JPS5854180B2 - High strength and conductive copper alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copper-tin-yttrium alloy that has significantly improved electrical conductivity while maintaining the corrosion resistance, wear resistance, and heat resistance of the copper-tin alloy.

Among the various properties of copper alloys, their excellent corrosion resistance and wear resistance have attracted much attention in recent years.

Copper-tin alloys have been known to meet this demand, and in particular, copper-tin alloys containing 0.5% by weight or more of tin exhibit excellent corrosion resistance and wear resistance.

However, when tin is added to copper, the electrical conductivity is significantly reduced.

The inventors of the present invention previously discovered that by adding yttrium to copper containing solid solution tin, it was possible to improve conductivity while maintaining heat resistance and filed an application (Japanese Patent Application No. 55-109970). ).

In that case, copper alloys were considered as electronic materials that particularly require high conductivity, but the present invention is more concerned with copper alloys as corrosion-resistant and wear-resistant materials, within the range that maintains corrosion resistance and wear resistance. This was the result of systematic research aimed at improving conductivity.

The present inventors have conducted intensive studies on the effect of adding I-IJ to copper alloys containing more than 0.5% by weight and less than 1.0% by weight of tin. Corrosion resistance is achieved by applying yttrium.
It has been found that electrical conductivity can be significantly improved while maintaining wear resistance and heat resistance.

The reason why a highly conductive copper alloy can be obtained by adding yttrium is thought to be because yttrium forms an intermetallic compound with tin.

Up until now, the phase diagram of the tin-IJium alloy has not been reported, and it was unknown whether tin and yttrium form an intermetallic compound. However, when the present invention and others investigated using an and ythtrium were recognized to form intermetallic compounds.

It is believed that the dispersion strengthening effect caused by the formation of an intermetallic compound between tin and yttrium reduces the amount of solid solution tin and improves conductivity without impairing the excellent properties of the copper-filled metal.

In order for yttrium to form an intermetallic compound with tin, yttrium must not be in an oxidized state, so the oxygen content must be low.

The high-strength, high-conductivity copper alloy of the present invention was created based on the above findings, and contains tin exceeding 0.5 weight range and 1.0 weight % or less (0.5<Sn 1 weight %). ,0.1~1.5
Yttrium (0,1<Y<, 1.5% by weight)
), consisting of 0.01515% by weight or less of elemental copper and the balance copper.

The alloys of the present invention contain tin in excess of 0.5% by weight and below the ID weight percent.

If tin is less than 0.5% by weight, it is not sufficient to provide a good combination of corrosion and wear resistance, and if it exceeds to%, the conductivity level will drop below 50% IACS, which is lower than that of yttrium. This is because adding yttrium to restore the level requires a large amount of yttrium, which is impractical in terms of cost.

The alloys of the present invention contain 0.1 to 1.5 yttrium by weight.

The required amount of Inl-IJ depends on the amount of solid solution tin, and if the weight ratio is less than 0.1, the conductivity will not be sufficiently improved due to the large amount of residual solid solution tin, and if it is less than 0.1 If it exceeds the weight percentage, even if all of the solid solute tin is converted into an intermetallic compound, there will still be surplus yttrium, which will become solid solution in the steel, which will tend to reduce the electrical conductivity and reduce the cost. will also be disadvantageous.

The reason why oxygen is limited to 0.015 gravitons is 0.015.
This is because if the amount is increased by 0.15% by weight, the added Inl-IJium is lost as an oxide in the form of ¥203, and the loss rate becomes non-negligible.

Incidentally, 0, O], 5% by weight of oxygen has an atomic number of 9.
4. X]-0-6N (N: Avogadro's number), but all of these oxygen atoms combine with yttrium and
3, the amount of yttrium lost is .

This value assumes that all the existing oxygen is combined with yttrium, but in reality some of the oxygen is combined with Cu.
The amount of yttrium that is lost as oxides decreases accordingly.

In any event, since the alloys of the present invention contain between 0.1 and 15 gravitons of yttrium, the loss of yttrium due to the presence of 0.015 gravitons of oxygen is still sufficient to form intermetallic compounds. Therefore, there is a large amount of yztrium.

Examples of the present invention are shown below.

Example Commercially available electrolytic copper ingots and electrolytic tin were sufficiently coated with charcoal and melted at 1150 to 12500 C, and yttrium was added thereto in the form of a Cu-10% Y master alloy in the required amount.

Then, after deoxidizing by adding 0.01 wt % phosphorus, the ingot was cast into a mold to obtain an ingot with a thickness of 30 mm.

This ingot was face-milled (2 to 3 times on both sides), heated at 800° C. for 1 hour, and hot-rolled to obtain a plate having a thickness of 107n7IL.

Thereafter, it was annealed at 550 to 600°C for 30 minutes, pickled, and then cold rolled to obtain a 2 mm thick plate.

Then, after final annealing at 450'C for 1 hour, pickling and finish rolling were performed to obtain strips with a desired working rate. did.

The composition of each sample is shown in Table 1.

(1) Measurement of electrical conductivity The conductivity was measured using the double bridge method according to the gravimetric method specified in JIS.

(2) Measurement of heat resistance Using a JI No. 85 test piece using an Instron testing machine, 1 for each temperature shown in Table 1 below for materials with a processing rate of 50.
It is expressed as the tensile strength after holding for a certain period of time.

The test results of (1) and (2) are shown in Table-1.

(3) Wear resistance For samples A4 and A5, the amount of wear was measured as a function of time using an Amsler metal wear tester.

The measurement results of (3) are shown in FIG.

In FIG. 1, the ○ mark is the measurement result of sample A4, and the * mark is the measurement result of sample A5.

(4) Measurement of corrosion resistance (stress corrosion test) Matson's solution (0.2mail copper sulfate, 1.0mo
7 ammonium sulfate, 1. The sample size was 100 x 11.5
0”mm, the sample holding method is shown in Figure 2.

In the figure, 1 indicates a sample and 2 indicates a jig.

Stress corrosion resistance was evaluated from the weight loss rate and tensile strength before and after immersion.

The sample results are shown in Table-2.

As is clear from Table 2, the Y-containing alloy has a smaller weight loss rate and is superior in corrosion resistance.

As is clear from the above test results, compared to the conventional copper-tin alloy (sample AI, 4.6), the alloy of the present invention (sample $2p3+5*7) has better heat resistance and wear resistance. It shows a significant improvement in electrical conductivity while maintaining properties and corrosion resistance.

By the way, looking at sample layer 3, all of the 0.64% solid solution tin was converted into an intermetallic compound in the form of Sn Y2 (its existence even requires further research from an academic standpoint). Assuming that, the amount of yttrium required is 0.64 (Xl0-''N)X2 19 Nx89x 102 = 0.96 (wt, %) (However, N represents Avogadro's number.

), which can be said to be close to the value of yttrium in sample A3.

As described above, according to the present invention, by adding yttrium, it is possible to obtain a wear-resistant and corrosion-resistant material having high conductivity, so that a wide range of applications such as trolley wires can be expected.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between wear time and wear amount. FIG. 2 is a side view showing a method of holding a sample for a stress corrosion test.

Claims (1)

[Claims] More than 10.5% by weight and less than 1.0% by weight of tin, 0.1
~1.5% yttrium, 0.01515% by weight
A high-strength, high-conductivity steel alloy consisting of the following elements: