JP3389018B2 - Zirconium alloy with excellent hydrogen absorption resistance - Google Patents
Zirconium alloy with excellent hydrogen absorption resistanceInfo
- Publication number
- JP3389018B2 JP3389018B2 JP20444096A JP20444096A JP3389018B2 JP 3389018 B2 JP3389018 B2 JP 3389018B2 JP 20444096 A JP20444096 A JP 20444096A JP 20444096 A JP20444096 A JP 20444096A JP 3389018 B2 JP3389018 B2 JP 3389018B2
- Authority
- JP
- Japan
- Prior art keywords
- hydrogen
- alloy
- hydrogen absorption
- zirconium alloy
- particles
- 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.)
- Expired - Fee Related
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Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Landscapes
- Manufacture And Refinement Of Metals (AREA)
- Powder Metallurgy (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、主として水冷却型
発電用原子炉の燃料部材に使用される、高温水または高
温水蒸気環境において耐食性にすぐれ、とくに対水素吸
収性にすぐれたジルコニウム合金に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zirconium alloy which is mainly used for a fuel member of a water-cooled power generation reactor and which has excellent corrosion resistance in high-temperature water or high-temperature steam environment, and particularly excellent hydrogen absorption.
【０００２】[0002]
【従来の技術】水冷却型発電用原子炉に使用されるジル
コニウム合金には、主として沸騰水型原子炉（ＢＷＲ）
に適用されるジルカロイ２（商品名、ただしJIS-H-475
1：ZrTN-802-D相当合金）や、主として加圧水型原子炉
（ＰＷＲ）に適用されるジルカロイ４（商品名、ただし
JIS-H-4751：ZrTN-804-D相当合金）などがある。これら
の合金は、炉心部の、燃料被覆管、チャンネルボック
ス、ウォーターチューブ、またはスペーサーなどの部品
として長期にわたる使用実績があり、現状の原子炉の環
境条件下で問題なく使用されている。2. Description of the Related Art Zirconium alloys used in water-cooled power reactors are mainly boiling water reactors (BWR).
Zircaloy 2 (trade name, provided with JIS-H-475
1: ZrTN-802-D equivalent alloy) and Zircaloy 4 (trade name, but mainly applied to pressurized water reactor (PWR))
JIS-H-4751: ZrTN-804-D equivalent alloy). These alloys have been used for a long time as parts such as a fuel cladding tube, a channel box, a water tube, or a spacer in the core part, and they are used without problems under the current environmental conditions of a nuclear reactor.
【０００３】しかし、最近原子炉の発電効率を高めるた
め、単位燃料あたりの発電量を増すいわゆる高燃焼度化
が進められている。この場合、装荷した燃料体の炉心に
滞在する時間が長くなるため、とくに燃料被覆管の腐食
量の増大と水素吸収量の増加が、その耐用期間を支配す
る要因として問題になる。水素吸収量が増してくると、
ジルコニウム合金中で水素化物が生成し、これが増加し
成長して合金が脆くなり、破損の危険性が増してくる。However, recently, in order to increase the power generation efficiency of a nuclear reactor, so-called high burnup has been promoted to increase the power generation amount per unit fuel. In this case, since the loaded fuel body stays in the core for a long time, an increase in the corrosion amount of the fuel cladding tube and an increase in the hydrogen absorption amount become problems as factors controlling the service life. As the amount of absorbed hydrogen increases,
Hydride forms in the zirconium alloy, which increases and grows, making the alloy brittle and increasing the risk of breakage.
【０００４】一般的にはジルコニウムの水による腐食、
すなわち下式
Ｚｒ＋２Ｈ2 Ｏ→ＺｒＯ2 ＋２Ｈ2 ・・・・・・(1)
のジルコニウムの酸化にともない、発生する水素が合金
中に吸収されることから、水素吸収の対策としては、耐
食性を向上させれば水素発生量が減じ水素吸収量を低減
できることになる。一方、ジルコニウム合金の水素吸収
は、Ｎｉの存在により増加することが知られており、こ
のために、加圧した水を冷却に使うＰＷＲ用のジルコニ
ウム合金のジルカロイ４は、特にＮｉ含有量を低く規制
している。Generally, zirconium is corroded by water,
That is, since hydrogen generated by the following formula Zr + 2H 2 O → ZrO 2 + 2H 2 ··· (1) is oxidized in the alloy, the corrosion resistance is improved as a countermeasure for hydrogen absorption. If this is done, the amount of hydrogen generated will be reduced and the amount of hydrogen absorbed can be reduced. On the other hand, it is known that the hydrogen absorption of a zirconium alloy is increased by the presence of Ni. Therefore, Zircaloy 4 of a zirconium alloy for PWR which uses pressurized water for cooling has a particularly low Ni content. Regulated.
