Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C16/00—Alloys based on zirconium
• • 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S376/00—Induced nuclear reactions: processes, systems, and elements
  • Y10S376/90—Particular material or material shapes for fission reactors

Definitions

• a zirconium-base alloy resistant to corrosion contains 0.5 to 6% by weight of copper and at least one additive of magnesium, platinum or manganese in amounts from 0.1 to 5%, the balance being zirconium of nuclear purity.
• This invention relates to zirconium alloys and more specifically at leastv to the ternary alloys which have a high zirconium content.
• One important application of alloys of this type lies in the development of structural materials for use in nuclear reactors of the type which are cooled by circulation of carbon dioxide gas under pressure.
• zirconium-base alloys containing copper for the fabrication of construction materials employed in pressurized carbon-dioxide gas cooled reactors has already been contemplated.
• This invention is directed to the production of at least a ternary alloy having a zirconium base and containing copper which meets practical requirements more effectively than the alloys which were hitherto employed in the prior art, especially insofar as it has higher mechanical strength and improved creep strength at high temperature.
• the invention proposes a zirconium-base alloy which contains between 0.5 and 6% by weight of copper, characterized in that it comprises a total of 0.1 to 5% of at least one of the additives of the group constituted by magnesium, cerium, platinum and manganese (the proportion of cerium being at least 1% if it constitutes the sole additive), the remainder being nuclear pure zirconium.
• a noteworthy result thereby achieved is that, at a temperature of 500 to 600 C. and at a pressure varying between 25 and 60 bars, the strength of the alloy which is thus obtained is considerably greater than that of zirconium in the carbon dioxide gas which is commonly employed as coolant in nuclear reactors.
• the different impurities contained in the alloy, and in particular aluminum, titanium and silicon, must be present in as low a proportion as possible in order not to reduce the corrosion resistance of the alloy.
• the maximum proportions of aluminum, titanium and silicon which are present in the starting zirconium must be 0.01% by Weight in each case.
• zirconium which is employed for the fabrication of the alloy must be dehafniated; by .dehafniated zirconium is meant zirconium which contains a sufficiently low proportion of hafnium to prevent any appreciable increase in the neutron capture cross-section of the zirconium alloy. This is explained by the fact that hafnium has a high thermal-neutron cross-section and would thus have an unfavorable influence on the neutron characteristics of structural materials. Practically speaking, zirconium can be considered as hafnium-free or dehafniated when its hafnium content does not exceed 0.02% by weight.
• the best solution consists in utilizing as starting product in the fabrication of the alloy the so-called nuclear pure zirconium (reactor grade zirconium) which contains the following maximum percentages by weight of impurities.
• alloy compositions which are defined hereinabove have properties which permit of their use as structural materials (fuel element cans, especially ceramic materials such as U0 guide tubing and the like) in nuclear reactors which are cooled by circulation of carbon dioxide gas under pressure.
• the preparation of the alloy can be carried out by means of a number of different processes. It is possible in particular to employ nuclear pure zirconium sponge as starting material, to comminute the metal until granular particles are obtained and to distribute the copper and the other additive or additives in suitable proportions in the mass of granular material (the proportion of additive which is thus incorporated may be dependent on the quantities introduced by the zirconium).
• the mixture of granular material, copper and the other additive or additives is then compacted to form rods 30 mm. in diameter which are then melted in an electric furnace with a consumable electrode in a vacuum of the order of 10- mm. of mercury.
• the alloy ingots resulting from the initial melt are then re-melted in the electric furnace which is equipped with a consumable electrode and produce homogeneous ingots mm. in diameter which are readily adaptable to subsequent conversion processes.
• the corrosion resistance of the alloys defined above has been determined by their weight gain as compared with that of high-purity zirconium when the two metals are placed in a same carbon dioxide gas atmosphere for a predetermined length of time, at a predetermined temperature and pressure:
• EXAMPLE 1 A specimen of high-purity zirconium and a specimen of alloy containing 2.5% by weight of copper and 0.5% by weight of magnesium were placed in a carbon dioxide gas atmosphere containing 20 volumes per million of water vapor. At 600 C. and at a pressure of 60 bars, the weight gains reached after 800 hours were 4.20 mg./cm. of surface area in the case of unalloyed zirconium and 3.71 mg./cm. in the case of the alloy hereinabove defined; after 2,500 hours, the weight gains were 10.9 mg./
• a zirconium-base alloy consisting essentially of 0.5 to 6% by weight of copper, 0.1 to 5% of at least one of the additives of the group consisting of magnesium, platinum and manganese, the balance being zirconium of nuclear purity.
• a zirconium-base alloy consisting essentially of 1.5 to 2.5 by weight of copper and 0.5 to 1% of magnesium, the balance being zirconium.
• a zirconium-base alloy consisting essentially of 1.5 to 2.5 by weight of copper and approximately 0.2% of platinum, the balance being zirconium.
• An alloy in accordance with claim 1 consisting essentially of 1.5 to 2.5 by weight of copper and 0.3 to 1% of manganese, the balance being zirconium.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Catalysts (AREA)
• Conductive Materials (AREA)

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Citations (2)

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• 1965
  • 1965-08-27 FR FR29688A patent/FR1454541A/fr not_active Expired
• 1966
  • 1966-07-27 CH CH1088566A patent/CH460357A/fr unknown
  • 1966-08-03 DE DE19661533210 patent/DE1533210B1/de active Pending
  • 1966-08-04 BE BE685087D patent/BE685087A/xx unknown
  • 1966-08-10 GB GB35825/66A patent/GB1083057A/en not_active Expired
  • 1966-08-17 US US572885A patent/US3480430A/en not_active Expired - Lifetime
  • 1966-08-25 LU LU51823A patent/LU51823A1/xx unknown
  • 1966-08-25 NL NL6611974A patent/NL6611974A/xx unknown
  • 1966-08-26 ES ES0330602A patent/ES330602A1/es not_active Expired

Patent Citations (2)

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