COPPER ALLOY WITH HIGH STRENGTH, HIGH ELECTRICAL CONDUCTIVITY, AND HIGH WEAR RESISTANCE AND PREPARATION METHOD THEREOF

Abstract

The present invention provides a copper alloy with high strength, high electrical conductivity, and high wear resistance and a preparation method thereof. The copper alloy includes 0.7 to 1.5 wt % of Cr, 0.2 to 0.6 wt % Zr and Hf, and Cu as balance. The present invention further discloses a preparation method of the copper, and the method includes the following steps: conducting hot-rolling and then solution treatment, removing a surface oxidation layer, and successively conducting first rolling, first aging treatment, second rolling, and second aging treatment. In the present invention, the preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance can effectively avoid mutual interference between hard second phase particles and alloying elements, and the copper alloy with high strength, high electrical conductivity, and high wear resistance prepared by using the method has excellent wear resistance and mechanical properties.

Description

TECHNICAL FIELD

The present invention relates to metal material technologies, and in particular, to a copper alloy with high strength, high electrical conductivity, and high wear resistance and preparation method thereof.

BACKGROUND

Copper and its alloys have relatively good mechanical properties and electrical conductivity, and therefore are widely applied to the electronic field, the electrical field, the building field, the transportation field, the communication field, the national defense and military industry field, and so on.

The high strength and high electrical conductivity cannot be well balanced at the same time, and it is difficult to simultaneously achieve high strength and high conductivity. Common methods for improving the mechanical properties of materials will degrade their electrical conductivity to some extent. Therefore, balancing a relationship between strength and electrical conductivity becomes one of key problems in the copper processing field. In addition, the wear resistance of a copper alloy directly affects its service life, and improving the wear resistance of the copper alloy can help to prolong its service life and reduce a resource loss. Generally, adding a second phase with high hardness to copper is one of the effective means to improve the wear resistance of materials. Most common hard second phase particles are borides, such as TiB₂, ZrB₂, and HfB₂. However, these borides inevitably interact with alloying elements in the copper alloy, resulting in serious segregation of borides, so as to affect the wear resistance of the materials. In addition, the addition of excessive borides also seriously compromises the electrical conductivity. Meanwhile, it is difficult and challenging to achieve high strength, high electrical conductivity, and high wear resistance simultaneously.

SUMMARY

An objective of the present invention is to prepare a copper alloy with high strength, high conductivity, and high wear resistance in view of a problem that high strength, high conductivity, and high wear resistance of a copper alloy cannot be achieved at the same time currently. The copper alloy can effectively avoid mutual interference between hard second phase particles and alloying elements, and thus has excellent wear resistance and mechanical properties.

To achieve the above purpose, the present invention provides the following technical solutions: A copper alloy with high strength, high electrical conductivity, and high wear resistance includes 0.7 to 1.5 wt % of Cr, 0.2 to 0.6 wt % Zr and Hf, and Cu as balance.

Further, the alloy includes 0.8 to 1.2 wt % of Cr, 0.3 to 0.5 wt % Zr and Hf, and Cu as balance.

Further, the mass ratio of Zr to Hf is 1-1.5.

Further, in the alloy, the Cr element exists in both nano-precipitates Cr and submicron Cr particles.

Further, in the alloy, 50 to 70 wt % of the Cr element exists in a form of nano-precipitates Cr with face-centered cubic structure, and 30 to 50 wt % of the Cr element exists in a form of submicron Cr particles with body-centered cubic structure.

The present invention further provides a preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance, including the following steps:

melting and casting according to a proportion; conducting hot-rolling and then solution treatment, where a solution treatment temperature is 960 to 985° C., and a holding time is 0.5 to 1 h; and conducting water-cooling quenching;

removing a surface oxidation layer, and conducting the first rolling, where a rolling deformation amount is 45 to 75%, and is reduced by 10% each pass, and a rolling temperature is −196 to 30° C.;

conducting the first aging treatment, where an aging temperature is 400 to 450° C., and an aging time is 120 to 150 min;

conducting the second rolling, where a rolling deformation amount is 15 to 45%, and is reduced to less than 10% each pass, a rolling temperature is −196 to 30° C., and a total rolling deformation amount of the first rolling and the second rolling is 80 to 95%; and

conducting second aging treatment, where an aging temperature is 400 to 500° C., and an aging time is 150 to 360 min.

