Sn / Mg micro-alloyed ultra-high strength conductive copper-titanium alloy and preparation method thereof

Abstract

The application relates to the technical field of beryllium-free copper alloy materials, in particular to a Sn / Mg micro-alloyed super-high-strength conductive copper-titanium alloy and a preparation method thereof. The Sn / Mg micro-alloyed super-high-strength conductive copper-titanium alloy comprises the following elements: Ti 2-5%, Sn 0.1-3%, Mg 0.1-3%, and the balance of Cu and inevitable impurities. The Sn / Mg micro-alloyed super-high-strength conductive copper-titanium alloy has a hardness of greater than or equal to 300 HV, an electric conductivity of greater than or equal to 26% IACS, and a tensile strength of greater than or equal to 1000 MPa, and has outstanding comprehensive performance, high strength and high electric conductivity.

Description

Technical Field

[0001] This invention relates to the field of beryllium-free copper alloy materials technology, and in particular to a Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy and its preparation method. Background Technology

[0002] Copper-beryllium alloys are widely used in electronic components and various precision instruments due to their high strength and good electrical conductivity. However, after fully recognizing the serious health and environmental hazards of copper-beryllium alloys in production, people have begun to seek alternative materials such as beryllium bronze.

[0003] Copper-titanium alloys are typical precipitation-hardening alloys, with mechanical properties comparable to copper-beryllium alloys, but lower electrical conductivity. To improve conductivity while maintaining the mechanical properties of copper-titanium alloys, existing technologies propose adding different trace elements and using the synergistic effects of plastic deformation and heat treatment to enhance material properties. For example, patent CN202110203008.8 discloses a copper-titanium alloy with high strength, high plasticity, and bending requirements, and its preparation method; patent CN201910261814.3 discloses a copper-titanium alloy with high hardness, high toughness, and good brittleness and thermal conductivity, and its preparation method; and patent CN202010620874.2 discloses a copper-titanium alloy with high strength and high plasticity, and its preparation method. However, these patents are not ideal in balancing the strength and conductivity of the material. Therefore, a method that can ensure the high strength of copper-titanium alloys while improving their conductivity is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to provide an ultra-high strength and high conductivity copper-titanium alloy with Sn / Mg microalloying, which has high strength and high conductivity.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy, wherein the elemental composition of the conductive copper-titanium alloy includes 2-5% Ti, 0.1-3% Sn, 0.1-3% Mg, with the balance being Cu and unavoidable impurities.

[0007] The preparation method of this conductive copper-titanium alloy includes the following steps:

[0008] S1 Prepare raw materials and vacuum induction melt Cu-Ti-Mg-Sn alloy ingots;

[0009] S2 involves multiple hot rolling processes on the as-cast alloy at a holding temperature of 650–750°C, with a deformation of 50–70%, followed by air cooling. S3 involves solution treatment on the hot-rolled alloy plate at a holding temperature of 750–850°C, followed by water cooling at room temperature. After solution treatment, a first cold rolling process is performed, with a deformation of 50–70%, to obtain a copper-titanium alloy plate.

[0010] The CuSn3Ti5 phase appeared after cold rolling, which improved the electrical conductivity of the alloy; the defects introduced by cold rolling, such as dislocations, provided the driving force for subsequent aging precipitation.

[0011] S4 is used to age copper-titanium alloy plates at 380℃±10℃ for 0.5~100h, followed by air cooling;

[0012] S5 alloy is subjected to a second cold rolling, with a cold rolling deformation of 50-70%;

[0013] S6 subjected the alloy obtained from the second cold rolling to an aging treatment at 350℃±10℃ for 0.5~100h to obtain an ultra-high strength conductive copper-titanium alloy.

[0014] In step S4 of the preparation method of the Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy of this invention, experimental verification showed that the strength was best when the aging time was short, but the electrical conductivity was not high. With the extension of the aging time, the hardness, strength, and electrical conductivity all showed significant improvement. The possible reason is that the number and size of the precipitated phases increased with the extension of the aging time. Specifically, the precipitation of CuSn3Ti5 phase increased, Mg element was uniformly distributed in the copper matrix, and α-Cu4Ti phase was dispersedly precipitated. After the second cold rolling, the material obtained was tested and found that the hardness and strength were improved, with the hardness rising to 300 HV and the tensile strength rising to 1050 MPa. The electrical conductivity only decreased slightly, still maintaining a high electrical conductivity of 21% IACS.

[0015] As a preferred option, S1 is as follows: According to the formula amount, Cu is first added to a vacuum induction furnace for melting at a melting temperature of 1250℃±50℃. After argon gas is introduced, Ti is added, and the mixture is stirred thoroughly. After refining for 20-25 minutes, Sn and Mg are added to the melt in sequence, and the mixture is stirred thoroughly before casting at a casting temperature of 1150℃±50℃.

