Copper-titanium alloy and preparation method thereof

Abstract

The invention relates to a copper-titanium alloy and a preparation method thereof, and belongs to the technical field of copper alloy materials. The preparation method of the copper-titanium alloy comprises the following steps that a copper-titanium alloy blank is sequentially subjected to homogenization treatment, hot rolling, solution treatment, cold rough rolling, first-time aging treatment, cold finish rolling and second-time aging treatment, and the copper-titanium alloy is obtained. According to the preparation method of the copper-titanium alloy, hot rolling and cold rolling are adopted for plate forming, the combined aging process and the pre-aging, cold rolling and aging production process are adopted, and the content of beta '-Cu4Ti phases in the copper-titanium alloy plate is remarkably increased by means of coordination and complementation of all the steps; the copper-titanium alloy can have good electrical conductivity and mechanical performance at the same time.

Description

Technical Field

[0001] The invention relates to a copper-titanium alloy and a preparation method thereof, belonging to the technical field of copper alloy materials. Background Art

[0002] With the rapid development of 5G and the Internet of Everything technology, high-end electronic products are developing in the direction of miniaturization, lightness, and specialization. Therefore, the thickness of the connectors as the signal transmission bridge is getting thinner and thinner, and the contact area is getting smaller and smaller. This puts higher requirements on the strength, conductivity, and plasticity of the connector materials. At present, Cu-Be alloy is the most widely used and most mature elastic copper-based alloy. It has high strength (over 1GPa), elasticity, good fatigue resistance, medium conductivity (20% IACS) and other comprehensive properties. It occupies a dominant position in the field of copper alloys and is known as the "king of non-ferrous elastic materials". However, the production cost of Cu-Be alloy is high, and it will emit toxic and carcinogenic gas Beo during processing, which is not friendly to the human body and the environment. Therefore, Cu-Be alloy is gradually banned from use, and new materials with green and sustainable development need to be developed.

[0003] Since the 1970s, Cu-Ti alloys have received widespread attention. Researchers have found that the mechanical properties of Cu-Ti alloys after aging are comparable to those of Cu-Be alloys. In addition, Ti is abundant in resources, low in cost, and harmless to the human body. Compared with Cu-Be alloys, Cu-Ti alloys have shown better comprehensive advantages in terms of performance, environmental protection, and cost. These advantages determine that Cu-Ti alloys are increasingly widely used in communications, electrical and electronic industries, and can be used as one of the ultra-high-strength elastic-based copper alloys to replace Cu-Be alloys.

[0004] Cu-Ti alloy, like Cu-Be alloy, is a typical aging-hardened copper alloy. In the early stage of aging, it will undergo spinodal decomposition, decomposing the supersaturated solid solution into two phases with the same composition but different structures, namely, Ti-poor phase and Ti-rich phase. After that, the Ti-rich region will undergo segregation and ordering to transform into a fine needle-like continuous precipitation phase β′-Cu4Ti phase, which has a significant strengthening and toughening effect on the Cu-Ti alloy. It is generally believed that the β′-Cu4Ti phase is the main source of the excellent mechanical properties of the Cu-Ti alloy. At the same time, the precipitation of the β′-Cu4Ti phase reduces the Ti content in the Cu matrix, thereby reducing the electron scattering of the alloy and effectively improving the electrical conductivity of the alloy. However, with the extension of the aging time, the fine needle-like precipitation phase β′-Cu4Ti phase will transform into a coarse lamellar precipitation phase Cu3Ti phase, increasing the brittleness of the alloy. This process is often accompanied by an increase in electrical conductivity but a significant decrease in mechanical properties. Researchers call this process "over-aging", so it is very difficult to obtain a copper-titanium alloy with high strength and good electrical conductivity and plasticity.

[0005] At present, the development of most Cu-Ti alloys focuses on the regulation of β′-Cu4Ti phase and the suppression of Cu3Ti phase, aiming to improve the strength and conductivity of Cu-Ti alloys. This has resulted in the neglect of the plasticity of Cu-Ti alloys in current research. Now, for copper-titanium alloys with a strength greater than 1000MPa, their conductivity is mostly below 15%IACS, and their elongation is mostly below 6%. The imbalance in the performance of high-strength Cu-Ti alloys has also led to a great mismatch between their performance requirements and the current rapid development of the electrical, electronic and communications industries, limiting the transformation of copper-titanium alloys into high-end products (especially thinner special-shaped materials), resulting in the current high-end copper-titanium alloys with better comprehensive performance mostly relying on imports. Therefore, it is of great significance to develop copper-titanium alloys with high strength, good conductivity and plasticity. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a copper-titanium alloy, which can solve the problem that the copper-titanium alloy currently prepared cannot take into account both electrical conductivity and mechanical properties.