Further, in the first rolling, the rolling deformation amount is 50 to 65%, and is reduced by 10% each pass, and the rolling temperature is −150 to 25° C.

Further, in the first aging treatment, the aging temperature is 400 to 425° C., and an aging time is 120 to 130 min.

Further, in the second rolling, the rolling deformation amount is 25 to 40%, and is reduced to less than 10% each pass, the rolling temperature is −196 to 30° C., and the total rolling deformation amount of the first rolling and the second rolling is 85 to 92%.

Further, in the second aging treatment, the aging temperature is 425 to 475° C., and the aging time is 280 to 360 min.

In the present invention, the copper alloy with high strength, high electrical conductivity, and high wear resistance and a preparation method thereof are provided. Hard Cr particles are introduced to improve the wear resistance of the copper alloy; the nano-precipitates Cr are introduced to enhance mechanical properties of the copper alloy; and this strategy can effectively avoid mutual interference between the hard particles and the alloying elements. Specifically, compared with the prior art, the present invention has the following advantages:

(1) In the present invention, composition design and process optimization are conducted, aging treatment is conducted on a part of Cr elements in Cu—Cr—Zr—Hf alloy to form nano-precipitates Cr; the remaining Cr elements exist in a form of submicron Cr particles. The nano-precipitates Cr enhances strength of the copper alloy, while the submicron Cr particles enhance friction wear resistance of the copper alloy. With the combination of the nano-precipitates Cr and the submicron Cr particles, a Cu—Cr—Zr—Hf alloy plate with high strength, high electrical conductivity, and high wear resistance was prepared via the two-step rolling-aging process.

(2) According to the preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance in the present invention, the prepared Cu—Cr—Zr—Hf alloy has high strength (tensile strength is 705 MPa), high electrical conductivity (79% IACS), and high wear resistance. The copper alloy not only satisfies requirements for high strength and high conductivity in an actual application, but also effectively prolongs the service life of the component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an engineering stress-strain curve of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to Embodiment 1;

FIG. 2 is a comparison diagram of macroscopic wear morphologies of the copper alloys, where figure (a) shows a comparison sample: Cu-0.4% Cr-0.2% Zr-0.2% Hf alloy; and figure (b) shows the copper alloy with high strength, high electrical conductivity, and high wear resistance in Embodiment 1; and

FIG. 3 is an engineering stress-strain curve of a copper alloy with high strength, high electrical conductivity, and high wear resistance according to Embodiment 2.

DETAILED DESCRIPTION

The present invention is further described below with reference to embodiments.

Embodiment 1

This embodiment discloses a copper alloy with high strength, high electrical conductivity, and high wear resistance. The copper alloy includes components at the following weight proportion: 1% Cr, 0.2% Zr, 0.2% Hf, and Cu as balance and is referred to as Cu-1% Cr-0.2% Zr-0.2% Hf.

In this embodiment, a preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance includes the following steps:

preparing the ingots according to the weight proportion; conducting hot-rolling and then solution treatment, where the solution temperature is 972° C., and the holding time is 45 min; and conducting water-cooling quenching;

removing a surface oxidation layer and other defects, and conducting first rolling, where the rolling deformation amount is 60%, and is reduced by 10% each pass, and the rolling temperature is 25° C. (that is, rolling at room temperature);

conducting a first aging treatment, where an aging temperature is 400° C., and an aging time is 120 min;

conducting a second rolling, where the rolling deformation amount is 30%, and is reduced by 10% each pass, a rolling temperature is 25° C., and a total rolling deformation amount of first rolling and second rolling is 90%; and

conducting a second aging treatment, where an aging temperature is 450° C., and an aging time is 300 min.