[0016] Preferably, in S2, hot rolling is performed at a holding temperature of 720℃~740℃ for 2.5~3.5h, with a deformation of 60%~65%. More preferably, hot rolling is performed at a holding temperature of 730℃ for 3h, with a deformation of 60%.

[0017] As a preferred option, the hot-rolled alloy plate in S3 is solution treated at 780-800℃ and held for 3-4 hours.

[0018] Preferably, the deformation amount of the first cold rolling of S3 is 55-65%.

[0019] Preferably, the deformation amount of the second cold rolling of S5 is 50-55%.

[0020] Preferably, the aging time for S4 and S6 is 90h to 100h. The optimal aging parameters after the first cold rolling are 380℃ for 100h and 350℃ for 100h.

[0021] Preferably, the elemental composition of the conductive copper-titanium alloy includes 3% Ti, 0.5-1% Sn, 0.5% Mg, with the balance being Cu and unavoidable impurities.

[0022] A method for preparing a Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy, comprising the following steps:

[0023] S1 Prepare raw materials and vacuum induction melt Cu-Ti-Mg-Sn alloy ingots;

[0024] S2 involves multiple hot rolling processes on the as-cast alloy at a holding temperature of 650–750°C, with a deformation of 50–70%, followed by air cooling. S3 involves solution treatment on the hot-rolled alloy plate at a holding temperature of 750–850°C, followed by water cooling at room temperature. After solution treatment, a first cold rolling process is performed, with a deformation of 50–70%, to obtain a copper-titanium alloy plate.

[0025] After cold rolling, CuSn3Ti5 intermetallic compounds appeared, which improved the electrical conductivity of the alloy; defects introduced by cold rolling, such as dislocations, provided a driving force for subsequent aging precipitation.

[0026] S4 is used to age copper-titanium alloy plates at 380℃±10℃ for 0.5~100h, followed by room temperature water quenching.

[0027] S5 alloy is subjected to a second cold rolling, with a cold rolling deformation of 50-70%;

[0028] S6 subjected the alloy obtained from the second cold rolling to an aging treatment at 350℃±10℃ for 0.5~100h to obtain an ultra-high strength conductive copper-titanium alloy.

[0029] The beneficial effects of this invention are:

[0030] Based on the binary Cu-Ti alloy, this invention improves the strength and conductivity of the Cu-Ti alloy by adding alloying elements and performing multi-stage thermomechanical treatment. Mg is dissolved in the matrix, providing solid solution strengthening; Sn and Ti form the CuSn3Ti5 phase during aging, reducing the dissolved Ti content and increasing the alloy's conductivity; simultaneously, the aging process increases the volume fraction of α-Cu4Ti precipitates, further enhancing the alloy's strength and conductivity. The Sn / Mg microalloyed ultra-high strength and conductive copper-titanium alloy of this invention exhibits a hardness ≥300 HV, conductivity ≥26% IACS, and tensile strength ≥1000 MPa, demonstrating outstanding comprehensive performance with high strength and high conductivity. Attached Figure Description

[0031] Figure 1 The images are metallographic images of (a) Cu-3Ti alloy, (b) Cu-3Ti-0.5Mg-0.5Sn alloy, and (c) Cu-3Ti-0.5Mg-1Sn alloy.

[0032] Figure 2 The hardness and electrical conductivity curves of Cu-3Ti-0.5Mg-0.5Sn alloy after a single cold rolling and aging process are shown.

[0033] Figure 3 The XRD patterns of Cu-3Ti-0.5Mg-0.5Sn alloy after one cold rolling and aging at 380℃ for different times are shown.

[0034] Figure 4 The image is a TEM image of a Cu-3Ti-0.5Mg-0.5Sn alloy after a single cold rolling process and aging at 380℃ for 100 hours.

[0035] Figure 5 The hardness and electrical conductivity curves of Cu-3Ti-0.5Mg-0.5Sn alloy after secondary cold rolling and aging are shown.

[0036] Figure 6 The images show the transmission electron spectroscopy (TEM) patterns of Cu-3Ti-0.5Mg-0.5Sn alloy after secondary cold rolling and aging at 350℃ for (a) 2 hours and (c) 100 hours, and the selected area electron diffraction (SAED) patterns for (b) 2 hours and (d) 100 hours.