[0007] Another object of the present invention is to provide a copper-titanium alloy that can solve the problem that the current copper-titanium alloy cannot have both good electrical conductivity and mechanical properties.

[0008] In order to achieve the above objectives, the technical solution adopted by the method for preparing the copper-titanium alloy of the present invention is:

[0009] A preparation method of a copper-titanium alloy comprises the following steps: subjecting a copper-titanium alloy billet to homogenization treatment, hot rolling, solution treatment, cold rough rolling, first aging treatment, cold finish rolling and second aging treatment in sequence to obtain the copper-titanium alloy; the homogenization treatment temperature is 850°C to 900°C, the solution treatment temperature is 880°C to 900°C, the first aging treatment temperature is 480°C to 500°C, the second aging treatment temperature is 300°C to 350°C, and the time is 1 to 4 hours.

[0010] The preparation method of the copper-titanium alloy of the present invention adopts hot rolling + cold rolling for plate forming, adopts a combined aging process and a production process of pre-aging + cold rolling + aging, and utilizes the coordination and complementarity between the steps to significantly increase the content of the β′-Cu4Ti phase in the copper-titanium alloy, so that the copper-titanium alloy can have good electrical conductivity and mechanical properties at the same time.

[0011] Preferably, the homogenization treatment time is 4 h to 6 h.

[0012] Preferably, the solution treatment time is 1 to 1.5 hours.

[0013] Preferably, the first aging treatment lasts for 2 to 4 hours.

[0014] Preferably, hot rolling is performed in multiple times, each hot rolling includes heating treatment and rolling treatment in sequence, the temperature of the heating treatment is 880°C to 900°C, the rolling deformation of the rolling treatment is 10% to 15%; the total deformation of the hot rolling is 60% to 70%.

[0015] Preferably, the heating treatment time is 1 to 2 hours.

[0016] Preferably, the single rolling deformation of the cold rough rolling is 7% to 9%, the total number of cold rough rolling passes is 8 to 10, and the thickness of the cold rough rolled sheet obtained after the cold rough rolling is 2 mm to 3 mm.

[0017] Preferably, the single rolling deformation of cold finishing rolling is 5% to 10%, the total rolling deformation of cold finishing rolling is 50% to 60%, and the thickness of the cold finishing plate obtained by cold finishing rolling is 1 mm to 1.5 mm.

[0018] Preferably, the mass fraction of titanium in the copper-titanium alloy blank is 2-3%, and the remainder is copper.

[0019] The technical solution adopted by the copper-titanium alloy of the present invention is:

[0020] A copper-titanium alloy prepared by the method for preparing the copper-titanium alloy as described above.

[0021] The copper-titanium alloy prepared by the present invention has a high-density β′-Cu4Ti phase, a conductivity of more than 23% IACS, a strength of more than 1 GPa, and an elongation of about 10%.

[0022] The beneficial effects of the present invention are as follows:

[0023] (1) The present invention uses a combined aging process to fully precipitate the Ti element, obtain a high-density β′-Cu4Ti phase, and maintain the strength of the copper-titanium alloy above 1 GPa.

[0024] (2) The present invention solves the problem of low electrical conductivity of conventional high-strength copper-titanium alloys, maintaining the electrical conductivity above 23.5% IACS.

[0025] (3) The present invention solves the problem that the elongation of the conventional high-strength copper-titanium alloy is less than 6%, and maintains the elongation of the alloy at about 10%.

[0026] (4) The present invention achieves control of the alloy structure through coordination between the steps, significantly improving the comprehensive performance of the alloy, so that the copper-titanium alloy has good conductivity and elongation while maintaining high strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1It is a schematic diagram of the curve of the conductivity and hardness of the copper-titanium alloy plate according to the present invention changing with the second aging treatment time;

[0028] Figure 2 Schematic diagram of mechanical properties of copper-titanium alloy plates prepared in Example 1 of the present invention and Comparative Examples 4-6;

[0029] Figure 3 This is a TEM image of the copper-titanium alloy plate prepared in Example 1 of the present invention;

[0030] Figure 4 This is a schematic diagram of the elemental composition analysis results of the copper-titanium alloy plate prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The preparation method of the copper-titanium alloy of the present invention is a pioneering invention. The present invention adopts hot rolling + cold rolling for plate forming, adopts a combined aging process and a production process of pre-aging + cold rolling + aging, and utilizes the coordination and complementarity between the steps to significantly increase the content of the β′-Cu4Ti phase in the copper-titanium alloy plate, so that the copper-titanium alloy plate has good electrical conductivity and mechanical properties at the same time.