【０００５】ジルコニウム合金の水素吸収を抑制する効
果のある添加元素として、Ｎｂがある。Ｎｂは、ジルコ
ニウムの耐食性を向上させる添加元素としてよく知られ
ていて、旧ソ連で実用化されたオゼナイト合金など以前
からいくつかのＮｂ含有合金が提案されてきた。たとえ
ば、特開昭60-36640号公報には、ジルカロイ２やジルカ
ロイ４をベースとし、これにＮｂを0.05〜 1.0％含有さ
せた合金の発明が開示されている。この場合、その耐食
性の向上によって、水素の吸収量が低下したものと思わ
れる。さらにこの合金を改良し、よりすぐれた水素吸収
特性を得たとして、ＣｒやＮｉの含有量はジルカロイ２
やジルカロイ４と同等であるが、Ｓｎの含有量を低く、
Ｆｅ含有量を高くして同様にＮｂを添加した合金の発明
も、特開昭63-33535号公報に提示されている。Nb is an additional element having an effect of suppressing hydrogen absorption of a zirconium alloy. Nb is well known as an additive element that improves the corrosion resistance of zirconium, and several Nb-containing alloys such as the ozenite alloy that has been put into practical use in the former Soviet Union have been proposed. For example, JP-A-60-36640 discloses an invention of an alloy based on Zircaloy 2 or Zircaloy 4 and containing 0.05 to 1.0% of Nb. In this case, it is considered that the absorption amount of hydrogen was reduced due to the improvement of the corrosion resistance. Assuming that this alloy is further improved and has better hydrogen absorption characteristics, the content of Cr and Ni is Zircaloy 2
Or Zircaloy 4, but with a low Sn content,
An invention of an alloy having a high Fe content and similarly added with Nb is also disclosed in JP-A-63-33535.
【０００６】原子炉内にて冷却水の経路に生じるＦｅお
よびＮｉの酸化物を主体とする水垢は、水流を阻害した
り、伝熱効率を低下させたり、さらには放射化して放射
線源を分散させたりする。最近、この水垢の生成抑制に
水への水素の添加が効果的であることが知られるように
なり、ＢＷＲなどでも冷却水に対する添加が検討されて
いる。水中溶存の水素量が増加すると、これに接してい
るジルコニウム合金は、腐食による水素だけでなく水中
の水素からの吸収量も増加する傾向にある。[0006] The scales mainly composed of oxides of Fe and Ni generated in the passage of cooling water in the nuclear reactor hinder the water flow, reduce the heat transfer efficiency, and further activate the radiation to disperse the radiation source. Or Recently, it has become known that the addition of hydrogen to water is effective in suppressing the formation of this scale, and the addition of hydrogen to cooling water is being studied in BWRs and the like. When the amount of hydrogen dissolved in water increases, the zirconium alloy in contact with the hydrogen tends to increase not only hydrogen due to corrosion but also absorption from hydrogen in water.
【０００７】腐食は合金表面から進行するので、これに
対する耐用期間の延長には管の肉厚を増すような対策も
考えられるが、水素吸収による脆化は、合金の内部で生
ずるものであり、厚みの増加は逆効果になることもあ
る。したがって、耐食性を向上させるばかりでなく、腐
食によって生じた水素や冷却水中の水素が、合金中に吸
収され難くする対策が必要である。また、最近燃料の燃
焼度を増加させる傾向にあるが、それにより使用期間が
増してくると、合金の水素吸収を抑止する対策はますま
す重要な課題になってくる。Since corrosion progresses from the surface of the alloy, it is conceivable to increase the wall thickness of the pipe in order to extend the service life against this, but embrittlement due to hydrogen absorption occurs inside the alloy. Increasing thickness can have the opposite effect. Therefore, it is necessary to take measures not only to improve the corrosion resistance, but also to make it difficult for hydrogen generated by corrosion and hydrogen in cooling water to be absorbed in the alloy. Moreover, although there is a tendency to increase the burnup of fuel recently, as a result of the increase in the usage period, measures to suppress hydrogen absorption of the alloy become an increasingly important issue.
【０００８】[0008]
【発明が解決しようとする課題】本発明の目的は、燃料
体の燃料被覆管や構造用部品に用いられる、耐水素吸収
性を向上させたジルコニウム合金の提供である。発電用
原子炉の高燃焼度化にともなう燃料体の炉内滞留期間の
増加や、冷却水中への水素添加のため、ジルコニウム合
金はその耐食性ばかりでなく耐水素吸収性も十分向上さ
せる必要がある。ことに水素吸収はその量が増すとジル
コニウムの水素化物が生成し、その増大が合金を脆化さ
せ破損事故に結びつくので十分な対処を要する。SUMMARY OF THE INVENTION An object of the present invention is to provide a zirconium alloy having improved hydrogen absorption resistance, which is used for a fuel cladding tube of a fuel body or a structural part. Zirconium alloy must have not only its corrosion resistance but also sufficient hydrogen absorption resistance due to the increase in the residence time of fuel in the reactor due to the higher burnup of power generation reactors and the addition of hydrogen to the cooling water. . In particular, when the amount of hydrogen absorption increases, hydride of zirconium is generated, and the increase thereof causes brittleness of the alloy and leads to a damage accident, so that sufficient measures must be taken.
