JP2018514650A - Zirconium alloy having excellent corrosion resistance and creep resistance, and method for producing the same - Google Patents

Abstract

The present invention relates to a zirconium alloy composed of niobium 1.1-1.2% by weight, phosphorus 0.01-0.2% by weight, iron 0.2-0.3% by weight and the balance zirconium, A first stage in which a mixture which is a component of a zirconium alloy is melted to produce an ingot, and the ingot produced in the first stage is solution-treated at 1000 to 1050 ° C. (β phase section) for 30 to 40 minutes. After the heat treatment, the second stage of β-quenching after quenching in water and preheating the ingot heat-treated in the second stage at 630-650 ° C. for 20-30 minutes, then 60-65% A third stage of hot rolling at a rolling reduction ratio of 30%, and after rolling the rolling material hot-rolled in the third stage at 570-590 ° C. for 3-4 hours, followed by a rolling reduction ratio of 30-40%. 1st cold rolling After the fourth stage and the secondary cold-rolled material first cold-rolled in the fourth stage at 560-580 ° C. for 2-3 hours, the secondary cold-rolling is performed at a reduction rate of 50-60%. The third intermediate vacuum heat treatment at 560 to 580 ° C. for 2 to 3 hours, and then the third cold at a rolling reduction of 30 to 40%. Including a sixth stage of rolling and a seventh stage of final vacuum heat treatment of the rolled material that has been third cold rolled in the sixth stage at 440 to 650 ° C. for 7 to 9 hours, thereby providing corrosion resistance and resistance to creep deformation. An object is to provide a method for producing a zirconium alloy having excellent performance. [Selection] Figure 1

Description

  The present invention relates to a zirconium alloy having excellent corrosion resistance and creep resistance, and a method for producing the same, and in particular, a zirconium alloy composition and heat treatment conditions used for nuclear fuel cladding tubes and support grids of light water reactors and heavy water reactor type nuclear power plants. About.

Zirconium alloy is an alloy with low neutron absorption cross section, excellent corrosion resistance and mechanical properties, and has been used for several decades as a material for fuel cladding tubes, fuel assembly support grids and reactor structures. It has been widely used in PWR (Pressurized Water Reactor) and Boiling Water Reactor (BWR).
Zircaloy-2 (Zircaloy-2, Sn 1.20 to 1.70% by weight, Fe 0.07 to 0.20% by weight, Cr 0.05 to 1.15% by weight, Ni 0.03 to 0.3% developed so far. 08 wt%, O900-1500 ppm, Zr balance) and Zircaloy-4 (Zircaloy-4, Sn 1.20-1.70 wt%, Fe 0.18-0.24 wt%, Cr 0.07-1.13 wt%, O900-1500 ppm, Ni <0.007 wt%, Zr balance) alloys are most widely used.

Recently, however, high burnup nuclear fuel has been considered as part of efforts to improve the economic efficiency of nuclear reactors. However, existing zircaloy-2 and zircaloy-4 have been used as materials for nuclear fuel cladding. When used, it causes many problems in mechanical properties such as corrosion and creep properties.
This has led to the emergence of the need to develop materials with excellent corrosion resistance and creep resistance that are most problematic under conditions of high burnup and long cycle. Recently, as part of such efforts, Zr-Nb series Research on the development of suitable zirconium alloys such as alloys is underway.
Considering the prior art, U.S. Pat. No. 4,649,023 discloses that zirconium, niobium 0.5 to 2.0% by weight, tin 0.9 to 1.5% by weight are essential elements, iron, chromium, molybdenum. , A zirconium alloy containing 0.09 to 0.11% by weight of any one element of vanadium, copper, nickel and tungsten and 0.1 to 0.16% by weight of oxygen is disclosed. Also disclosed is a method for producing an alloy product in which precipitates having a fine size of 80 nm or less are uniformly distributed in the matrix phase.