FIG. 1 is an engineering stress-strain curve of a copper alloy with high strength, high electrical conductivity, and high wear resistance according to Embodiment 1. Specifically,

FIG. 1 is an engineering stress-strain curve of the Cu-1% Cr-0.2% Zr-0.2% Hf alloy prepared through two-step room-temperature (rolling temperature is 25° C.) rolling and aging treatment according to this embodiment. As shown in FIG. 1 and Table 1, the Cu-1% Cr-0.2% Zr-0.2% Hf alloy with yield strength of 613 MPa, tensile strength of 648 MPa, and electrical conductivity of 80.05% IACS is finally prepared in this embodiment. Generally, tensile strength of a common Cu—Cr—Zr alloy is approximately 600 MPa, and overall performance of the sample prepared in this embodiment is higher than that of common Cu—Cr—Zr series alloys. To compare wear resistance, a Cu-0.4% Cr-0.2% Zr-0.2% Hf alloy with the composition outside the range of this embodiment is selected as a comparison sample.

FIG. 2 is a comparison diagram of macroscopic wear morphologies of copper alloys, where figure (a) shows a comparison sample: Cu-0.4% Cr-0.2% Zr-0.2% Hf alloy; and figure (b) shows the copper alloy with high strength, high electrical conductivity, and high wear resistance in Embodiment 1. Specifically, FIG. 2 is a comparison diagram of macroscopic wear morphologies of Cu-1% Cr-0.2% Zr-0.2% Hf alloy and Cu-0.4% Cr-0.2% Zr-0.2% Hf alloy that are both subjected to two-step room-temperature (rolling temperature is 25° C.) rolling and aging treatment in Embodiment 1 in frictional wear experiment conditions: the load is 45N, the sliding speed is 120 mm/s, and the sliding distance is 216 m. FIG. (a) shows the Cu-0.4% Cr-0.2% Zr-0.2% Hf alloy (a comparison sample); and figure (b) shows the sample prepared in specific Embodiment 1. It can be obviously seen from FIG. 2 that, the wear scar diameter of the Cu-1% Cr-0.2% Zr-0.2% Hf alloy prepared in this embodiment is obviously smaller than that of the Cu-0.4% Cr-0.2% Zr-0.2% Hf alloy. This indicates that the wear resistance of the product in this embodiment is greatly improved. Through a calculation, the volume wear loses of the Cu-1% Cr-0.2% Zr-0.2% Hf alloy in this embodiment is 0.05 mm³, while the volume wear loss of the comparison sample is 0.14 mm³. This indicates that wear resistance of the copper alloy is effectively improved in this embodiment. In summary, in this embodiment, a new alloy with high strength, high electrical conductivity, and high wear resistance is prepared.

TABLE 1
Performance of the Cu—1%Cr—0.2%Zr—0.2%Hf
alloy prepared through two-step room-temperature
(rolling temperature is 25° C.) rolling and aging treatment
	Yield strength	Tensile strength	Conductivity
Components	(MPa)	(MPa)	(% IACS)
Cu0.4Cr0.2Zr0.2Hf	613 ± 2	648 ± 4	80.05 ± 0.23

Embodiment 2

This embodiment discloses a copper alloy with high strength, high electrical conductivity, and high wear resistance. The composition of the copper alloy is Cu-1% Cr-0.2% Zr-0.2% Hf.

In this embodiment, a preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance includes the following steps:

conducting hot-rolling and then solution treatment, where the solution temperature is 972° C., and the holding time is 45 min; and conducting water-cooling quenching; removing a surface oxidation layer and other defects, and conducting a first rolling, where the rolling deformation amount is 60%, and is reduced by 10% each pass, and the rolling temperature is −150° C. (that is, rolling at cryogenic temperature);

conducting a first aging treatment, where an aging temperature is 400° C., and an aging time is 120 min;

conducting a second rolling, where a rolling deformation amount is 30%, and is reduced by 10% each pass, a rolling temperature is −150° C. (that is, rolling at cryogenic temperature), and the total rolling deformation amount of the first rolling and second rolling is 90%; and

conducting a second aging treatment, where the aging temperature is 450° C., and the aging time is 300 min.

