JPH0762467A - Dispersion-strengthening type copper alloy and its production - Google Patents

Abstract

PURPOSE:To produce dispersion-strengthening type copper alloy which does not so much lower degree of the vacuum even if used at high vacuum and good in electrical conductivity and mechanical strength. CONSTITUTION:Copper oxide powder, aluminum oxide powder and carbon powder or boron powder are mixed, and after reducing selectively the copper oxide powder in a reductive atmosphere of <=400 deg.C, the powder is formed and a sintered, and the alloy in which the dispersed particles consisting of 1.5-6vol.% aluminum oxide are dispersed uniformly in a copper mother phase, and an oxygen content is solid solution is <=5ppm and at least one kind between carbon and boron is dispersed in >=10ppm and less than 100ppm is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersion-strengthened copper alloy which can be preferably used even in a high vacuum and a method for producing a dispersion-strengthened copper alloy.

[0002]

2. Description of the Related Art In recent years, dispersion-strengthened copper alloys in which dispersed particles such as metal oxides are uniformly dispersed in a copper matrix are widely used in magnetic field generating coils, semiconductor lead frames, welding electrodes, etc. Has been. Further, as a method for producing such a dispersion-strengthened copper alloy, an internal oxidation method in which the additive metal element in the copper alloy powder is selectively oxidized to form dispersed particles of a metal oxide and then sintered, and an oxidation method A selective reduction method in which copper and a metal oxide to be dispersed particles are mixed and then copper oxide is selectively reduced and sintered has been known. In particular, among these, for example, in the dispersion-strengthened copper alloy obtained by the selective reduction method disclosed in JP-A-2-213433, mixing of a metal element or the like into the copper matrix from the metal oxide to be dispersed particles is almost impossible. In addition, the dispersibility of the metal oxide is good, and sufficient properties have already been obtained in terms of electrical conductivity and mechanical strength.

In contrast to such dispersion-strengthened copper alloys, recently, members for gyrotron oscillator tubes used in high vacuum,
It is also expected to be applied to high heat flux members for fusion devices and structural members for high energy accelerators. However, the conventional dispersion-strengthened copper alloy may release gas due to heating under high vacuum, irradiation with high-energy particles, and the like, thereby lowering the vacuum degree of the system and adversely affecting the operation of the equipment.

[0004]

As described above, the conventional dispersion-strengthened copper alloy may release gas due to heating, irradiation of high-energy particles, etc., and is not suitable for use in high vacuum. There was a problem.

In view of the above problems, the present invention does not significantly lower the degree of vacuum even when used in a high vacuum, and has good electrical conductivity and mechanical strength. It is an object of the present invention to provide a method for producing a copper alloy.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a dispersion-strengthened copper alloy in which 0.5 to 6% by volume of dispersed particles are uniformly dispersed in a copper mother phase. A dispersion-strengthened copper alloy having an oxygen solid solution amount of 5 ppm or less and at least one of carbon and boron dispersed in an amount of 10 ppm or more and less than 100 ppm. That is, the dispersion-strengthened copper alloy of the present invention is characterized in that the amount of oxygen solid solution in the copper matrix is extremely small.

As described above, in the dispersion-strengthened copper alloy, the dispersibility of dispersed particles is suppressed while suppressing the solid solution of metal elements and the like in the copper matrix for the purpose of improving electrical conductivity and mechanical strength. Attempts have been made to raise it, and from such a viewpoint, optimum conditions of oxidation or reduction when dispersion-strengthened copper alloy powder is produced by an internal oxidation method or a selective reduction method have also been reported. However, as a result of the present inventors' research, even if the total amount of solid solution elements in the copper matrix phase is small and the dispersibility of the dispersed particles is good, no matter how the dispersion-strengthened copper alloy powder is produced, it is burned. It was found that oxygen is dissolved in the copper matrix phase to some extent in the dispersion-strengthened copper alloy after sintering if it is contaminated with oxygen in the atmosphere before the formation. Based on such knowledge, the present inventors have found that the gas released from a conventional dispersion-strengthened copper alloy under high vacuum is oxygen dissolved in the copper matrix after producing mainly the dispersion-strengthened copper alloy powder. Therefore, the present invention has been completed by confirming that the release of gas under high vacuum is specifically suppressed when the oxygen solid solution amount in the copper matrix is set to 5 ppm or less.