US Pat. No. 5,648,995 discloses a cladding tube using a zirconium alloy composed of 0.8 to 1.3% by weight of niobium, 50 to 250 ppm of iron, 1600 ppm or less of oxygen, and 120 ppm or less of silicon. .
The alloy is heat-treated at 600 to 800 ° C. and then extruded, cold rolling is performed 4 to 5 times, and intermediate heat treatment during cold rolling is 2 to 4 in the temperature range of 565 to 605 ° C. The fuel cladding tube was manufactured by performing the heat treatment for a time and performing the final heat treatment at 580 ° C.
At this time, in order to improve creep resistance, iron in the alloy composition is limited to 250 ppm or less, and oxygen is limited to a range of 1000 to 1600 ppm.
In US Pat. No. 6,325,966, niobium 0.15 to 0.25 wt%, tin 1.10 to 1.40 wt%, iron 0.35 to 0.45 wt%, chromium 0.15 to 0 Corrosion resistance comprising 25% by weight as an essential element, 0.08 to 0.12% by weight of any one element of molybdenum, copper and manganese, 1000 to 1400 ppm of oxygen, and the balance zirconium And an alloy with excellent mechanical properties was designed.

As can be seen from the prior art, in a conventional zirconium alloy containing Sn in Nb, the corrosion resistance and mechanical properties are improved by changing the kind and amount of additive elements or changing the heat treatment conditions. Research is ongoing to obtain a zirconium alloy composition for burnup.
At this time, the optimum conditions for the excellent corrosion resistance and mechanical properties of the zirconium alloy are affected by the type of additive element, the amount added, the processing conditions, and the heat treatment conditions. is necessary.
Therefore, the present inventors improved the creep resistance while greatly increasing the corrosion resistance by removing Sn from the Zr—Nb alloy system and adding P, Ta, etc. to adjust the composition and heat treatment temperature. The present invention has been completed.

US Registered Patent Publication No. 4649023 (Registration Date: March 10, 1987) US Registered Patent Publication No. 5648995 (Registration date: July 15, 1997) US Registered Patent Publication No. 6325966 (Registration Date: December 4, 2001)

  Accordingly, the present invention has been devised to solve the above-described problems, and its purpose is to remove tin that adversely affects corrosion resistance and maintain niobium, phosphorous in order to maintain creep resistance. It is an object of the present invention to provide a zirconium alloy composition and a final heat treatment condition in which corrosion resistance and creep resistance are improved in consideration of optimum heat treatment conditions by adding tantalum or the like.

In order to achieve the above object, the zirconium alloy according to the present invention basically includes niobium 1.1 to 1.2% by weight, phosphorus 0.01 to 0.2% by weight, iron 0.2 to 0.3%. It is characterized by comprising weight percent and the balance zirconium.
At this time, phosphorus is preferably 0.02 to 0.07% by weight.
Preferably, the zirconium alloy may further contain 0.01 to 0.15% by weight of tantalum (Ta) in order to improve corrosion resistance and resistance to creep deformation.
More preferably, tantalum (Ta) can be added in an amount of 0.03 to 0.1% by weight.

On the other hand, the method for producing a zirconium alloy according to the present invention comprises niobium 1.1 to 1.2% by weight, phosphorus 0.01 to 0.2% by weight, iron 0.2 to 0.3% by weight and the balance zirconium. A first stage of dissolving the composed mixture to produce an ingot;
A second stage in which the ingot produced in the first stage is subjected to solution heat treatment at 1000 to 1050 ° C. (β phase section) for 30 to 40 minutes, and then rapidly cooled in water and β-quenched (β-Quenching);
A third stage in which the ingot heat-treated in the second stage is pre-heated at 630 to 650 ° C. for 20 to 30 minutes and then hot-rolled at a rolling reduction of 60 to 65%;
A fourth stage in which the rolled material hot-rolled in the third stage is subjected to primary intermediate vacuum heat treatment at 570 to 590 ° C. for 3 to 4 hours, and then first cold-rolled at a reduction rate of 30 to 40%;
A fifth stage in which the first cold-rolled material in the fourth stage is subjected to a secondary intermediate vacuum heat treatment at 560 to 580 ° C. for 2 to 3 hours, followed by a second cold rolling at a reduction rate of 50 to 60%; ,
A sixth step of subjecting the rolled material secondarily cold-rolled in the fifth step to a third intermediate vacuum heat treatment at 560 to 580 ° C. for 2 to 3 hours, followed by a third cold rolling at a reduction rate of 30 to 40%; ,
And a seventh step of subjecting the rolled material that has been third cold rolled in the sixth step to a final vacuum heat treatment at 440 to 650 ° C. for 7 to 9 hours.

