JPH0196338A - Manufacture of carbide dispersion-strengthened copper alloy - Google Patents

Abstract

PURPOSE:To manufacture a carbide dispersion-strengthened copper alloy excellent in mechanical strength by mechanically alloying C, and further, Ti, Zr, Mo, Hf, V, Nb, W, Ta, Cr, etc., with Cu and then applying heat treatment to the above so as to finely precipitate and disperse carbides. CONSTITUTION:Cu, C and the elements which do not form solid solutions with Cu or are extremely reduced in the amounts of solid solutions with Cu are blended in powdered state in the prescribed proportions. The resulting powder mixture is mechanically alloyed in an Ar atmosphere by using an attritor, by which a forced solid solution or a uniform mixture is prepared. The above solid solution or mixture is subjected to heat treatment in a temp. range between about 500 deg.C and the neighborhood of the melting point of Cu. By this method, the compounds of C and the elements, such as Ti and Zr, are finely precipitated and dispersed into Cu, by which the carbide dispersion-strengthened copper alloy remarkably improved in mechanical strength, etc., at a temp. in the range from ordinary temp. to high temp. can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a carbide dispersion strengthened copper alloy using a mechanical alloying method.

(Prior art) Dispersion-strengthened alloys, in which particles such as oxides that are stable even at high temperatures are dispersed in a matrix, have long been known as materials that satisfy the three characteristics of heat resistance, high strength, and high electrical conductivity. Ori,
This reinforcement is achieved by uniformly dispersing fine particles of a substance harder than the substrate into the substrate, and second phase particles finely dispersed in the substrate impede the movement of dislocations due to deformation. It is reinforcement.

There are many methods for dispersing dispersed particles in this dispersion-strengthened alloy, including ■powder mixing method, ■internal oxidation method, and ■mechanical alloying method, but the internal oxidation method and mechanical alloying method are particularly effective. It is thought that there is.

By the way, the heat-resistant copper alloy currently used for welding tips and the like refers to AfzO* dispersion-strengthened copper alloy.
b1 It is manufactured by mechanical alloying method.

(a) A method in which a powder obtained by internally oxidizing dilute Cu-AA solid solution alloy powder is molded by hot extrusion or the like.

(b) A method in which copper powder and /1203 powder are mixed and stirred by a mechanical alloying method and then molded by hot extrusion or the like.

(Problems to be Solved by the Invention) However, the above method has the following drawbacks.

According to method (a), the starting material diluted j41J Cu
= A j2 Grain boundaries always exist in solid solution alloys, where particles coarser than those within the grains precipitate, and as a result, the amount of fine precipitates within the grains that contribute to dispersion strengthening decreases, so the strength increases. This results in a decrease in In addition, for boat fishing, the internal oxidation method is not suitable for thick-walled objects due to the characteristics of the internal oxidation phenomenon, so the processing targets are limited to powder, thin plates, thin wires, etc., and it is not possible to manufacture thick-walled parts. However, there is a problem in that some kind of post-processing is required.

On the other hand, according to method (b), it is difficult to obtain Algoz fine enough for dispersion strengthening due to the Orowan mechanism.
is obtained, but it is questionable whether it can be sufficiently uniformly dispersed by the mechanical alloying method.

A common drawback of methods (a) and (b) is that the wettability of Al2O2 and Cu is poor. In addition, / produced by the above methods (11) and (b)
When 1z03 dispersion strengthened alloy is heated at high temperature, Cu and Al2O+ separate due to poor wettability, which appears as pure Cu sweating on the alloy surface, and the hardness of the alloy decreases accordingly. .

This phenomenon is particularly problematic in areas that are locally exposed to high temperatures, such as welding tips.

In order to solve these problems, the present inventor adopted a mechanical alloying method as a cutting-edge technology in this type of research to eliminate grain boundaries, which is a drawback of the internal oxidation method. In order to improve the uniform dispersibility of dispersed particles in the substrate, which is a problem in this method, a subsequent heat treatment (
We have developed an Aβ201 dispersion strengthened alloy in which various particles are dispersed by combining internal oxidation, internal carbonization, internal boronization, etc. That is, as a starting material, pure C
After producing homogeneous Cu-Al-0 solid solution alloy powder by a mechanical alloying method using U powder, Cu-8 mass% AA master alloy, and cuprous oxide (cuzO) powder, the obtained alloy powder was vacuum annealed. (that is, in this case, it becomes internal oxidation) to react with Al and Cu-A1.02
A dispersion-strengthened alloy was prepared (this result was reported in 1982).
(Previously presented at the Spring Meeting of the Japanese Society of Metals).