FIG. 3 is an engineering stress-strain curve of a copper alloy with high strength, high electrical conductivity, and high wear resistance according to Embodiment 2. Specifically, the engineering stress-strain curve is an engineering stress-strain curve of the Cu-1% Cr-0.2% Zr-0.2% Hf alloy prepared through the two-step cryogenic (rolling temperature is −150° C.) rolling and aging treatment in Embodiment 2. As shown in FIG. 3 and Table 2, the Cu-1% Cr-0.2% Zr-0.2% Hf alloy with yield strength of 655 MPa, tensile strength of 705 MPa, and conductivity of 79.00% IACS is finally prepared in this embodiment. Overall performance of the sample prepared in this embodiment is higher than that of common Cu—Cr—Zr series alloys. To compare wear resistance, a Cu-0.4% Cr-0.2% Zr-0.2% Hf alloy with composition outside the range of this embodiment is selected as a comparison sample. Through calculation, the volume wear loss of the Cu-1% Cr-0.2% Zr-0.2% Hf alloy in this embodiment is 0.06 mm³, while the volume wear loss of the comparison sample is 0.13 mm³. This indicates that wear resistance of the copper alloy is effectively improved in this embodiment. In summary, in this embodiment, a new alloy with high strength, high electrical conductivity, and high wear resistance is prepared.

TABLE 2
Performance of the Cu—1%Cr—0.2%Zr—0.2%Hf
alloy prepared through two-step cryogenic (rolling
temperature is −150° C.) rolling and aging treatment
	Yield strength	Tensile strength	Conductivity
Components	(MPa)	(MPa)	(% IACS)
Cu0.4Cr0.2Zr0.2Hf	655 ± 6	705 ± 4	79.00 ± 0.15

Finally, it should be noted that the foregoing embodiments are merely intended for describing the technical solutions of the present invention, but not for limiting the present invention. Although the present invention is described in detail with reference to the foregoing embodiments, persons of ordinary skill in the art should understand that they may still make modifications to the technical solutions described in the foregoing embodiments or make equivalent replacements to some or all technical features thereof, without departing from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A copper alloy with high strength, high electrical conductivity, and high wear resistance, wherein the alloy comprises 0.7 to 1.5 wt % of Cr, 0.2 to 0.6 wt % Zr and Hf, and Cu as balance.

2. The copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 1, wherein the alloy comprises 0.8 to 1.2 wt % of Cr, 0.3 to 0.5 wt % Zr and Hf, and Cu as balance.

3. The copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 1, wherein in the alloy, the Cr element exists in the form of nano-precipitates Cr and submicron Cr particles.

4. The copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 3, wherein in the alloy, 50 to 70 wt % of the Cr element exists in a form of nano-precipitates Cr with face-centered cubic structure, and 30 to 50 wt % of the Cr element exists in a form of submicron Cr particles with body-centered cubic structure.

5. A preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 1, comprising the following steps: melting and casting according to the proportion; conducting hot-rolling and then solution treatment, wherein a solution temperature is 960 to 985° C., and a holding time is 0.5 to 1 h; and conducting water-cooling quenching;removing a surface oxidation layer, and conducting first rolling, wherein a rolling deformation amount is 45 to 75%, and is reduced by 10% each pass, and a rolling temperature is −196 to 30° C.;conducting first aging treatment, wherein an aging temperature is 400 to 450° C., and an aging time is 120 to 150 min;conducting second rolling, wherein a rolling deformation amount is 15 to 45%, and is reduced to less than 10% each pass, a rolling temperature is −196 to 30° C., and a total rolling deformation amount of the first rolling and the second rolling is 80 to 95%; andconducting second aging treatment, wherein an aging temperature is 400 to 500° C., and an aging time is 150 to 360 min.

6. (canceled)

7. (canceled)

8. (canceled)

9. (canceled)

10. A preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 2, comprising the following steps: smelting raw materials according to a proportion; conducting hot-rolling and then solution treatment, wherein a solution temperature is 960 to 985° C., and a holding time is 0.5 to 1 h; and conducting water-cooling quenching;removing a surface oxidation layer, and conducting first rolling, wherein a rolling deformation amount is 45 to 75%, and is reduced by 10% each pass, and a rolling temperature is −196 to 30° C.;conducting first aging treatment, wherein an aging temperature is 400 to 450° C., and an aging time is 120 to 150 min;conducting second rolling, wherein a rolling deformation amount is 15 to 45%, and is reduced to less than 10% each pass, a rolling temperature is −196 to 30° C., and a total rolling deformation amount of the first rolling and the second rolling is 80 to 95%; andconducting second aging treatment, wherein an aging temperature is 400 to 500° C., and an aging time is 150 to 360 min.