At this time, phosphorus in the first stage is preferably 0.02 to 0.07% by weight, and the temperature of the final vacuum heat treatment in the seventh stage is preferably 460 to 600 ° C. to optimize the corrosion resistance and the resistance to creep deformation. Can be
Preferably, the corrosion resistance can be further improved by adding 0.01 to 0.15% by weight of tantalum (Ta) to the mixture in the first stage.
Particularly preferably, the tantalum (Ta) is 0.03 to 0.1% by weight, and the temperature of the final vacuum heat treatment in the seventh stage is 460 to 530 ° C., so that the corrosion resistance and the resistance to creep deformation are maximized. Can be increased.
On the other hand, before dissolving the mixture in the first stage, it is preferable to compact phosphorus to prevent precipitation of phosphorus.

  The zirconium alloy according to the present invention not only has excellent corrosion resistance as compared with Zircaloy-4 by completely removing tin, but also by controlling the kind of additive element such as P and Ta, the amount added, and the final heat treatment condition. Since the creep resistance is also high, there is an effect that it can be very usefully used for a fuel cladding tube or the like in a reactor core of a light water reactor or a heavy water nuclear power plant.

It is a graph which shows the weight increase amount after the corrosion test of the zirconium alloy which concerns on this invention with a test day. It is a graph which shows the deformation after the creep test of the zirconium alloy which concerns on this invention.

  The specific structure or function described in the embodiments of the present invention is merely illustrated for the purpose of illustrating the embodiments according to the concept of the present invention. Can be implemented. In addition, the present invention should not be construed as limited to the embodiments described herein, but is understood to include all modifications, equivalents, or alternatives that fall within the spirit and scope of the present invention. Should be.

Hereinafter, the present invention will be described in detail.
The zirconium alloy according to the present invention is composed of niobium 1.1-1.2% by weight, phosphorus 0.02-0.05% by weight, iron 0.2-0.3% by weight and the balance zirconium.
The niobium is composed of 1.1 to 1.2% by weight, phosphorus 0.02% by weight, iron 0.2 to 0.3% by weight and the balance zirconium.
Further, it is composed of 1.1 to 1.2% by weight of niobium, 0.05% by weight of phosphorus, 0.2 to 0.3% by weight of iron and the remaining zirconium.
Further, by adding tantalum to the zirconium alloy, niobium 1.1 to 1.2% by weight, phosphorus 0.05% by weight, tantalum 0.03 to 0.04% by weight, iron 0.2 to 0.3% by weight And the balance zirconium.
Further, by adding tantalum to the zirconium alloy, niobium 1.1 to 1.2% by weight, phosphorus 0.05% by weight, tantalum 0.09 to 0.1% by weight, iron 0.2 to 0.3% by weight And the balance zirconium.

Hereinafter, the production of the zirconium alloy according to the present invention having the above-described configuration will be described.
The method for producing a zirconium alloy according to the present invention includes:
A first stage in which a mixture of zirconium alloy composition elements is melted to produce an ingot; the ingot produced in the first stage is solutionized at 1000 to 1050 ° C. (β phase section) for 30 to 40 minutes A second stage of β-quenching that is quenched in water after heat treatment; after preheating the ingot heat-treated in the second stage at 630 to 650 ° C. for 20 to 30 minutes, 60 to 65% A third stage of hot rolling at a reduction ratio; the rolled material hot-rolled in the third stage is subjected to a first intermediate vacuum heat treatment at 570 to 590 ° C. for 3 to 4 hours, and then 1 at a reduction ratio of 30 to 40%. In the fourth stage of the next cold rolling, and after the second intermediate vacuum heat treatment at 560 to 580 ° C. for 2 to 3 hours after the primary cold rolling in the fourth stage, the rolling reduction is 50 to 60%. 5th stage of secondary cold rolling A sixth step of subjecting the rolled material secondarily cold-rolled in the fifth step to a third intermediate vacuum heat treatment at 560 to 580 ° C. for 2 to 3 hours, followed by a third cold rolling at a reduction rate of 30 to 40%; And a seventh step of subjecting the rolled material that has been third cold rolled in the sixth step to a final vacuum heat treatment.

Hereinafter, various embodiments of the present invention having the above-described steps will be described in more detail as examples.
<Examples 1 to 12> Manufacture of zirconium alloy (1) Manufacture of ingot First, in the first stage, niobium 1.2 wt%, phosphorus 0.02 to 0.05 wt%, tantalum 0.03 to 0.1 % By weight, 0.2% by weight of iron and the remainder of the zirconium are produced in an ingot using a vacuum arc melting method (VAR, Vacuum Arc Remelting).
Zirconium used is a nuclear grade zirconium sponge specified in ASTM B349, and elements added with niobium, phosphorus, tantalum, iron, etc. are high purity elements of 99.99% or more. used.
At this time, in order to prevent segregation of impurities and uneven distribution of the alloy composition, it is repeated about 3 times, and after maintaining the vacuum in the chamber of the arc melting apparatus sufficiently at 10 ⁻⁵ torr or less, The alloy was melted to produce an ingot. At this time, phosphorus (P) was compacted and dissolved unlike other alloy elements in order to prevent precipitation.
In order to prevent oxidation on the surface of the test piece during the cooling process, an inert gas such as argon was injected and cooled.

(2) β solution heat treatment (β-Annealing) and β-quenching (β-Quenching)
In the second stage, β-solution heat treatment and β-quenching are performed, and after solution treatment at 1000 to 1050 ° C., which is a β-phase temperature range, for 30 minutes, water cooling is performed at a rate of about 300 ° C./sec or more. . At this time, in order to prevent oxidation of the ingot, spot welding was performed by coating with a stainless steel plate having a thickness of 1 mm (Stainless Steel Plate). This step is performed in order to homogenize the alloy composition in the manufactured ingot and to uniformly distribute the size of second phase precipitates (SPP) in the base metal.

(3) Heat treatment and hot rolling In the third stage, β-quenched test pieces are hot rolled.
At this time, after preheating at 630 to 650 ° C. for about 20 to 30 minutes, rolling was performed at a rolling reduction of about 60 to 65%. If it deviates from the above heat treatment temperature, it is difficult to obtain a rolled material suitable for the next fourth stage processing. Further, when the rolling reduction during hot rolling is less than 60%, there is a problem that the texture of the zirconium material is uneven and the hydrogen embrittlement resistance is lowered, and the rolling reduction during hot rolling. When the ratio is 80% or more, it is reported that there is a problem in later workability.
After the hot-rolled rolled material is removed from the coated stainless steel plate, an oxide film and a pickling solution having a volume ratio of water: nitric acid: hydrofluoric acid of 50:40:10 are used. The impurities were removed, and the remaining oxide film was completely removed using a wire brush for the subsequent process.

(4) Primary intermediate heat treatment and primary cold rolling About 3 to 4 at about 580 to 590 ° C. in order to remove residual stress after hot rolling and prevent breakage of the test piece during primary cold working. A primary vacuum heat treatment was performed while maintaining the degree of vacuum at 10 ⁻⁵ torr or less.
The intermediate vacuum heat treatment is preferably performed by raising the temperature to the recrystallization heat treatment temperature. If the intermediate vacuum heat treatment is out of the above temperature range, there is a possibility that a problem that the corrosion resistance is lowered may occur.
Primary cold rolling was performed on the rolled material that had been subjected to the primary intermediate vacuum heat treatment at a rolling reduction of about 40 to 50% at intervals of about 0.3 mm per pass.
(5) Secondary intermediate vacuum heat treatment and secondary cold rolling Secondary intermediate vacuum heat treatment was performed at 570 to 580 ° C. for about 2 to 3 hours on the primary cold rolled material.
If it deviates from the temperature of the intermediate heat treatment, there is a possibility that a problem of reducing corrosion resistance may occur.
Secondary cold rolling was performed on the rolled material subjected to the secondary intermediate vacuum heat treatment at a reduction rate of about 50 to 60% at intervals of about 0.3 mm per pass.

(6) Third intermediate vacuum heat treatment and third cold rolling A third intermediate vacuum heat treatment was performed on the rolled material subjected to the second cold rolling at 570 to 580 ° C. for 2 to 3 hours.
If it deviates from the temperature of the intermediate heat treatment, there is a possibility that a problem of reducing corrosion resistance may occur.
Third cold rolling was performed on the rolled material that had been subjected to the third intermediate vacuum heat treatment at a reduction rate of about 30 to 40% at intervals of about 0.3 mm per pass.
(7) Final vacuum heat treatment The final heat treatment of the rolled material subjected to the third cold rolling is performed in a high vacuum atmosphere of 10 ⁻⁵ torr or less.
The final heat treatment was performed at 460 to 580 ° C. for 8 hours.
The specific alloy composition and final heat treatment temperature of the zirconium alloy according to the present invention are summarized in Table 1.

