composition. The dissolution method is not particularly limited, but the high-frequency dissolution method is preferable from the viewpoint of high efficiency. Further, as the dissolution method, it is preferable that oxidation is suppressed by a method that can be industrially used. For example, the casting step is preferably carried out in an inert atmosphere such as nitrogen, Ar, or vacuum in order to suppress oxidation of the casting material.

溶解鋳造においては、800〜1300℃の温度で原料を溶解させた後、該原料を800℃から400℃までの間を50〜500℃/秒の冷却速度で冷却するのが好ましい。冷却速度は、上記範囲内で可能な限り速い方が安定的なβ相を得る上で好ましい。冷却方法の例としては、空冷、油冷、水冷等が挙げられ、好ましくは水冷である。 In melt casting, it is preferable to melt the raw material at a temperature of 800 to 1300 ° C. and then cool the raw material between 800 ° C. and 400 ° C. at a cooling rate of 50 to 500 ° C./sec. It is preferable that the cooling rate is as fast as possible within the above range in order to obtain a stable β phase. Examples of the cooling method include air cooling, oil cooling, water cooling and the like, and water cooling is preferable.

(2)均質化工程
次に、鋳造材を均質化処理してβ相単相を形成させる。均質化処理は、鋳造材をβ相単相を形成可能な均質化温度で保持して均質化材を得ることにより行えばよい。均質化温度は、β相単相が安定的に析出する温度であれば特に限定されないが、典型的には650〜750℃であり、より典型的には680〜720℃である。加熱方法は特に限定されない。均質化時間は、好ましくは20分〜48時間であり、より好ましくは30分〜24時間である。均質化工程は、均質化材の酸化を抑制すべく、窒素、Ar、真空等の不活性雰囲気下で行うのが好ましい。
(2) Homogenization step Next, the cast material is homogenized to form a β-phase single phase. The homogenization treatment may be carried out by holding the cast material at a homogenization temperature capable of forming a β-phase single phase to obtain a homogenized material. The homogenization temperature is not particularly limited as long as it is a temperature at which the β-phase single phase is stably precipitated, but is typically 650 to 750 ° C., and more typically 680 to 720 ° C. The heating method is not particularly limited. The homogenization time is preferably 20 minutes to 48 hours, more preferably 30 minutes to 24 hours. The homogenization step is preferably carried out in an inert atmosphere such as nitrogen, Ar or vacuum in order to suppress the oxidation of the homogenizing material.

均質化工程においては、鋳造材を上記均質化温度に保持した後、該鋳造材を水冷により急冷するのが好ましく、より好ましくは氷水で急冷される。したがって、冷却速度は、(油冷や空冷ではなく)水冷で実現できる程度に速いことが望まれ、好ましくは10〜1000℃/秒、より好ましくは100〜1000℃/秒である。このように急冷することで、母相βCuSn単相にSiが固溶されたβ相単相の組織を生成することができる。上記のように水冷又はそれに準ずる冷却速度で急冷することで、均質化材におけるα相、δ相ないしε相の析出を回避してβ相単相を生成しやすくなるととともに、均質化材が脆くなりにくくなり加工性が向上する。また、工業的利用が可能な大きさのインゴットを鋳造する際に、インゴット内部と外部との冷却速度差が生じて不均質な組織となることも回避できる。 In the homogenization step, after the casting material is maintained at the homogenization temperature, the casting material is preferably rapidly cooled by water cooling, more preferably by ice water. Therefore, the cooling rate is desired to be fast enough to be achieved by water cooling (rather than oil cooling or air cooling), preferably 10 to 1000 ° C / sec, more preferably 100 to 1000 ° C / sec. By quenching in this way, a β-phase single-phase structure in which Si is solid-solved in the parent phase βCuSn single phase can be formed. By quenching with water cooling or a cooling rate equivalent to that as described above, it becomes easier to form a β phase single phase by avoiding the precipitation of α phase, δ phase or ε phase in the homogenizing material, and the homogenizing material becomes brittle. It becomes difficult to become difficult and workability is improved. Further, when casting an ingot having a size that can be used industrially, it is possible to avoid a heterogeneous structure due to a difference in cooling rate between the inside and the outside of the ingot.