[0032] The technical solution of the present invention is described in detail below in conjunction with specific embodiments.

[0033] 1. The specific embodiment of the method for preparing the copper-titanium alloy of the present invention is as follows:

[0034] Example 1

[0035] The method for preparing the copper-titanium alloy of this embodiment specifically comprises the following steps:

[0036] (1) Weigh high-purity sponge Ti (the purity of high-purity sponge Ti is 99.7%) and industrial electrolytic copper (the purity of industrial electrolytic copper is 99.99%).

[0037] (2) The weighed high-purity sponge Ti and industrial electrolytic copper are placed in the melting chamber of a vacuum medium-frequency induction furnace, and then the vacuum melting furnace is evacuated to a vacuum degree of 0.1 Pa, and then filled with inert gas (argon) to make the gas pressure reach 10000 Pa, and then heated to 1200-1400°C to melt the raw materials. After refining for 2 minutes, the temperature is adjusted and cast into ingots to obtain billets.

[0038] (3) The blank is milled flat to remove the oxide scale to obtain a milled flat sheet. The surface of the milled flat sheet is smooth and flat, the thickness is 15 mm, and the mass percentage of Ti element in the milled flat sheet is 3%.

[0039] (4) The milled flat sheet is placed in a box furnace for homogenization treatment. After the homogenization treatment, it is slowly cooled in the furnace to obtain a homogenized sheet. The homogenization treatment temperature is 900°C and the time is 4 hours. The purpose of the homogenization treatment is to eliminate the dendrites of the ingot, that is, segregation, make the structure more uniform, and eliminate the influence of uneven distribution of Ti elements on the alloy.

[0040] (5) The homogenized sheet is subjected to multiple hot rolling in a box furnace and a rolling mill to obtain a rolled sheet; each hot rolling includes a heating treatment and a rolling treatment in sequence, and the heating treatment in each hot rolling is carried out in a box furnace at a temperature of 900°C and a time of 1 hour; the rolling treatment in each hot rolling is carried out in a rolling mill, and the single rolling deformation is 10%; the total deformation of multiple hot rolling is 60%, and the thickness of the obtained rolled sheet is 6 mm.

[0041] (6) The rolled sheet is placed in a box furnace for heating at 880°C for 1.5 hours, and then quickly taken out for cooling (water cooling at room temperature) to complete the solution treatment and obtain a solution treated sheet.

[0042] (7) The solution treated sheet is subjected to rough cold rolling by a rolling mill, with a single rolling deformation of 7-9% and a total of 8 cold rolling passes. After the rough cold rolling is completed, a rough cold rolled sheet is obtained, and the thickness of the rough cold rolled sheet is 2 mm.

[0043] (8) The cold rough-rolled plate is placed in a box furnace and heated up with the furnace. After being kept warm for a certain period of time, it is cooled to complete the first aging treatment and obtain the first aging treated plate. During the first aging treatment, the heating temperature is 500°C and the holding time is 2h.

[0044] (9) After the first aging treatment plate is polished to remove the oxide scale, it is placed in a rolling mill for cold finishing rolling. The single rolling deformation is 5%, the total rolling deformation is 50%, and the cold finishing plate is obtained. The thickness of the cold finishing plate is 1 mm.

[0045] (10) The tubular furnace is heated to a predetermined temperature, and the cold-rolled plate is placed in the tubular furnace for heating, and then taken out for air cooling to complete the second aging treatment to obtain a copper-titanium alloy plate; the heating temperature in the second aging treatment is 350° C. and the time is 2 h.

[0046] Example 2

[0047] The only difference between the method for preparing the copper-titanium alloy of this embodiment and the method for preparing the copper-titanium alloy of Example 1 is that in step (10) of the method for preparing the copper-titanium alloy of this embodiment, the heating time in the second aging treatment is 1 hour.

[0048] Example 3

[0049] The only difference between the method for preparing the copper-titanium alloy of this embodiment and the method for preparing the copper-titanium alloy of Example 1 is that in step (10) of the method for preparing the copper-titanium alloy of this embodiment, the heating time in the second aging treatment is 4 hours.

[0050] Example 4

[0051] The difference between the preparation method of the copper-titanium alloy of this comparative example and the preparation method of the copper-titanium alloy of Example 1 is that in step (10) of the preparation method of the copper-titanium alloy of this comparative example, the heating temperature in the second aging treatment is 300°C.