【０００９】[0009]
【課題を解決するための手段】本発明者らは、ジルカロ
イ２の耐食性向上を目的に添加されるＮｉが水素吸収を
促進することから、Ｎｉが含有されていても水素吸収を
抑止できる対策について種々検討をおこなった。まず、
水素吸収が促進される原因を調査の結果、Ｎｉが含有さ
れている場合には第二相としてＺｒ2 Ｎｉの金属間化合
物が析出し、これが水素吸収の触媒として働いたり、水
素の拡散の経路となって吸収を促進させると考えられ
た。Means for Solving the Problems The present inventors have proposed measures for suppressing hydrogen absorption even when Ni is contained, because Ni added for the purpose of improving the corrosion resistance of Zircaloy 2 promotes hydrogen absorption. Various studies were conducted. First,
As a result of investigating the reason why hydrogen absorption is promoted, when Ni is contained, an intermetallic compound of Zr 2 Ni is precipitated as a second phase, which acts as a hydrogen absorption catalyst or a hydrogen diffusion route. And was thought to promote absorption.
【００１０】そこで、このＺｒ2 Ｎｉの金属間化合物の
作用を抑制する手段を検討の結果、Ｎｂの添加が有効で
あることが明らかになった。Ｎｂの添加は、従来より耐
食性の向上や、水素吸収を抑制する効果があることは知
られている。ところが、適量含有させた上で、とくにＺ
ｒ2 Ｎｉの金属間化合物の中に存在するＮｂとＮｉの
比、すなわちＮｂ／Ｎｉの原子濃度比を特定の範囲に制
御してやれば、著しく水素吸収を抑制できることを見い
だしたのである。さらに、このＮｂを特定量含有するＺ
ｒ2 Ｎｉの金属間化合物は、粒径が微細である方がより
水素吸収が少ないこともわかった。Then, as a result of studying means for suppressing the action of the Zr 2 Ni intermetallic compound, it was revealed that the addition of Nb is effective. It is known that the addition of Nb has the effects of improving the corrosion resistance and suppressing the hydrogen absorption. However, after containing an appropriate amount, especially Z
They have found that if the ratio of Nb and Ni existing in the intermetallic compound of r 2 Ni, that is, the atomic concentration ratio of Nb / Ni is controlled within a specific range, hydrogen absorption can be significantly suppressed. Furthermore, Z containing a specific amount of this Nb
It was also found that the intermetallic compound of r 2 Ni had smaller hydrogen absorption when the particle size was finer.
【００１１】この第二相のＺｒ2 Ｎｉ金属間化合物中の
Ｎｂが、水素吸収量を低減し水素化合物の生成を抑制す
る効果がある理由は必ずしも明らかでないが、次のよう
な機構によると考えれば、その効果を説明できる。The reason why Nb in the Zr 2 Ni intermetallic compound of the second phase has the effect of reducing the amount of hydrogen absorption and suppressing the production of hydrogen compounds is not always clear, but it is considered to be due to the following mechanism. If so, explain the effect.
【００１２】ＮｉやＮｉ系の化合物には水素吸収の触媒
的作用がある。これは、Ｎｉは水素分子を原子状の水素
に変えたり吸収したりするためである。一方、ジルコニ
ウム合金の表面で腐食により生成する緻密な酸化被膜
は、元来水素の拡散の障壁となることが知られている。
ただしその障壁としての効果を示すのは、金属表面に密
接した高々 0.3μm 程度の厚さの部分である。高温高圧
水にさらされたジルコニウム合金表面では、前出の式
(1) に示したように、腐食の進行によりＺｒＯ2 ができ
ると同時に水素が発生する。Ni and Ni-based compounds have a catalytic action for hydrogen absorption. This is because Ni converts or absorbs hydrogen molecules into atomic hydrogen. On the other hand, it is known that a dense oxide film formed by corrosion on the surface of a zirconium alloy originally serves as a barrier for hydrogen diffusion.
However, it is the portion with a thickness of at most about 0.3 μm that is in close contact with the metal surface that exhibits its effect as a barrier. For zirconium alloy surfaces exposed to high temperature and high pressure water,
As shown in (1), hydrogen is generated at the same time as ZrO 2 is formed due to the progress of corrosion.
【００１３】ところが、Ｚｒ2 Ｎｉ金属間化合物の粒子
が表面に存在すると、その中のＺｒが選択的に酸化さ
れ、濃化したＮｉが金属状になってその粒子の存在して
いた部分に取り残される。そうなると水素の拡散の障壁
となるべき酸化被膜に局所的にＮｉが食い込んだ形とな
り、上述のようにＮｉは水素を吸収されやすい状態に変
える作用を有し、しかも水素の通過経路を構成するの
で、合金への水素吸収を助長する。However, when particles of the Zr 2 Ni intermetallic compound are present on the surface, Zr therein is selectively oxidized, and the concentrated Ni becomes metallic and remains in the portion where the particles existed. Be done. If this happens, Ni will locally dig into the oxide film that should act as a barrier to the diffusion of hydrogen, and as described above, Ni has the effect of converting hydrogen into a state in which it is easily absorbed, and also constitutes the passage path for hydrogen. , Promotes the absorption of hydrogen into the alloy.