In the present invention, it is preferable that the solid solution amount of elements other than oxygen in the copper matrix is small. Specifically, in the copper matrix, the amount of decrease in electrical conductivity from pure copper is 5% IACS.
It is desirable to control the total amount of solid solution elements so that the total value is within (absolute value of electric resistivity is 1.77 μΩcm or more).

Further, in the dispersion-strengthened copper alloy of the present invention, by dispersing at least one of carbon and boron having a strong deoxidizing ability, an extremely small amount of oxygen which forms a solid solution in the copper matrix can be dissolved under high vacuum. Emission is suppressed. Here, the dispersion amount of at least one of carbon and boron is 10 ppm or more 1
The amount of less than 00 ppm is because when the amount of dispersion is less than 10 ppm, the amount of gas released under high vacuum increases and the amount of dispersion is 1 ppm.
This is because the mechanical strength and workability of the dispersion-strengthened copper alloy obtained when the content is 00 ppm or more decreases. At this time, carbon and boron may be contained alone or in combination with each other. When two kinds of carbon and boron are contained, they are dispersed in the dispersion strengthened copper alloy as boron carbide. It doesn't matter.

In the present invention, the dispersed particles include aluminum oxide, zirconium oxide, titanium oxide, silicon oxide, magnesium oxide, yttrium oxide, chromium oxide, aluminum nitride, silicon nitride, titanium nitride, boron nitride, titanium carbide, boron carbide. Examples include compounds that are more chemically stable than copper oxide in a reducing atmosphere such as titanium boride. Aluminum oxide is particularly preferable, and for this reason, the solid solution amount of aluminum in the copper matrix is preferably 0.04% by weight or less. In the present invention, the dispersion amount of the dispersed particles is 0.5 to 6% by volume is 0.5
If it is less than 6% by volume, sufficient mechanical strength cannot be obtained.
This is because if it exceeds, the electrical conductivity will be reduced and the secondary processing will be difficult.

The particle size of the dispersed particles is preferably 0.1 μm or less, more preferably 0.005 μm or more and 0.05 μm or less from the viewpoint of mechanical strength, ductility, workability, etc. of the dispersion strengthened copper alloy. Further, in the present invention, it is preferable that the area of the copper matrix phase in which dispersed particles do not exist has an average diameter of 0.3 μm or less. This has an average diameter of 0.3 μm.
If it exceeds, the mechanical strength of the obtained dispersion-strengthened copper alloy may be insufficient. Here, a method of calculating the average diameter of the copper matrix phase region in which dispersed particles do not exist will be described. First, a thin-film sample is prepared from a dispersion-strengthened copper alloy sample, and a 100,000-fold photograph of the thin-film sample obtained by a transmission electron microscope is taken. A micrograph at this time is schematically shown in FIG. Next, as shown in FIG. 1, 10 arbitrary points on the photograph other than the dispersed particles 1 are selected, and 10 maximum circles including each point and not including the dispersed particles 1 are drawn (provided that each point is It is not always the center of the circle), but the average value of the diameters of these circles is the average diameter of the region of the copper matrix 2 in which the dispersed particles 1 do not exist.

Next, the method for producing the dispersion strengthened copper alloy of the present invention will be described in detail. First, a copper oxide powder, a raw material powder of dispersed particles that is more chemically stable than copper oxide in a reducing atmosphere, and a deoxidizer powder containing carbon or boron as a main component are prepared. At this time, the copper oxide powder may be any of cuprous oxide (Cu ₂ O), cupric oxide (CuO), and non-stoichiometric copper oxide (CuO _x ). From the viewpoint of uniform dispersion, the particle size is preferably 5 μm or less, and more preferably 1 μm or less.

As the raw material powder of the dispersed particles, one or more kinds of compounds that are more chemically stable than copper oxide in the reducing atmosphere as described above are used. The particle size of the raw material powder of the dispersed particles is preferably 1 μm or less, more preferably 0.1 μm or less from the viewpoint of uniformly dispersing in the copper mother phase.
It is at most 05 μm.