However, in the dispersion strengthened alloy obtained above, the precipitated A It t 03 particles grew considerably large, and
They aggregated. In addition, since the oxide dispersion strengthened alloy has poor wettability between Cu and AlzOs, it has a strong tendency to separate during heat treatment, resulting in softening. Furthermore, currently,
A similar phenomenon has been observed in commercially available AlltOz dispersion strengthened alloys.

The present invention was invented in view of the above-mentioned problems, and the dispersion particles have better compatibility with Cu than the Cu A1z02 alloy during heat treatment, and the mechanical strength etc. at room temperature to high temperature are dramatically improved. The purpose of this invention is to provide carbide dispersion strengthened copper with improved performance.

(Means for Solving the Problems) The gist of the configuration of the present invention for achieving the above-mentioned objects is as follows: (a) Cu (b) C (c) Ti, Zr, Mo, Hf, V, Nb, W.

A forced solid solution or a homogeneous mixture is created by mechanically alloying an element selected from the group consisting of Ta and Cr, which does not dissolve in Cu or has a very small amount of solid solubility, and then heat-treats it with carbon. (c) A method for producing a carbide dispersion-strengthened copper alloy, characterized by finely precipitating and dispersing a compound with the elements listed in (c).

Hereinafter, the present invention will be specifically explained based on experimental examples.

(Experiment) First, we investigated dispersed particles that are finely precipitated and dispersed in a copper alloy and have good wettability with Cu.

In order to finely disperse the particles, Cu, element A, which does not dissolve in Cu or has a very small amount of solid solution, and element B, which has a strong affinity for element A, are mechanically dispersed. The idea was to create a forced solid solution or a homogeneous mixture by alloying, and then finely precipitate and disperse the compound of element A and element B by heat treatment. In this case, element A is homogeneously mixed or dissolved in solid solution and then heat-treated.
It is thought that it has the effect of increasing the number of precipitated nuclei as compound AB. For this purpose, carbon is selected as element A, and Tis Zr, Mo, Hf, V, Nb5 is selected as element B.
A material selected from the group consisting of W, Ta and Cr was used. The solubility of carbon in copper is O at 1,100°C.
,0001 wt%, and the solubility is practically equal to zero.

Also, the element selected as element B is IV in the periodic table,
, V, and VI.

They generally combine easily with carbon, forming very hard, high-melting-point carbides. These elements IV, vll, and Vl are mostly dissolved in small amounts in copper, for example, except for 4.3 wt% of Ti (eutectic temperature 885°C) and 1.5 wt% of MO. There is little or no solid solution, and the solubility between Cu and carbide is almost zero.

Thus, the carbide particles precipitated and dispersed in the alloy in the above are TiC, ZrCSMow 0% HfC.

Assuming VC,, NbC5WC, TaC and Cr=C3, the volume fraction of precipitated carbides is 1.68.2.50.4
．． 13.10.00 and 20.00 vo1%.

Furthermore, as starting materials pure Cu5Tis Zr, Mo,
Hf, ■, N b s W s T a s Cr and graphite (c) powder, and after mixing these in a predetermined ratio,
2 in an argon atmosphere at 250 rpm with an attritor.
Mechanically alloyed for 0 hours.

Here, Cu-Ti with a carbide volume fraction of 4.13 volχ
The micrographs of FIGS. 1(a) to 1(d) show the structural changes over time accompanying mechanical alloying in the case of the -C system. As is clear from these micrographs, Ti is distributed uniformly over time.

It is clear that this is the case.

In addition, if the results of examining the distribution state of added elements in alloy powder obtained by mechanical alloying for 20 hours using an X-ray microanalyzer are shown as examples of Cu-Ti-C and C-Zr-C systems, the second Figure (a), mountain) is an X-ray photograph (1,000x magnification) showing the surface analysis results of the Cu-Ti-C system;
d+ is an X-ray photograph (1
,000 times), and in particular, (b) and (d) in the same figure are T
The distribution of i and Zr is shown. Note that the carbide volume fraction is 10.00χ in both systems. As is clear from these photographs, it was assumed that the mixture was homogeneously mixed or a solid solution was formed. Furthermore, as a result of measuring the lattice constant by X-ray diffraction, it was observed that the lattice constant of Cu increased, which revealed that a solid solution was formed (however, in the case of W, it did not become a solid solution. )
. When the thus obtained forced solid solution or mixture was heat-treated in a temperature range from about 500° C. to 1083° C., which is the melting point of Cu, very fine carbide particles were uniformly precipitated and dispersed.