【００１４】Ｚｒ2 Ｎｉ金属間化合物にＮｂが固溶して
いると、相対的にＮｉの存在が薄められ局所的に存在す
るＮｉの濃度を低下させることもあるが、Ｎｂの存在が
酸化被膜に残存したＮｉの効果を阻害し、水素の吸収を
抑止するとも考えられる。When Nb is solid-dissolved in the Zr 2 Ni intermetallic compound, the presence of Ni may be relatively diluted and the concentration of locally existing Ni may be lowered. However, the presence of Nb causes an oxide film to form. It is also considered that the effect of Ni remaining in the above is obstructed and the absorption of hydrogen is suppressed.
【００１５】また、表面を覆う緻密な酸化被膜の、とく
に水素拡散の障壁のとなる厚さは 0.3μm 程度なので、
もしＺｒ2 Ｎｉ金属間化合物の粒子の大きさがこれより
大きければ、障壁となるべき被膜を突き抜けて水素通過
の経路となるＮｉが存在することになる。これに対し粒
子の径が障壁の厚さより十分小さければ、局在したＮｉ
による水素の通過を抑止できる。さらにＮｂの少量添加
は、ジルコニウム合金の高温相であるβ相を安定化させ
る効果があるので、冷却過程で析出する金属間化合物の
粒子の径を小さくさせる作用もあると推定される。Since the thickness of the dense oxide film covering the surface, which is a barrier for hydrogen diffusion, is about 0.3 μm,
If the size of the particles of the Zr 2 Ni intermetallic compound is larger than this, there will be Ni that penetrates through the film to be the barrier and serves as a path for hydrogen passage. On the other hand, if the particle diameter is sufficiently smaller than the barrier thickness, localized Ni
It is possible to suppress the passage of hydrogen due to. Furthermore, addition of a small amount of Nb has the effect of stabilizing the β phase, which is the high temperature phase of the zirconium alloy, and is therefore presumed to also have the effect of reducing the diameter of the intermetallic compound particles precipitated during the cooling process.
【００１６】以上のような水素吸収に対する合金中の第
二相の金属間化合物の作用に関して新たに見いだした知
見に基づき、その効果の限界を明確にし、さらにＳｎ、
Ｃｒ、Ｆｅなど他の元素の影響等を検討して、次のよう
な耐水素吸収性のすぐれた合金の発明を完成させた。Based on the newly found findings on the action of the intermetallic compound of the second phase in the alloy on the hydrogen absorption as described above, the limit of the effect was clarified, and Sn,
After examining the influence of other elements such as Cr and Fe, the invention of the following alloy having excellent hydrogen absorption resistance was completed.
【００１７】(1)質量％にて、Ｎｉ：0.01〜0.2％、Ｎ
ｂ：0.1〜1.5％を含有し、かつ析出したＺｒ ２ Ｎｉ金属
間化合物相中に含有されるＮｂとＮｉとの原子濃度比：
Ｎｂ／Ｎｉが0.5〜2.0であること、および上記の析出し
たＺｒ ２ Ｎｉ金属間化合物相の粒子の平均粒径が0.20μ
ｍ以下であることを特徴とする耐水素吸収性のすぐれた
ジルコニウム合金。(1) In mass% , Ni: 0.01 to 0.2%, N
b: Zr 2 Ni metal containing 0.1 to 1.5% and precipitated
Atomic concentration ratio of Nb and Ni contained in the intermetallic compound phase :
Nb / Ni is 0.5 to 2.0 , and the above-mentioned precipitation
The average particle size of the particles of the Zr 2 Ni intermetallic compound phase is 0.20μ
A zirconium alloy having an excellent hydrogen absorption resistance , which is characterized by being m or less .
【００１８】(2)ＮｉおよびＮｂの外に、質量％にて、
Ｓｎ：0.5〜２％、Ｃｒ：0.03〜0.2％、およびＦｅ：0.
10〜0.3％のうちの１種以上を含有することを特徴とす
る(1)に述べた耐水素吸収性のすぐれたジルコニウム合
金。(2) In addition to Ni and Nb, in mass% ,
Sn: 0.5-2%, Cr: 0.03-0.2%, and Fe: 0.
A zirconium alloy having excellent hydrogen absorption resistance as described in (1) , which contains one or more of 10 to 0.3%.
【００１９】金属間化合物中のＮｂ／Ｎｉの原子濃度
比、および金属間化合物の粒径を目的とする状態に制御
するには、まずβ温度に加熱して十分溶体化させた後急
冷する。その後α相域の適当な温度に加熱し、所定時間
保持することによってＺｒ2 Ｎｉを析出させると共にＮ
ｂをそこへ溶け込ませる。この場合、十分な過飽和固溶
の状態にしかつ析出粒子を微細にするために、溶体化後
の冷却速度は大きくする必要がある。そして、粒子が大
きくなり過ぎないようにして速やかに析出させ、かつＮ
ｂの濃度を大きくするには、その保持温度および時間の
選定が重要である。また、溶体化後急冷処理した後の熱
間加工や冷間加工は、粒子を微細にかつ均一に分散析出
させ、かつその析出を促進させる効果がある。In order to control the atomic concentration ratio of Nb / Ni in the intermetallic compound and the particle size of the intermetallic compound to a desired state, first, the solution is heated to β temperature, sufficiently solutionized, and then rapidly cooled. After that, by heating to an appropriate temperature in the α phase region and holding for a predetermined time, Zr 2 Ni is precipitated and N
Let b melt in there. In this case, it is necessary to increase the cooling rate after solution treatment in order to obtain a sufficiently supersaturated solid solution state and to finely precipitate particles. Then, the particles are promptly deposited so as not to become too large, and N
In order to increase the concentration of b, it is important to select the holding temperature and time. Further, the hot working or cold working after the solution treatment and the rapid cooling treatment has the effect of finely and uniformly dispersing and precipitating the particles and promoting the precipitation.
【００２０】なお、本発明における析出した第二相の粒
子に含有されるＮｂとＮｉとの原子濃度比は、分析装置
付きの透過型電子顕微鏡で測定することができる。ま
た、その平均粒径は、0.02μm 以上の粒子を対象とし、
電子顕微鏡観察によりその数および径を計測して求める
ものとする。The atomic concentration ratio of Nb and Ni contained in the precipitated second phase particles in the present invention can be measured by a transmission electron microscope equipped with an analyzer. Also, the average particle size is for particles of 0.02 μm or more,
It shall be determined by observing the number and diameter by electron microscope observation.
【００２１】[0021]
【発明の実施の形態】本発明のジルコニウム合金の組成
を限定した理由を以下に説明する。なお組成の「％」
は、とくに断らない限り「質量％」である。The reasons for limiting the composition of the zirconium alloy of the present invention will be described below. “%” Of the composition
Is “ mass% ” unless otherwise specified.
【００２２】Ｎｉは水素の吸収を助長する点からは、含
有していない方がよいが、耐食性向上効果があるので、
0.01〜 0.2％の範囲で含有させる。耐食性向上の効果を
得るために望ましい含有量は、0.01％以上であるが、
0.2％を超えるとＺｒ2 Ｎｉ金属間化合物が増加し、加
工性が劣化する。From the viewpoint of promoting the absorption of hydrogen, it is preferable that Ni is not contained, but since it has an effect of improving corrosion resistance,
It is contained in the range of 0.01 to 0.2%. The desirable content for obtaining the effect of improving the corrosion resistance is 0.01% or more,
If it exceeds 0.2%, the Zr 2 Ni intermetallic compound increases and the workability deteriorates.
【００２３】Ｎｂの含有量は 0.1％未満では、 0.2％以
下のＮｉを含有する場合、金属間化合物中のＮｂ／Ｎｉ
原子濃度比を本発明の 0.5〜2.0 の範囲に管理すること
が困難になる。また、Ｎｂ含有量が多くなりすぎるとβ
相が析出してきて、これが耐食性や加工性に悪影響を及
ぼすようになるので、含有量は多くても 1.5％までであ
る。したがってＮｂの含有量の範囲を 0.1〜 1.5％とす
る。When the content of Nb is less than 0.1%, and when Ni of 0.2% or less is contained, Nb / Ni in the intermetallic compound is contained.
It becomes difficult to control the atomic concentration ratio within the range of 0.5 to 2.0 of the present invention. Also, if the Nb content is too high, β
The phase precipitates, which adversely affects the corrosion resistance and workability, so the content is at most 1.5%. Therefore, the range of the Nb content is 0.1 to 1.5%.
【００２４】Ｓｎ、ＣｒおよびＦｅは、いずれも耐食性
および強度を向上させる効果があり、従来よりジルカロ
イ２やジルカロイ４などの合金に添加されている。本発
明合金には添加しなくてもよいが、添加すれば耐水素吸
収性を損なうことなく、合金の耐食性および強度を改善
することができる。ただし、これらの元素は、いずれも
少ない含有ではその改良効果は小さく、多すぎる含有は
逆に耐食性を劣化させたり加工性を悪くするので、それ
ぞれの含有量の限界を次のように定める。すなわち、Ｓ
ｎ： 0.5〜 2％、Ｃｒ：0.03〜 0.2％、およびＦｅ：0.