本発明を以下の例によってさらに具体的に説明する。なお、以下の説明において、Cu−xSn−ySi(式中、x及びyは任意の数である)なる組成表記は、Sn及びSiの各係数が各元素のat%を意味し、Cuが残部であることを意味する、すなわち原子比でCu100−x−ySnSiなる組成を意味するものとする。 The present invention will be described in more detail with reference to the following examples. In the following description, the composition notation of Cu-xSn-ySi (x and y are arbitrary numbers in the formula) means that each coefficient of Sn and Si means at% of each element, and Cu is the balance. means that it is, that is intended to mean the Cu 100-x-y Sn x Si y a composition in terms of atomic ratio.

例1
Cu−Sn−Si系合金を以下の手順により作製し、評価した。
Example 1
A Cu—Sn—Si based alloy was prepared and evaluated by the following procedure.

(1)目標組成の決定
統合型熱力学計算システム(Thermo−Calc)を使用して、図1に示されるCu−Sn−Si合金の3元系相平衡状態図を計算的に作成した。Thermo−Calcは、CALPHAD法に基づく計算により相平衡状態図を作成するソフトであり、データベース上の実験パラメータを最小限使用して正則溶体近似を行うことで、ギブスエネルギー、組成及び温度の関係を導き、相平衡状態図を描くものである。得られた相平衡状態図を参照し、Cu−Sn−Si試料の700℃(973K)での構成相がβ相単相となる、Cu−12.6Sn−2.1Siを目標組成とした。
(1) Determination of target composition Using an integrated thermodynamic calculation system (Thermo-Calc), a ternary phase equilibrium diagram of the Cu—Sn—Si alloy shown in FIG. 1 was computationally prepared. Thermo-Calc is a software that creates a phase equilibrium diagram by calculation based on the CALPHAD method, and by performing a regular solution approximation using the minimum experimental parameters on the database, the relationship between Gibbs energy, composition and temperature can be determined. It guides and draws a phase equilibrium diagram. With reference to the obtained phase equilibrium diagram, the target composition was Cu-12.6Sn-2.1Si, in which the constituent phase of the Cu-Sn-Si sample at 700 ° C. (973K) was a β-phase single phase.

(2)試料作製
純Cu、純Sn及びCu−Si母合金を目標組成となるように秤量し、大気用高周波溶解炉でArガスを噴射しながら溶解鋳造した。溶解鋳造においては、1000〜1300℃の温度で原料を溶解させた後、該原料を800℃から400℃までの間を50〜500℃/秒の冷却速度で冷却した。こうして得られた試料を石英管に真空封入し、マッフル炉を用いて700℃(973K)で30分間保持することで、均質化処理(凝固による試料の鋳造組織を除去して試料を均質化する処理)を行った後、試料を氷水で急冷(水冷)した。水冷の冷却速度は500℃/秒程度と推定された。
(2) Sample preparation Pure Cu, pure Sn and Cu—Si mother alloy were weighed so as to have the target composition, and melt-cast while injecting Ar gas in a high-frequency melting furnace for the atmosphere. In melt casting, the raw material was melted at a temperature of 1000 to 1300 ° C., and then the raw material was cooled between 800 ° C. and 400 ° C. at a cooling rate of 50 to 500 ° C./sec. The sample thus obtained is vacuum-sealed in a quartz tube and held at 700 ° C. (973K) for 30 minutes using a muffle furnace to homogenize the sample by removing the cast structure of the sample by solidification. After the treatment), the sample was rapidly cooled (water-cooled) with ice water. The cooling rate of water cooling was estimated to be about 500 ° C./sec.

(3)各種評価
得られた合金試料に対して以下の評価を行った。
(3) Various evaluations The following evaluations were performed on the obtained alloy samples.