11. A preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 3, comprising the following steps: smelting raw materials according to a proportion; conducting hot-rolling and then solution treatment, wherein a solution temperature is 960 to 985° C., and a holding time is 0.5 to 1 h; and conducting water-cooling quenching;removing a surface oxidation layer, and conducting first rolling, wherein a rolling deformation amount is 45 to 75%, and is reduced by 10% each pass, and a rolling temperature is −196 to 30° C.;conducting first aging treatment, wherein an aging temperature is 400 to 450° C., and an aging time is 120 to 150 min;conducting second rolling, wherein a rolling deformation amount is 15 to 45%, and is reduced to less than 10% each pass, a rolling temperature is −196 to 30° C., and a total rolling deformation amount of the first rolling and the second rolling is 80 to 95%; andconducting second aging treatment, wherein an aging temperature is 400 to 500° C., and an aging time is 150 to 360 min.

12. A preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 4, comprising the following steps: smelting raw materials according to a proportion; conducting hot-rolling and then solution treatment, wherein a solution temperature is 960 to 985° C., and a holding time is 0.5 to 1 h; and conducting water-cooling quenching;removing a surface oxidation layer, and conducting a first rolling, wherein a rolling deformation amount is 45 to 75%, and is reduced by 10% each pass, and a rolling temperature ranges from −196 to 30° C.;conducting a first aging treatment, wherein an aging temperature is 400 to 450° C., and an aging time ranges from 120 to 150 min;conducting a second rolling, wherein a rolling deformation amount is 15 to 45%, and is reduced to less than 10% each pass, a rolling temperature is −196 to 30° C., and a total rolling deformation amount of the first rolling and the second rolling is 80 to 95%; andconducting a second aging treatment, wherein an aging temperature is 400 to 500° C., and an aging time is 150 to 360 min.

13. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 5, wherein in the first rolling, the rolling deformation amount is 50 to 65%, and is reduced by 10% each pass, and the rolling temperature is −150 to 25° C.

14. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 10, wherein in the first rolling, the rolling deformation amount is 50 to 65%, and is reduced by 10% each pass, and the rolling temperature is −150 to 25° C.

15. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 11, wherein in the first rolling, the rolling deformation amount is 50 to 65%, and is reduced by 10% each pass, and the rolling temperature is −150 to 25° C.

16. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 12, wherein in the first rolling, the rolling deformation amount is 50 to 65%, and is reduced by 10% each pass, and the rolling temperature is −150 to 25° C.

17. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 5, wherein in the first aging treatment, the aging temperature is 400 to 425° C., and the aging time is 120 to 130 min.

18. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 10, wherein in the first aging treatment, the aging temperature is 400 to 425° C., and the aging time is 120 to 130 min.

19. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 11, wherein in the first aging treatment, the aging temperature is 400 to 425° C., and the aging time is 120 to 130 min.

20. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 12, wherein in the first aging treatment, the aging temperature is 400 to 425° C., and the aging time is 120 to 130 min.

21. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 5, wherein in the second rolling, the rolling deformation amount is 25 to 40%, and is reduced to less than 10% each pass, the rolling temperature is −196 to 30° C., and the total rolling deformation amount of the first rolling and the second rolling is 85 to 92%.

22. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 10, wherein in the second rolling, the rolling deformation amount is 25 to 40%, and is reduced to less than 10% each pass, the rolling temperature is −196 to 30° C., and the total rolling deformation amount of the first rolling and the second rolling is 85 to 92%.

23. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 11, wherein in the second rolling, the rolling deformation amount is 25 to 40%, and is reduced to less than 10% each pass, the rolling temperature is −196 to 30° C., and the total rolling deformation amount of the first rolling and the second rolling is 85 to 92%.

24. The preparation method of the copper alloy with high strength, high electrical conductivity, and high wear resistance according to claim 5, wherein in the second aging treatment, the aging temperature is 425 to 475° C., and the aging time is 280 to 360 min.