Further, the deoxidizing agent powder is a compound which is easily decomposed into carbon or boron and a gas by heating and remains as an impurity in the dispersion strengthened copper alloy after sintering without deteriorating the characteristics. It is not particularly limited as long as it is present, but carbon powder, boron powder, and boron carbide powder are preferably used. The particle size of the deoxidizer powder is preferably 1 μm or less. This is because if the particle size of the deoxidizer powder is too large, it becomes difficult to reduce the oxygen content in the copper matrix to 5 ppm or less in the obtained dispersion-strengthened copper alloy, and large unreacted particles remain. This is because the mechanical strength may decrease.

Subsequently, the copper oxide powder, the raw material powder for the dispersed particles, and the deoxidizer powder are blended, and then mechanically ground and mixed to prepare a mixed powder. At this time, even if the copper oxide powder, the raw material powder of the dispersed particles and the deoxidizer powder are blended at once,
Further, the copper oxide powder and the raw material powder of the dispersed particles may be first blended and pulverized and mixed, and then the deoxidizer powder may be blended and further pulverized and mixed. Further, after the copper oxide powder and the raw material powder of the dispersed particles are mixed and pulverized and mixed, the deoxidizer powder can be added as a solution of water or an organic solvent such as alcohol or acetone.

Here, the raw material powder of the dispersed particles is mixed in such an amount that 0.5 to 6% by volume of the dispersed particles are dispersed in the reduced copper matrix of the copper oxide powder. Further, the amount of the deoxidizer powder blended should be such that the equivalent ratio to the amount of oxygen mixed in the copper matrix when the deoxidizer powder is not blended in the same manufacturing process is 1.2 to 1.5. It should be set. The reason for this is that if the compounding amount of the deoxidizer powder is too small,
In the obtained dispersion-strengthened copper alloy, it becomes difficult to set the oxygen solid solution amount in the copper matrix to 5 ppm or less, and when the amount of the deoxidizer powder is too large, the amount of unreacted carbon or boron is 10%.
The mechanical strength of the dispersion-strengthened copper alloy, which remains at 0 ppm or more,
This is because the workability may decrease. Specifically, before producing the dispersion-strengthened copper alloy of the present invention to produce a dispersion-strengthened copper alloy without previously blending a deoxidizer powder, the obtained dispersion-strengthened copper alloy in the copper matrix The total amount of solid-solved oxygen and oxygen of precipitated copper oxide is measured, and 1.2 to 1.5 equivalents relative to the measured oxygen amount are used as the compounding amount of the deoxidizer powder.

The crushing and mixing as described above can be carried out by using a known mixing device such as a ball mill or an attritor. At this time, it is preferable that the container and the ball are made of non-metal. This is because when pulverizing and mixing using a metal container or balls, a metal such as iron is mixed in the mixed powder, and the electric conductivity of the obtained dispersion-strengthened copper alloy may be significantly reduced. Because. In addition, the mixed powder has a particle diameter of the raw material powder of copper oxide powder and dispersed particles of 0.0
It is preferable that the powder is prepared so that the particle size of the deoxidizer powder is 5 μm or less and the particle size of the deoxidizer powder is 0.5 μm or less.

Then, the mixed powder is charged into a reducing furnace kept in a reducing atmosphere at 400 ° C. or lower, and the copper oxide powder in the mixed powder is selectively reduced by a reducing gas such as hydrogen. If the mixed powder is heated above 400 ° C, the deoxidizer powder is consumed for the reduction of copper oxide, and then oxygen dissolved in the copper matrix phase due to oxygen contamination from the atmosphere can be sufficiently removed. Therefore, the mixed powder needs to be maintained at a temperature of 400 ° C. or lower. Furthermore, mix powder to 150
It is more preferable to hold at a temperature of not lower than 400C and not higher than 400C.

This reduction is carried out in a reducing atmosphere having a reduction potential such that the copper oxide powder can be reduced to the state of metallic copper and the raw material powder of the dispersed particles is not completely reduced. However, it is not necessary to create a reducing atmosphere having a reduction potential such that the raw material powder of the dispersed particles is not reduced at all. For example, the raw material powder of dispersed particles is TiO ₂
In the case of (1), there is no problem even if it is reduced up to TiO.