<Comparative Examples 1-2>
In Comparative Examples 1 and 2, a cladding tube of Zircaloy-4, which is a commercial zirconium alloy used in nuclear power plants, was used.

<Experimental Example 1> Corrosion Resistance Experiment In order to investigate the corrosion resistance of the zirconium alloy composition according to the present invention, the following corrosion test was performed.
After the plate material test piece was manufactured in the above manufacturing process using the zirconium alloys of Examples 1 to 12, a test piece for a plate material corrosion test having a size of 20 mm × 20 mm × 1.0 mm was manufactured. Mechanical polishing was performed step by step using abrasive paper.
The surface-polished test piece is pickled using a solution of water: nitric acid: hydrofluoric acid = 50: 40: 10 (volume ratio), ultrasonically washed with acetone, and then sufficiently dried for 24 hours or more with a dryer. Dried.
In order to determine the degree of corrosion of the alloy, the surface area and initial weight of the alloy were measured prior to charging into the autoclave.
The loaded test piece was subjected to a corrosion test for 100 days using a static autoclave in a pure water atmosphere and a 70 ppm Li water atmosphere at 360 ° C. and 18.6 MPa.
When performing the corrosion test, not only Examples 1 to 12 but also commercial Zircaloy-4 of Comparative Example 1 was put together and tested.
After the corrosion test, the test pieces were taken out for a total of 8 times for 260 days and their respective weights were measured, and then the weight increase was calculated to quantitatively evaluate the degree of corrosion. The results are shown in the table below.

In the following, the results of the corrosion test are 1) the respective results when phosphorus is added at 0.02 wt% and 0.05 wt% without tantalum, and 2) the phosphorus component is 0.05 wt% In some cases, tantalum is added separately at 0.03% by weight and 0.1% by weight. In this case, in both the above 1) and 2), all the experiments were performed for the three cases where the final heat treatment temperatures were 460 ° C., 520 ° C., and 580 ° C., respectively.
Results when phosphorus is added at 0.02 wt% and 0.05 wt% without tantalum

From Table 2, it can be seen that the difference in corrosion resistance between the case of Comparative Example 1 where no phosphorus is added and the case where 0.02% of phosphorus is added and the final heat treatment temperature is 460 ° C. is significant. In particular, the cases of Examples 2, 6, and 10 in which the amount of phosphorus added is 0.05% are higher than those in Examples 1, 5, and 9 in which the amount of phosphorus added is 0.02% by weight. It can be seen that
Therefore, in relation to the component ratio of phosphorus, there is a significant difference in corrosion resistance when phosphorus is added even in a small amount, so that the amount of phosphorus added is 0.02% by weight in view of the phosphorus of Example 1 being 0.02% by weight. From the case of 0.01% by weight, it is predicted that there is a clear improvement in corrosion resistance.
However, when the corrosion resistance is remarkably improved, it can be considered that the experimental value is 0.02 wt% to 0.07 wt%. In Examples 2, 6 and 10, the phosphorus component was 0.05% by weight, but an increase in corrosion resistance was observed when 0.05% by weight of phosphorus compared to 0.02% by weight. Therefore, it is fully predicted that at least a significant improvement in corrosion resistance can be maintained even in the case of 0.07% by weight.

  2) Results when tantalum was added at 0.03% and 0.1% by weight with the phosphorus component at 0.05% by weight

Examples 2, 6 and 10 are cases where only phosphorus was added without tantalum, Examples 3, 7 and 11 were cases where 0.03% by weight of tantalum was added, and Examples 4, 8 and 12 were This is a case where 0.1% by weight of tantalum is added.
When tantalum is 0.1% by weight, there is a significant increase in corrosion resistance in Example 4 with a final heat treatment temperature of 460 ° C. and Example 8 with a final heat treatment temperature of 520 ° C., where tantalum is 0.03% by weight. It is observed that there is a slight increase in corrosion resistance, though only slightly.
Therefore, it is predicted from experimental results that tantalum has an increase in corrosion resistance when the component ratio is 0.01% by weight to 0.15% by weight, and a further significant increase in corrosion resistance is 0.03% by weight to 0.3%. Experiments prove that this is the case for 1% by weight.