<X線回折(XRD)>
合金試料の構成相を同定するため、X線回折装置(株式会社リガク製、SmartLab)にて、管球:Cu、管電圧:40kV、管電流:50mA、測定範囲:10−90°、サンプリング幅:0.01°、測定速度:40°/分、入射スリット角度:1/3°、受光スリット1:20.0mm、及び受光スリット2:20.1mmの測定条件で試料をXRD解析して、図9及び10に示されるXRDプロファイルを得た。得られたXRDプロファイルにおいて、2θ=42°、61°及び77°の位置にβ相に由来する計3つのピークが検出される一方、上記3つのピーク以外のピーク(例えばα相、δ相、ε相等の異相に由来するピーク)は検出されなかった。このことから、本例の合金試料は表1に記されるとおりβ相単相であると同定された。
<X-ray diffraction (XRD)>
In order to identify the constituent phases of the alloy sample, an X-ray diffractometer (SmartLab, manufactured by Rigaku Co., Ltd.) was used to tube: Cu, tube voltage: 40 kV, tube current: 50 mA, measurement range: 10-90 °, sampling width. XRD analysis of the sample under the measurement conditions of 0.01 °, measurement speed: 40 ° / min, incident slit angle: 1/3 °, light receiving slit 1: 20.0 mm, and light receiving slit 2: 20.1 mm. The XRD profiles shown in FIGS. 9 and 10 were obtained. In the obtained XRD profile, a total of three peaks derived from the β phase are detected at the positions of 2θ = 42 °, 61 ° and 77 °, while peaks other than the above three peaks (for example, α phase, δ phase, etc.) are detected. Peaks derived from different phases such as ε phase) were not detected. From this, the alloy sample of this example was identified as β-phase single-phase as shown in Table 1.

<3点曲げ試験>
合金試料の常温での形状回復性(超弾性)を評価するため、3点曲げ試験を常温で行った。まず、合金試料から、長さ30mm×幅5mm×厚さ0.3mmの試験片を切り出した。試験機(株式会社島津製作所製、AG−I)内に設置された2つの支点(支点間距離20mm)上に試験片を載置した。試験片の中央(すなわち支点間の中心)に圧子を当てて負荷速度0.6mm/分で下向きに変位を与え、途中で上向きに方向を変更した。この間、応力−歪み曲線を連続的に記録して、図2に示される応力−歪み曲線を得た。得られた結果を、以下の基準で格付け評価したところ、表1に記されるとおり評価Aと判定された。
‐評価A:優れた形状回復を示し、残留歪みが1.0%未満であるもの
‐評価B:形状回復が劣り、残留歪みが1.0%以上であるもの
‐評価C:試験途中に試料が破断したもの
<3-point bending test>
In order to evaluate the shape recovery (superelasticity) of the alloy sample at room temperature, a three-point bending test was performed at room temperature. First, a test piece having a length of 30 mm, a width of 5 mm, and a thickness of 0.3 mm was cut out from the alloy sample. The test piece was placed on two fulcrums (distance between fulcrums 20 mm) installed in the testing machine (manufactured by Shimadzu Corporation, AG-I). An indenter was applied to the center of the test piece (that is, the center between the fulcrums) to give a downward displacement at a load speed of 0.6 mm / min, and the direction was changed upward in the middle. During this time, the stress-strain curve was continuously recorded to obtain the stress-strain curve shown in FIG. When the obtained results were rated and evaluated according to the following criteria, it was judged to be evaluation A as shown in Table 1.
-Evaluation A: Excellent shape recovery and residual strain less than 1.0%-Evaluation B: Poor shape recovery and residual strain of 1.0% or more-Evaluation C: Sample during test Is broken

例2(比較)
均質化処理後、水冷の代わりに、シリコンオイルでの油冷を行ったこと以外、例1と同様にして試料の作製及び評価を行った。油冷の冷却速度は2℃/秒と推定された。結果は表1、図3及び10に示されるとおりであった。
Example 2 (comparison)
After the homogenization treatment, samples were prepared and evaluated in the same manner as in Example 1 except that oil cooling was performed with silicon oil instead of water cooling. The cooling rate of oil cooling was estimated to be 2 ° C / sec. The results were as shown in Table 1, FIGS. 3 and 10.