Furthermore, after being mechanically alloyed, typical T
A micrograph (100,000 times magnification) of the IC particles is shown in Figure 3 (al), and a selected area diffraction pattern is shown in Figure 3 (b). Also, after being mechanically alloyed, they were vacuum heated at 900°C for 1 hour. A micrograph (100,000 times magnification) of typical ZrC particles precipitated in a Cu-Zr-C alloy is shown in Figure 4 (al), and a selected area diffraction pattern is shown in Figure 4 (b). The precipitate particles were TiC in the Cu-Ti-C system and ZrC in the Cu-Zr-C system.As the treatment temperature decreased,
The precipitated carbide particles became finer.

For example, Cu with a carbide volume fraction of 4.13 vol%
The average grain size of carbides precipitated by vacuum annealing the -Ti-C alloy at 800° C. for 1 hour was 5 to 20 nm.

With current carbide production technology, even the finest carbide is on the order of submicrons (several hundred nanometers), and it is impossible to produce the fine carbide precipitated in this experiment. In this way, a composite material of fine carbon, compound, and Cu was made possible for the first time by combining a mechanochemical reaction through mechanical alloying with a subsequent heat treatment, that is, internal carbonization.

In addition, Fig. 5 (a), (b) - (c) (all micrographs at 1.000x magnification) show Cu-Al-0, Cu-TiC-C and Cu obtained by mechanical alloying.
A SEM image of the surface of the alloy powder when the -Zr-C based alloy is vacuum annealed (heated for 1 hour) is shown. As is clear from each of these photographs, Cu-Ti-C and Cu-Zr-C based alloys exhibit significantly less pure copper perspiration than Cu-Al-0 based, that is, Cu-Al2oz alloys, and the stability of the alloys is lower. was excellent. Note that (a) above has an oxide volume fraction of 4.13
% Cu-Al-0 was vacuum annealed at 700°C for 1 hour, and (b) was Cu-Ti-0 with a carbide volume fraction of 4.13%.
For (c), Cu-Zr-C with a carbide volume fraction of 4.13% was vacuum annealed at 900°C for 1 hour.
It was vacuum annealed at 000°C for 1 hour.

These alloy powders provided by the present invention (for example, C
The graph in FIG. 6 shows the room temperature hardness measurement results of u-Ti-C and Cu-Zr-C which were heated under vacuum at various temperatures for a predetermined period of time. As is clear from this graph,
In particular, in the Cu-Ti-C system, no change in hardness is observed even after heating at 900°C for 74 hours, and the room-temperature hardness of the dispersion-strengthened alloy produced by the present invention only slightly softens as the heat treatment temperature increases. It was clear that it had excellent heat resistance.

(Effects of the Invention) The carbide dispersion-strengthened copper alloy provided by the present invention configured as described above has excellent heat resistance, with room temperature hardness only slightly softening due to the upper limit of heat treatment temperature. Its uses are extremely wide as various heat-resistant structural materials.

[Brief explanation of the drawing]

Fig. 1 T8) to (d) all show structural changes due to mechanical alloying during the experimental process of the present invention (carbide volume fraction 4.
A micrograph showing the metal structure of the Cu-Ti-C system (in the case of the Cu-Ti-C system with 13 vol.
) and Cu-Zr-C (c and d). Ti-C
Micrograph of Tic particles precipitated in the alloy system (100,000x magnification)
, Figure 4 (b) is the same (X-ray photograph showing the selected area diffraction pattern, Figure 4 (a) is the same (X-ray photograph showing the selected area diffraction pattern), after mechanical alloying, 1
Z deposited on Cu-Zr-C alloy heated in vacuum for hours
Micrograph of rC particles (100,000 times); Figure 5 (b) is an X-ray photograph also showing the selected area diffraction pattern; Figure 5 (a) is a Cu-Al-0 alloy obtained by mechanical alloying. A micrograph (1,000x magnification) of the metal structure when the powder was heated in vacuum for 1 hour. Micrograph of metal structure when heated (1,000x),
Figure (c) shows Cu-Z obtained by mechanical alloying method.
A micrograph (1,000x magnification) of the metal structure obtained when r-C alloy powder was heated in vacuum for 1 hour, and Fig. 6 shows the carbide dispersion-strengthened copper alloy (cu-T
2 is a graph showing the measurement results of room temperature hardness when alloy powders (i-C, Cu-Zr-C, etc.) are vacuum heated at various temperatures for a predetermined period of time.

Claims (1)

[Scope of Claims] (a) Cu (b) C (c) selected from the group consisting of Ti, Zr, Mo, Hf, V, Nb, W, Ta and Cr, and does not form a solid solution in Cu; or After creating a forced solid solution or a homogeneous mixture by mechanically alloying elements with very small amounts of solid solution, a compound of carbon and the elements listed in (c) is finely precipitated and dispersed by heat treatment. A method for producing a characteristic carbide dispersion strengthened copper alloy.