<Experimental Example 2> Creep Experiment In order to investigate the creep resistance of the zirconium alloy composition according to the present invention, the following creep test was performed.
A plate test piece was manufactured in the above manufacturing process using the zirconium alloys of Examples 1 to 4, and then a creep test piece was manufactured.
Further, in order to compare the creep characteristics, the commercial cladding tube of Comparative Example 1 was copied, and a Zircaloy-4 test piece of Comparative Example 2 of the plate type was manufactured in the same process. At this time, the final heat treatment temperature of Comparative Example 2 was set to 460 ° C. which is the same condition as in Examples 1 to 4 and Comparative Example 1, and a creep test was performed.
The creep test was performed for 120 hours at 350 ° C. with a constant load of 120 MPa. The test results are shown in Table 4 in comparison with the results of Comparative Example 2.

As shown in Table 4, Examples 1 to 4 having the zirconium alloy composition according to the present invention were evaluated in a stress condition of 350 ° C. and 120 MPa for 10 days. As a result, the creep deformation amount was in the range of 0.22 to 0.34. And measured. In particular, the amount of creep deformation greatly decreased as the amount of Ta increased. On the other hand, the creep deformation amount of Comparative Example 2 is 0.46, which is much larger than those of Examples 1 to 4.
Therefore, it can be seen that the resistance characteristic against creep deformation is effective when phosphorus is added even in a small amount, and the resistance characteristic against creep deformation is remarkably enhanced as the amount of tantalum added is increased.
The present invention described above is not limited by the above-described embodiments and the accompanying drawings. Without departing from the technical idea of the present invention. It will be apparent to those skilled in the art to which the present invention pertains that various substitutions, modifications and changes can be made.

Claims (9)

  A zirconium alloy composition composed of 1.1 to 1.2% by weight of niobium, 0.01 to 0.2% by weight of phosphorus, 0.2 to 0.3% by weight of iron and the balance zirconium.   The zirconium alloy composition according to claim 1, wherein phosphorus is 0.02 to 0.07 wt%.   The zirconium alloy according to claim 1, wherein tantalum (Ta) is further added in an amount of 0.01 to 0.15% by weight.   Zirconium alloy according to claim 3, characterized in that tantalum (Ta) is 0.03 to 0.1% by weight. A mixture composed of 1.1 to 1.2% by weight of niobium, 0.01 to 0.2% by weight of phosphorus, 0.2 to 0.3% by weight of iron, and the balance zirconium is dissolved in an ingot. A first stage of manufacturing;
A second stage in which the ingot produced in the first stage is subjected to solution heat treatment at 1000 to 1050 ° C. (β phase section) for 30 to 40 minutes, and then rapidly cooled in water and β-quenched (β-Quenching);
A third stage in which the ingot heat-treated in the second stage is pre-heated at 630 to 650 ° C. for 20 to 30 minutes and then hot-rolled at a rolling reduction of 60 to 65%;
A fourth stage in which the rolled material hot-rolled in the third stage is subjected to primary intermediate vacuum heat treatment at 570 to 590 ° C. for 3 to 4 hours, and then first cold-rolled at a reduction rate of 30 to 40%;
A fifth stage in which the first cold-rolled material in the fourth stage is subjected to a secondary intermediate vacuum heat treatment at 560 to 580 ° C. for 2 to 3 hours, followed by a second cold rolling at a reduction rate of 50 to 60%; ,
A sixth step of subjecting the rolled material secondarily cold-rolled in the fifth step to a third intermediate vacuum heat treatment at 560 to 580 ° C. for 2 to 3 hours, followed by a third cold rolling at a reduction rate of 30 to 40%; ,
And a seventh step of subjecting the rolled material that has been third cold rolled in the sixth step to a final vacuum heat treatment at 440 to 650 ° C. for 7 to 9 hours.   6. The zirconium alloy according to claim 5, wherein phosphorus in the first stage is 0.02 to 0.07 wt%, and a temperature of the final vacuum heat treatment in the seventh stage is 460 to 600 ° C. 6. Production method.   The zirconium alloy according to claim 5, wherein 0.01 to 0.15% by weight of tantalum (Ta) is further added to the mixture in the first stage.   The zirconium alloy according to claim 7, wherein the tantalum (Ta) is 0.03 to 0.1 wt%, and the temperature of the final vacuum heat treatment in the seventh stage is 460 to 530 ° C. Production method.   The method for producing a zirconium alloy according to any one of claims 5 to 9, wherein the phosphorus is compacted before the mixture is dissolved in the first stage.

Images