Next, the dispersion-strengthened copper alloy powder generated by the reduction is molded into a predetermined shape by a press or the like to form a molded body. Then, the obtained compact is sintered in a reducing atmosphere or an inert atmosphere to produce the dispersion-strengthened copper alloy of the present invention. Here, after the reduction, for example, oxygen mixed in the copper matrix from the atmosphere at the time of forming a molded body reacts with the deoxidizer powder in the dispersion-strengthened copper alloy powder, and most of it is outside the copper matrix. Will be removed. That is, when the deoxidizer powder contains carbon as a main component, oxygen in the copper matrix is released as carbon monoxide or carbon dioxide during sintering, while the deoxidizer powder contains boron as a main component. In such a case, a small amount of oxygen in the copper matrix is dispersed in the dispersion-strengthened copper alloy obtained as boron oxide, but it has almost no effect on its characteristics. Moreover, the carbon and boron in the deoxidizer powder are not consumed in the reaction with oxygen as described above, and as a result, the dispersion-strengthened copper containing at least one of carbon and boron in an amount of 10 ppm or more and less than 100 ppm. An alloy can be obtained.

At this time, the dispersion-strengthened copper alloy powder is molded by hot pressing or hot isostatic pressing (HIP).
Sintering may be performed at the same time, particularly when using a deoxidizer powder containing boron as a main component, hot pressing excellent in mechanical strength of the dispersion-strengthened copper alloy obtained by low temperature sintering,
HIP is preferred. However, when a deoxidizer powder containing carbon as a main component is used, it is necessary to release carbon monoxide or carbon dioxide released during sintering to the outside of the system, and HIP sealed in a metal can or the like Not very good. Also, when sintering is performed by a method other than HIP, it is preferable that the atmosphere at the time of sintering is once a vacuum in order to release carbon monoxide and carbon dioxide to the outside of the system. Further dispersion strengthened copper alloy of the present invention,
It may be used as it is, or may be used after being subjected to secondary processing if necessary.

In the method for producing the dispersion-strengthened copper alloy according to the present invention as described above, the selective reduction method is used for producing the dispersion-strengthened copper alloy powder. Therefore, the deoxidizing agent can be removed from the step of preparing the mixed powder. By blending the powder with the copper oxide powder and the raw material powder of the dispersed particles, the amount of solid solution of oxygen in the copper matrix in the obtained dispersion strengthened copper alloy can be made extremely small. That is, when the dispersion-strengthened copper alloy powder is produced by the internal oxidation method, the deoxidizer powder that inhibits the formation of dispersed particles due to oxidation cannot be blended before the dispersion-strengthened copper alloy powder is produced, and Even if the deoxidizer powder is blended after the type copper alloy powder is produced, it is difficult to mix the deoxidizer powder uniformly and densely, and the effect of preventing solid solution of oxygen after that is small. On the other hand, in the method for producing the dispersion-strengthened copper alloy of the present invention using the selective reduction method, the deoxidizer powder is blended in the mixed powder before the dispersion-strengthened copper alloy powder is generated to make it uniform and dense. As a result, it is possible to sufficiently remove oxygen dissolved in the copper mother phase due to oxygen contamination from the atmosphere. Moreover, the carbon and boron derived from the deoxidizer powder that was not used to remove oxygen are dispersed in the dispersion-strengthened copper alloy as they are, so the high vacuum of solid solution oxygen slightly remaining in the copper matrix phase. It is possible to suppress the emission below.

[0023]

EXAMPLES First, cupric oxide powder having a particle diameter of 1 μm was used as the copper oxide powder, and aluminum oxide powder having a particle diameter of 0.02 μm was used as a raw material powder for the dispersed particles. The compounding amount was such that 2% by volume of dispersed particles were dispersed in the phase, and further carbon powder or boron powder having a particle size of 0.5 μm was added as the deoxidizing agent powder in the compounding amounts shown in Table 1. , 9 kinds of samples were prepared. Subsequently, these mixed powders were dry-pulverized and mixed for 4 days in a ball mill including a container made of aluminum oxide and balls. Then, the obtained mixed powder is put into a boat made of aluminum oxide, reduction is started from 200 ° C. in a mixed gas flow of argon and hydrogen at a total pressure of 1 atm, and the supply of argon is stopped after reaching 400 ° C. And kept in a pure hydrogen stream for 3 hours. After cooling, the generated dispersion-strengthened copper alloy powder is filled in a carbon mold and 400 k at a temperature of 900 ° C. in vacuum.
Hot-press molding was performed at a pressure of g / cm ² to produce a dispersion-strengthened copper alloy.