10〜0.3 ％である。特性を改善したい場合は、これらの
元素の１種以上を上記の量の範囲内で含有させればよ
い。Sn, Cr and Fe all have the effect of improving corrosion resistance and strength, and have been conventionally added to alloys such as Zircaloy 2 and Zircaloy 4. It is not necessary to add it to the alloy of the present invention, but if it is added, the corrosion resistance and strength of the alloy can be improved without impairing the hydrogen absorption resistance. However, if the content of each of these elements is small, the improvement effect is small, and if the content is too large, the corrosion resistance is deteriorated or the workability is deteriorated. Therefore, the respective content limits are set as follows. That is, S
n: 0.5-2%, Cr: 0.03-0.2%, and Fe: 0.
It is 10 to 0.3%. If it is desired to improve the characteristics, one or more of these elements may be contained within the above range.
【００２５】本発明合金は、通常原子炉級ジルコニウム
スポンジを原料として溶製し、上記添加元素以外は不可
避的不純物をふくむＺｒであることとするが、その他の
合金元素の添加はとくに排除するものではない。The alloy of the present invention is usually prepared by melting a reactor-grade zirconium sponge as a raw material and contains Zr containing inevitable impurities other than the above-mentioned additional elements, but the addition of other alloying elements is particularly excluded. is not.
【００２６】次に、析出した第二相中に含有されるＮｂ
とＮｉとの原子濃度比：Ｎｂ／Ｎｉを 0.5〜 2.0とする
理由は、 0.5未満の場合、耐水素吸収性の大きな改善が
認められず、 2.0を超える濃度比に上げても耐水素吸収
性のそれ以上の向上は得られないからである。その上、
2.0を超えるようにするには、前記のＮｂを溶け込ませ
る処理の際、温度を低めに選定した上で長時間の保持が
必要となってしまい、実用的でない。Next, Nb contained in the precipitated second phase
And Ni atomic concentration ratio: Nb / Ni is 0.5 to 2.0 because the hydrogen absorption resistance is not significantly improved when it is less than 0.5, and the hydrogen absorption resistance is increased even if the concentration ratio exceeds 2.0. This is because no further improvement can be obtained. Moreover,
If it exceeds 2.0, it is not practical because it is necessary to select a low temperature and hold for a long time in the process of dissolving Nb.
【００２７】析出した第二相の粒子の大きさは、粒子の
平均粒径が 0.2μm 以下であることとする。これは平均
粒径が 0.2μm を超える大きさになると、耐水素吸収性
の効果が低減してくるからである。望ましいのは 0.1μ
m 以下で、粒子の大きさは小さい方が好ましい。平均粒
径を求めるのは電子顕微鏡観察によるが、その場合、計
測する粒子の最小径を0.02μm とする。The size of the precipitated second phase particles is such that the average particle size of the particles is 0.2 μm or less. This is because the effect of hydrogen absorption resistance decreases when the average particle size exceeds 0.2 μm. 0.1μ is preferable
It is preferable that the particle size is smaller than m and the size of the particle is small. The average particle size is determined by electron microscope observation. In this case, the minimum particle size to be measured is 0.02 μm.
【００２８】このような析出第二相の、ＮｂとＮｉとの
原子濃度比および粒子の大きさの制御は次のようにす
る。まず、本発明で定める組成の鋳塊を溶製し、溶体化
処理すなわち溶体化後急冷する処理をおこなう。溶体化
温度の範囲はβ相の1000〜1200℃が望ましく、その後 1
50℃／ｓ以上の冷却速度でα相の低温域の 400℃〜常温
に急冷する。溶体化後急冷するのは、析出粒子が粗大化
する傾向のある冷却過程での析出を阻止するためであ
る。Control of the atomic concentration ratio of Nb and Ni and the size of the particles in the precipitated second phase is as follows. First, an ingot having the composition defined in the present invention is melted and subjected to a solution treatment, that is, a treatment of quenching after solution treatment. The solution temperature range is preferably 1000-1200 ℃ for β phase, and then 1
It is rapidly cooled at a cooling rate of 50 ° C / s or higher to 400 ° C in the low temperature range of α phase to room temperature. The reason for quenching after solution treatment is to prevent precipitation during the cooling process in which precipitated particles tend to become coarse.
【００２９】次に、押出し、鍛造、圧延などの熱間加
工、圧延、抽伸などの冷間加工、および焼鈍をおこなっ
て、最終製品とするが、この場合、熱間加工および焼鈍
の際の加熱温度を 450〜 700℃の範囲とし、その温度範
囲内における合計の保持時間を2〜50ｈとするのがよ
い。この合計の保持時間とは、熱間加工における加熱、
および焼鈍時の加熱の際の、合金が上記温度範囲内にあ
る期間の全累計時間である。これは、溶体化処理後、α
の所定温度域に保持することによって、微細な第二相の
析出と、その析出相へのＮｂの濃化を十分おこなわせる
ためである。Next, hot working such as extrusion, forging and rolling, cold working such as rolling and drawing, and annealing are performed to obtain a final product. In this case, heating during hot working and annealing is performed. It is preferable that the temperature is in the range of 450 to 700 ° C., and the total holding time within the temperature range is 2 to 50 hours. This total holding time means heating in hot working,
And the total cumulative time during which the alloy is in the above temperature range during heating during annealing. This means that after solution treatment, α
This is because by maintaining the temperature within the predetermined temperature range, the fine second phase is precipitated and the Nb is concentrated in the precipitated phase sufficiently.