[0052] Comparative Example 1

[0053] The difference between the preparation method of the copper-titanium alloy of this comparative example and the preparation method of the copper-titanium alloy of Example 1 is that in step (10) of the preparation method of the copper-titanium alloy of this comparative example, the heating temperature in the second aging treatment is 400°C.

[0054] Comparative Example 2

[0055] The difference between the preparation method of the copper-titanium alloy of this comparative example and the preparation method of the copper-titanium alloy of Example 1 is that in step (10) of the preparation method of the copper-titanium alloy of this comparative example, the heating temperature in the second aging treatment is 450°C.

[0056] Comparative Example 3

[0057] The difference between the preparation method of the copper-titanium alloy of this comparative example and the preparation method of the copper-titanium alloy of Example 1 is that in step (10) of the preparation method of the copper-titanium alloy of this comparative example, the heating temperature in the second aging treatment is 300° C. and the time is 8 h.

[0058] Comparative Example 4

[0059] The difference between the preparation method of the copper-titanium alloy of this comparative example and the preparation method of the copper-titanium alloy of Example 1 is that in step (10) of the preparation method of the copper-titanium alloy of this comparative example, the heating temperature in the second aging treatment is 400° C. and the time is 1 hour.

[0060] Comparative Example 5

[0061] The difference between the preparation method of the copper-titanium alloy of this comparative example and the preparation method of the copper-titanium alloy of Example 1 is that in step (10) of the preparation method of the copper-titanium alloy of this comparative example, the heating temperature in the second aging treatment is 450° C. and the time is 0.5 h.

[0062] Comparative Example 6

[0063] The difference between the preparation method of the copper-titanium alloy of this comparative example and the preparation method of the copper-titanium alloy of Example 1 is that in step (8) of the preparation method of the copper-titanium alloy of this comparative example, the heating temperature during the first aging treatment is 450°C.

[0064] Comparative Example 7

[0065] The difference between the preparation method of the copper-titanium alloy of this comparative example and the preparation method of the copper-titanium alloy of Example 1 is that in step (8) of the preparation method of the copper-titanium alloy of this comparative example, the heating temperature during the first aging treatment is 550°C.

[0066] Comparative Example 8

[0067] The difference between the preparation method of the copper-titanium alloy of this comparative example and the preparation method of the copper-titanium alloy of Example 1 is that in step (6) of the preparation method of the copper-titanium alloy of this comparative example, the heating temperature during the solution treatment process is 850°C.

[0068] 2. The specific embodiments of the copper-titanium alloy of the present invention are as follows:

[0069] The copper-titanium alloy of this embodiment is prepared by the copper-titanium alloy preparation method of embodiment 1.

[0070] Experimental Example 1

[0071] In order to investigate the effect of the second aging treatment time on the electrical conductivity and mechanical properties of the copper-titanium alloy plate, the experiment was repeated according to the preparation method of the copper-titanium alloy plate of Example 1, except that the second aging treatment time in step (10) was adjusted to 0 min, 30 min, 60 min, 120 min, 240 min, 360 min, and 480 min. Then, the electrical conductivity and hardness of the prepared copper-titanium alloy plate were tested. The test results are as follows: Figure 1 shown. Figure 1 In the formula, hardness refers to hardness, electrical conductivity refers to electrical conductivity, and Age Time refers to the time of the second aging treatment. Figure 1 It can be seen that with the extension of the second aging treatment time, the conductivity of the copper-titanium alloy sheet gradually increases, and the hardness reaches a peak at 120 minutes.

[0072] Experimental Example 2

[0073] This experimental example is used to test the electrical conductivity and mechanical properties of the copper-titanium alloy plates prepared in each embodiment and comparative example. The electrical conductivity is measured using a Sigma 2008B1 digital eddy current metal conductivity meter. The probe diameter used for the test is φ14 mm. Before the measurement, a standard annealed pure copper sample (conductivity of 58.0 m / amm 2) The instrument was calibrated, and at least 5 different positions of each sample were measured, and then the average value was taken as the measurement result; the hardness was tested using a HVS-1000A digital display Vickers hardness tester, with a load of 500g and a holding time of 10s. At least 5 different positions of each sample were measured, and the average value was taken as the measurement result after the measurement; the tensile test was carried out on a WDW-100D microcomputer-controlled electronic universal testing machine, and the tensile sample was prepared in accordance with the standard sample requirements for copper and copper alloy materials in GB / T 34505-2017. The test results are shown in Table 1. The mechanical properties of the copper-titanium alloy plates prepared in Example 1 and Comparative Examples 4-6 are shown in Table 1. Figure 2 As shown, Figure 2 TensileStrength here means tensile strength, YieldStrength means yield strength, and Elongtion means elongation.