例3(比較)
目標組成をCu−9.8Sn−4.5Siとしたこと以外、例1(水冷)と同様にして試料の作製及び評価を行った。結果は表1、図4及び9に示されるとおりであった。
Example 3 (comparison)
Samples were prepared and evaluated in the same manner as in Example 1 (water cooling) except that the target composition was Cu-9.8Sn-4.5Si. The results were as shown in Table 1, FIGS. 4 and 9.

例4(比較)
目標組成をCu−9.8Sn−4.5Siとしたこと以外、例2(油冷)と同様にして試料の作製及び評価を行った。結果は表1及び図5に示されるとおりであった。
Example 4 (comparison)
Samples were prepared and evaluated in the same manner as in Example 2 (oil cooling) except that the target composition was Cu-9.8Sn-4.5Si. The results were as shown in Table 1 and FIG.

例5(比較)
目標組成をCu−8.8Sn−5.7Siとしたこと以外、例1(水冷)と同様にして試料の作製及び評価を行った。結果は表1、図6及び9に示されるとおりであった。
Example 5 (comparison)
Samples were prepared and evaluated in the same manner as in Example 1 (water cooling) except that the target composition was Cu-8.8Sn-5.7Si. The results were as shown in Table 1, FIGS. 6 and 9.

例6(比較)
目標組成をCu−8.8Sn−5.7Siとしたこと以外、例2(油冷)と同様にして試料の作製及び評価を行った。結果は表1及び図7に示されるとおりであった。
Example 6 (comparison)
Samples were prepared and evaluated in the same manner as in Example 2 (oil cooling) except that the target composition was Cu-8.8Sn-5.7Si. The results were as shown in Table 1 and FIG.

例7(比較)
目標組成をCu−14.3Snとしたこと以外、例1(水冷)と同様にして試料の作製及び評価を行った。結果は表1及び図8に示されるとおりであった。
Example 7 (comparison)
Samples were prepared and evaluated in the same manner as in Example 1 (water cooling) except that the target composition was Cu-14.3 Sn. The results were as shown in Table 1 and FIG.

表1に示される結果から分かるように、Cu−12.6Sn−2.1Siの水冷品である例1の合金試料はβ相単相からなり、常温における優れた形状回復性(超弾性効果)を示した。一方、例3〜6のように例1の組成よりSi含有量が増えると、XRDプロファイルに不純物として示されるように、α相、δ相、ε相等の異相が析出し、β相単相でなくなり、結果的に優れた形状回復性(超弾性効果)を示さなかった。また、例1と同じ組成であっても、例2のように均質化処理後の冷却速度が油冷のように遅いと、β相主相の合金にα相、δ相、ε相等の異相が析出してβ相単相でなくなり、合金は脆く、優れた形状回復性(超弾性)を示さなかった。そのため、均質化処理後の冷却において、水冷(望ましくは氷水での水冷)程度の速い冷却速度が好ましいといえる。 As can be seen from the results shown in Table 1, the alloy sample of Example 1 which is a water-cooled product of Cu-12.6 Sn-2.1Si is composed of β-phase single-phase and has excellent shape recovery at room temperature (superelastic effect). showed that. On the other hand, when the Si content is higher than the composition of Example 1 as in Examples 3 to 6, different phases such as α phase, δ phase, and ε phase are precipitated as shown as impurities in the XRD profile, and the β phase is single phase. As a result, it did not show excellent shape recovery (superelastic effect). Further, even if the composition is the same as in Example 1, if the cooling rate after the homogenization treatment is slow as in oil cooling as in Example 2, different phases such as α phase, δ phase, and ε phase are added to the β phase main phase alloy. Precipitated and became non-β phase single phase, the alloy was brittle and did not show excellent shape recovery (superelasticity). Therefore, in the cooling after the homogenization treatment, it can be said that a cooling rate as fast as water cooling (preferably water cooling with ice water) is preferable.