【００３０】溶体化処理後の 700℃を超える温度への加
熱は析出物が粗大化しやすく、その上β相が出やすくな
るため、Ｎｂが所要原子濃度比にまで到達できなくな
る。また 450℃未満では、Ｎｂの濃化に時間がかかりす
ぎてしまう。望ましいのは加熱温度を 530〜 650℃の範
囲にすることで、この温度範囲にすれば析出粒子より効
果的に好ましい状態にすることができる。熱間加工や冷
間加工は、加熱時に析出粒子を細かく均一に分散させ、
かつその析出速度を大きくする効果がある。しかし、上
記の加熱温度範囲にある期間が 2ｈ未満では、Ｎｂが所
要原子濃度比にまで到達できない。また、50時間を超え
るようになると、析出粒子が粗大化してしまう。Heating to a temperature of more than 700 ° C. after the solution heat treatment tends to cause coarsening of precipitates and also makes it easier for β phase to occur, so that the required atomic concentration ratio of Nb cannot be reached. On the other hand, if the temperature is lower than 450 ° C, it takes too much time to concentrate Nb. Desirably, the heating temperature is set in the range of 530 to 650 ° C., and in this temperature range, a more preferable state can be obtained more effectively than the precipitated particles. In hot working and cold working, the precipitated particles are finely and uniformly dispersed during heating,
Moreover, it has the effect of increasing the deposition rate. However, if the period within the above heating temperature range is less than 2 hours, the required atomic concentration ratio of Nb cannot be reached. Further, if it exceeds 50 hours, the precipitated particles become coarse.
【００３１】[0031]
【実施例】表１に化学組成を示す合金をアーク溶解法に
て溶製し、熱間鍛造後、1000℃に加熱後水冷の溶体化処
理をおこなった。この場合変態点通過時の冷却速度は約
200℃／ｓであった。表面を切削して疵などを除去し、
厚さを整えた後、冷間圧延および中間焼鈍を 2回繰り返
した。 2回の中間焼鈍は 550℃、 600℃、または 640℃
にて 2ｈ均熱とし、それぞれの合金に対して 2回の焼鈍
の温度は同一にした。最終の冷間圧延後、 580℃、 2ｈ
の最終焼鈍をおこなった。 3回の冷間圧延は、いずれも
圧下率が約60％で、仕上板厚は 1.0mmとした。Example An alloy having a chemical composition shown in Table 1 was melted by an arc melting method, hot forged, heated to 1000 ° C., and water-cooled for solution treatment. In this case, the cooling rate when passing the transformation point is about
It was 200 ° C / s. Cutting the surface to remove flaws,
After adjusting the thickness, cold rolling and intermediate annealing were repeated twice. 550 ° C, 600 ° C, or 640 ° C for two intermediate anneals
Was soaked for 2 hours, and the temperature of the two annealings was made the same for each alloy. 580 ℃, 2h after final cold rolling
Was finally annealed. In all three cold rollings, the reduction rate was about 60% and the finished sheet thickness was 1.0 mm.
【００３２】[0032]
【表１】 [Table 1]
【００３３】得られた各合金の試作板片の、板厚の約 1
／4 の位置における第二相、すなわちＺｒ2 Ｎｉ系の金
属間化合物粒子が観察できるよう、機械研削、 5 vol％
ＨＦ−45 vol％ＨＮＯ3 の水溶液を用いた化学研磨、お
よび10 vol％Ｈ2 ＳＯ4 −メタノールの液を用いた電解
研磨をおこなって薄膜試料を作製した。分析装置付きの
透過電子顕微鏡により、この薄膜を観察し、析出してい
るＺｒ2 Ｎｉ系の金属間化合物について、そのＮｂ／Ｎ
ｉの原子濃度比、およびその粒径を測定した。測定した
粒子は大きさが0.02μm 以上のものとし、各試作板片に
対し、30個以上とした。About 1 of the plate thickness of the trial plate piece of each alloy obtained was obtained.
Mechanical grinding, 5 vol%, so that the second phase at the position of / 4, that is, Zr 2 Ni-based intermetallic compound particles can be observed.
A thin film sample was prepared by performing chemical polishing using an aqueous solution of HF-45 vol% HNO 3 and electrolytic polishing using a liquid of 10 vol% H 2 SO 4 -methanol. This thin film was observed with a transmission electron microscope equipped with an analyzer to determine the Nb / N ratio of the precipitated Zr 2 Ni-based intermetallic compound.