[0074] Table 1 Electrical conductivity and mechanical properties of copper-titanium alloy plates prepared in various embodiments and comparative examples

[0075] Preparation method Element hardness Electrical conductivity tensile strength Yield Strength Elongation Example 1 Cu-3Ti 305.7HV 24.13%IACS 1043MPa 1017MPa 10％ Example 2 Cu-3Ti 294.1HV 23.9%IACS - - - Example 3 Cu-3Ti 298.3HV 24.8%IACS - - - Example 4 Cu-3Ti 299.1HV - - - - Comparative Example 1 Cu-3Ti 281.9HV - - - - Comparative Example 2 Cu-3Ti 275.7HV - - - - Comparative Example 3 Cu-3Ti - - 876MPa 700MPa 2.3％ Comparative Example 4 Cu-3Ti - - 848MPa 724MPa 7.5％ Comparative Example 5 Cu-3Ti - - 851MPa 783MPa 10％ Comparative Example 6 Cu-3Ti - 23.4%IACS 934MPa 900MPa 9％ Comparative Example 7 Cu-3Ti 303.6HV - 905MPa 850MPa 7.5％ Comparative Example 8 Cu-3Ti 304.4HV 23.8%IACS 940MPa 913MPa 10％

[0076] Note: “-” in Table 1 means not tested.

[0077] From Table 1 and Figure 2 It can be seen that the conductivity of the copper-titanium alloy plate prepared by the present invention is always maintained above 23.5% IACS, the hardness is above 294.1 HV, the strength can be maintained above 1 GPa, the elongation can be maintained at about 10%, and the comprehensive performance is relatively good.

[0078] Experimental Example 3

[0079] This experimental example characterizes the microstructure and chemical composition of the copper-titanium alloy sheet prepared in Example 1. The results are as follows Figure 3 and Figure 4 As shown. Figure 3 As shown in the TEM image, the β′-Cu4Ti phase in the copper-titanium alloy sheet has been fully precipitated. Figure 4 for Figure 3 The point scanning results of the precipitated phase in the area circled by the red circle show that the copper-titanium atomic ratio is 4:1, which meets the composition requirements of the β′-Cu4Ti phase.

Claims

1. A method for preparing a copper-titanium alloy, characterized in that: The following steps are involved: The copper-titanium alloy billet is subjected to homogenization treatment, hot rolling, solution treatment, cold rough rolling, first aging treatment, cold finishing rolling and second aging treatment in sequence to obtain the copper-titanium alloy; the homogenization treatment temperature is 850℃~900℃, the solution treatment temperature is 880℃~900℃, the first aging treatment temperature is 480℃~500℃, the second aging treatment temperature is 300℃~350℃, and the time is 1~4h.

2. The method for preparing the copper-titanium alloy according to claim 1, characterized in that: The homogenization treatment time is 4h to 6h.

3. The method for preparing the copper-titanium alloy according to claim 1, characterized in that: The time of the solution treatment is 1 to 1.5 hours.

4. The method for preparing the copper-titanium alloy according to claim 1, characterized in that: The time of the first aging treatment is 2 to 4 hours.

5. The method for preparing the copper-titanium alloy according to claim 1, characterized in that: The hot rolling is carried out in multiple times, each hot rolling includes heating treatment and rolling treatment in sequence, the temperature of the heating treatment is 880℃~900℃, the rolling deformation of the rolling treatment is 10%~15%; the total deformation of the hot rolling is 60%~70%.

6. The method for preparing the copper-titanium alloy according to claim 5, characterized in that: The heating treatment time is 1 to 2 hours.

7. The method for preparing the copper-titanium alloy according to claim 1, characterized in that: The single rolling deformation of the cold rough rolling is 7% to 9%, the total number of cold rough rolling passes is 8 to 10, and the thickness of the cold rough rolled sheet obtained after the cold rough rolling is 2 mm to 3 mm.

8. The method for preparing the copper-titanium alloy according to claim 1, characterized in that: The single rolling deformation of cold finishing rolling is 5% to 10%, the total rolling deformation of cold finishing rolling is 50% to 60%, and the thickness of the cold finishing rolled sheet obtained by cold finishing rolling is 1mm to 1.5mm.

9. The method for preparing a copper-titanium alloy according to any one of claims 1 to 8, characterized in that: The mass fraction of titanium element in the copper-titanium alloy blank is 2-3%, and the balance is copper element.

10. A copper-titanium alloy prepared by the method for preparing a copper-titanium alloy according to any one of claims 1 to 9.

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