また、図2に示される例1の合金試料(Cu−12.6Sn−2.1Siの水冷品)の応力−歪み曲線における応力最大値(約800MPa)は、図8に示される例7の合金試料(Cu−14.3Sn合金の水冷品)の応力−歪み曲線における応力最大値(約300MPa)よりもかなり高いことから、Cu−12.6Sn−2.1Siの水冷品である例1の合金試料は、従来のCu−Sn系合金よりも、格段に強度が高いことが分かる。また、図2及び図8の比較から、例1の合金試料は、例7の合金試料よりも形状回復性(超弾性)に優れることも分かる。 Further, the maximum stress value (about 800 MPa) in the stress-strain curve of the alloy sample of Example 1 shown in FIG. 2 (water-cooled product of Cu-12.6 Sn-2.1Si) is the alloy of Example 7 shown in FIG. Since it is considerably higher than the maximum stress value (about 300 MPa) in the stress-strain curve of the sample (water-cooled product of Cu-14.3 Sn alloy), the alloy of Example 1 which is a water-cooled product of Cu-12.6 Sn-2.1Si. It can be seen that the sample has much higher strength than the conventional Cu—Sn-based alloy. Further, from the comparison of FIGS. 2 and 8, it can be seen that the alloy sample of Example 1 is superior in shape recovery (superelasticity) to the alloy sample of Example 7.

Claims (5)

Sn:12.1〜13.1at%及びSi:1.6〜2.6at%を含有し、残部がCu及び不可避不純物である、β相単相からなる、Cu−Sn−Si系超弾性合金。 Sn: 12.1-13.1 at% and Si: 1.6-2.6 at%, the balance is Cu and unavoidable impurities, consisting of β-phase single phase, Cu-Sn-Si superelastic Elastic alloy. Sn含有量が12.6at%であり、かつ、Si含有量が2.1at%である、請求項に記載のCu−Sn−Si系超弾性合金。 The Cu—Sn—Si-based superelastic alloy according to claim 1 , wherein the Sn content is 12.6 at% and the Si content is 2.1 at%. 請求項1又は2に記載のCu−Sn−Si系超弾性合金の製造方法であって、
Sn:12.1〜13.1at%及びSi:1.6〜2.6at%を含有し、残部がCu及び不可避不純物である原料を溶解鋳造して、鋳造材を得る工程と、
前記鋳造材を均質化処理してβ相単相を形成させる工程と、
を含前記均質化処理が、前記鋳造材を650〜750℃の温度に保持した後、該鋳造材を水冷により急冷することを含む、Cu−Sn−Si系超弾性合金の製造方法。
The method for producing a Cu—Sn—Si-based superelastic alloy according to claim 1 or 2 .
A process of obtaining a cast material by melting and casting a raw material containing Sn: 12.1-13.1 at% and Si: 1.6 to 2.6 at%, the balance of which is Cu and unavoidable impurities.
A step of homogenizing the cast material to form a β-phase single-phase,
Only including, the homogenization treatment is, after holding the cast material to a temperature of 650 to 750 ° C., which comprises rapidly cooling by water cooling the the casting material, manufacturing method of the Cu-Sn-Si-based super-elastic alloy.
前記溶解鋳造が、800〜1300℃の温度で前記原料を溶解させた後、該原料を800℃から400℃までの間を50〜500℃/秒の冷却速度で冷却することを含む、請求項に記載の方法。 The claim comprises that the melting casting melts the raw material at a temperature of 800 to 1300 ° C. and then cools the raw material between 800 ° C. and 400 ° C. at a cooling rate of 50 to 500 ° C./sec. The method according to 3 . 前記急冷が氷水を用いて行われる、請求項3又は4に記載の方法。 The method according to claim 3 or 4 , wherein the quenching is performed using ice water.
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