Next, test pieces were cut out from each of the 9 types of dispersion-strengthened copper alloys obtained, and the amount of oxygen solid solution and the amount of carbon or boron dispersed in the copper matrix were measured, and the electrical conductivity and mechanical properties were measured. An evaluation test was carried out on the presence or absence of cracks and the gas release characteristics when cold rolling was performed to 0.2% proof stress at room temperature as mechanical strength, and as workability to 99%. When measuring the oxygen solid solution amount, the diameter is 6 m.
m and 6 mm long test pieces were heated and melted in a flowing helium atmosphere at a temperature 250 ° C higher than the melting point of copper (1083 ° C) using a carbon crucible, and the amount of carbon monoxide extracted in helium was measured by gas chromatography. Was quantified and converted into oxygen content. However, in Samples 1, 2 and 6 in Table 1, since the amount of oxygen solid solution in the copper matrix is much higher than 5 ppm, the oxygen of the copper oxide precipitated together with the oxygen dissolved in the copper matrix is combined. Have been analyzed. In addition, the gas release characteristics have a diameter of
mm, 4 mm thick test piece is installed in the gas emission characteristic evaluation tester, and the test piece is heated to 500 ° C. for 2 minutes by the high frequency coil provided around the test piece, and the amount of gas released during this period is measured by mass. It was measured and evaluated with an analyzer. The results are also shown in Table 1. Further, in Table 1, regarding the blending amount of the carbon powder or the boron powder of each sample, the oxygen dissolved in the copper matrix and the precipitated oxidation in the dispersion strengthened copper alloy of Sample 1 in which the deoxidizer powder was not blended The equivalent ratio to the total amount of copper and oxygen was calculated. As shown in Table 1, Sample 3, in which the oxygen solid solution amount in the copper matrix is 5 ppm or less and the carbon or boron dispersion amount is 10 ppm or more and less than 100 ppm.
It was confirmed that the dispersion-strengthened copper alloys 4, 7, and 8 had an extremely small amount of gas released, and had good electrical conductivity and mechanical strength.

[0025]

[Table 1]

[0026]

As described in detail above, according to the present invention, the dispersion-strengthened copper alloy does not significantly lower the vacuum degree even when used in a high vacuum and has good electric conductivity and mechanical strength. Can be realized and its industrial value is enormous.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a method of calculating an average diameter of a copper matrix region.

[Explanation of symbols]

 1 ... Dispersed particles, 2 ... Copper mother phase.

Claims (3)

[Claims] 1. A dispersion-strengthened copper alloy in which 0.5 to 6% by volume of dispersed particles are uniformly dispersed in a copper matrix, wherein an oxygen solid solution amount in the copper matrix is 5 ppm or less. And at least one of carbon and boron is 10 ppm or more 100
Dispersion strengthened copper alloy characterized by being dispersed in less than ppm. 2. The dispersed particles are composed of aluminum oxide,
The dispersion-strengthened copper alloy according to claim 1, wherein the solid solution of aluminum in the copper matrix is 0.04% by weight or less. 3. A copper oxide powder, a raw material powder of dispersed particles that are more chemically stable than copper oxide in a reducing atmosphere, and a deoxidizer powder containing carbon or boron as a main component are mixed and mixed. A step of preparing a powder, a step of selectively reducing the copper oxide powder in the mixed powder in a reducing atmosphere of 400 ° C. or less to generate a dispersion strengthened copper alloy powder, and the dispersion strengthened copper alloy powder The method for producing a dispersion-strengthened copper alloy according to claim 1, further comprising a step of sintering to obtain a dispersion-strengthened copper alloy.