The atomic concentration ratio of i and its particle size were measured. The measured particles had a size of 0.02 μm or more, and 30 or more particles for each prototype plate piece.
【００３４】次に、各合金の試作板片により、耐水素吸
収性を評価した。幅20mm、長さ50mmの試片を切出して、
表面を#800エメリーペーパーにより湿式研磨し、脱脂乾
燥した。この試験片を水 1kgあたり40cc（ＮＴＰ：標準
状態）の水素を添加した 360℃、 200 kgf／cm2 の高温
加圧循環水中に 100日間浸漬した。Next, the hydrogen absorption resistance was evaluated using trial plate pieces of each alloy. Cut out a specimen with a width of 20 mm and a length of 50 mm,
The surface was wet-polished with # 800 emery paper and degreased and dried. This test piece was immersed for 100 days in high-temperature pressurized circulating water of 360 ° C. and 200 kgf / cm 2 to which 40 cc (NTP: standard state) of hydrogen was added per 1 kg of water.
【００３５】表１にこれらの試験結果を合わせて示す。
試験番号12は従来のジルコロイ２であるが、これに比較
して、第二相のＮｂ／Ｎｉの原子濃度比およびその平均
粒径が本発明の定める範囲に入る試験番号１〜７の合金
はいずれも水素吸収量が大幅に低減していることがわか
る。また、試験番号８〜11に見られるように、化学組成
としてＮｉ含有量が多い合金やＮｂ含有量が多すぎたり
少なすぎる合金は、本発明の定める第二相のＮｂ／Ｎｉ
の原子濃度比およびその平均粒径を逸脱する場合が多
く、水素吸収量の低減が得られていない。Table 1 also shows the results of these tests.
Test No. 12 is the conventional Zircoloy 2, but in comparison to this, the alloys of Test Nos. 1 to 7 in which the atomic concentration ratio of Nb / Ni of the second phase and its average particle size fall within the range defined by the present invention are It can be seen that the hydrogen absorption amount is significantly reduced in all cases. Further, as seen in Test Nos. 8 to 11 , an alloy having a high Ni content or an alloy having a too high or a low Nb content as a chemical composition is a second phase Nb / Ni defined by the present invention.
It often deviates from the atomic concentration ratio and the average particle size thereof, and reduction of the hydrogen absorption amount has not been obtained.
【００３６】[0036]
【発明の効果】本発明のジルコニウム合金は、耐水素吸
収性がすぐれているので、原子炉内にて使用中の合金内
部の水素化物生成を抑止し、合金の脆化進行を遅くする
ことができる。この合金を燃料体の燃料被覆管や構造用
部品に用いることにより、燃料体の炉内滞留期間を延長
でき、燃料の高燃焼化を容易にするので発電用原子炉の
効率向上が可能となる。Since the zirconium alloy of the present invention has excellent resistance to hydrogen absorption, it can suppress the formation of hydride inside the alloy in use in a nuclear reactor and slow the progress of embrittlement of the alloy. it can. By using this alloy for the fuel cladding tube and structural parts of the fuel body, it is possible to extend the residence time of the fuel body in the reactor and facilitate higher combustion of the fuel, thus improving the efficiency of the nuclear reactor for power generation. .
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭63−145735（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C22C 1/00 - 49/14 C22F 1/00 - 3/02 G21C 3/07 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-145735 (JP, A) (58) Fields investigated (Int.Cl. 7 , DB name) C22C 1/00-49/14 C22F 1 / 00-3/02 G21C 3/07
Claims (2)
0.1〜1.5％を含有し、かつ析出したＺｒ ２ Ｎｉ金属間化
合物相中に含有されるＮｂとＮｉとの原子濃度比：Ｎｂ
／Ｎｉが0.5〜2.0であること、および上記の析出したＺ
ｒ ２ Ｎｉ金属間化合物相の粒子の平均粒径が0.20μｍ以
下であることを特徴とする耐水素吸収性のすぐれたジル
コニウム合金。1. In mass% , Ni: 0.01 to 0.2%, Nb:
Precipitated Zr 2 Ni intermetallic containing 0.1-1.5%
Atomic concentration ratio of Nb and Ni contained in the compound phase : Nb
/ Ni is 0.5 to 2.0 , and the above-mentioned precipitated Z
The average particle size of the particles of the r 2 Ni intermetallic compound phase is 0.20 μm or less.
A zirconium alloy having excellent hydrogen absorption resistance , which is characterized by:
ｎ：0.5〜２％、Ｃｒ：0.03〜0.2％、およびＦｅ：0.10
〜0.3％のうちの１種以上を含有することを特徴とする
請求項１に記載の耐水素吸収性のすぐれたジルコニウム
合金。2. In addition to Ni and Nb, in mass% , S
n: 0.5-2%, Cr: 0.03-0.2%, and Fe: 0.10.
The zirconium alloy with excellent hydrogen absorption resistance according to claim 1, characterized in that it contains at least one of 0.3 to 0.3%.
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|---|---|---|---|
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