[0037] Figure 7 These are the stress-strain curves of Cu-3Ti-0.5Mg-0.5Sn alloy and Cu-3Ti-0.5Mg-1Sn alloy after secondary cold rolling and aging;

[0038] Figure 8 These are the hardness and conductivity curves of a Cu-3Ti-0.5Mg-1Sn alloy after secondary cold rolling and aging. Detailed Implementation

[0039] The technical solution of the present invention will be further described in detail below through specific embodiments. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention.

[0040] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0041] Unless otherwise specified, the reagents used in the following examples can be purchased from a regular biochemical reagent store.

[0042] The core of this invention is to provide an ultra-high strength conductive copper-titanium alloy with Sn / Mg microalloying. The elemental composition of this conductive copper-titanium alloy includes 2-5% Ti, 0.1-3% Sn, 0.1-3% Mg, with the balance being Cu and unavoidable impurities. The preparation method of this conductive copper-titanium alloy includes the following steps:

[0043] S1 Prepare raw materials and vacuum induction melt Cu-Ti-Mg-Sn alloy ingots;

[0044] S2 involves hot rolling the as-cast alloy in multiple passes at a holding temperature of 650–750°C, with a deformation of 50–70%, followed by air cooling after hot rolling.

[0045] S3 performs heat treatment at 750-850℃ on hot-rolled alloy plates and then water-cools them at room temperature. After the solution treatment is completed, the first cold rolling is performed with a cold rolling deformation of 50-70% to obtain copper-titanium alloy plates.

[0046] S4 is used to age copper-titanium alloy plates at 380℃±10℃ for 0.5~100h, followed by air cooling;

[0047] S5 alloy is subjected to a second cold rolling, with a cold rolling deformation of 50-70%;

[0048] S6 subjected the alloy obtained from the second cold rolling to an aging treatment at 350℃±10℃ for 0.5~100h to obtain an ultra-high strength conductive copper-titanium alloy.

[0049] The optimal elemental composition of this conductive copper-titanium alloy includes 3% Ti, 0.5-1% Sn, 0.5% Mg, with the balance being Cu and unavoidable impurities.

[0050] The optimal aging parameters after the first cold rolling are 380℃ for 100 hours and 350℃ for 100 hours after the second cold rolling.

[0051] Example 1

[0052] The composition of Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy, by mass percentage, is: Ti 3%, Sn 0.5%, Mg 0.5%, with the balance being copper.

[0053] The preparation method of this Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy:

[0054] (1) First, Cu is added to a vacuum induction furnace for melting at a melting temperature of 1250℃. After argon is introduced, Ti is added and stirred thoroughly. After refining for 20 minutes, Sn and Mg are added to the melt in sequence and stirred thoroughly before casting at a casting temperature of 1150℃. Copper-titanium alloy ingots are obtained by milling.

[0055] The ingot was milled to remove surface defects, and its hardness was measured to be approximately 310 HV, with an electrical conductivity of 9.0% IACS. This represents a hardness increase of approximately 50 HV compared to the Cu-3Ti binary cast alloy.

[0056] Metallographic images of (a) Cu-3Ti alloy, (b) Cu-3Ti-0.5Mg-0.5Sn alloy, and (c) Cu-3Ti-0.5Mg-1Sn alloy are shown below. Figure 1 Observation of the metallographic structure of the as-cast alloy revealed that the dendrite spacing of the multi-component as-cast alloy was smaller than that of the Cu-3Ti binary alloy, providing evidence for the improved strength of the as-cast alloy. Figure 1 As shown.

[0057] (2) The copper-titanium alloy ingot obtained in step (1) is hot rolled at 730°C and held for 3 hours, with a deformation of 60%; then it is solution treated at 800°C and held for 4 hours, cooled at room temperature, and then cold rolled at room temperature, with a deformation of 60% to obtain a copper-titanium alloy plate.

[0058] The CuSn3Ti5 phase appeared after cold rolling, which improved the electrical conductivity of the alloy. Figure 3 , Figure 4 Defects introduced by cold rolling, such as dislocations, provide the driving force for subsequent aging precipitation. Figure 4 ).

[0059] (3) The copper-titanium alloy plate obtained in step (2) is subjected to aging treatment at 380℃ for 100h and then cooled with air;

[0060] from Figure 2It can be seen that the hardness and conductivity of the sample after a single cold rolling and aging process vary significantly with the aging temperature. The hardness of the sample initially increases and then decreases with aging time. The higher the aging temperature, the shorter the time to reach peak hardness. The hardness of the sample reached its peak value of 310 HV, 340 HV, and 337 HV after aging at 500℃ for 0.5 h, 450℃ for 0.5 h, and 380℃ for 1 h, respectively. With the extension of aging time and the increase of aging temperature, the hardness decreases more rapidly. The conductivity of the sample gradually increases with the extension of aging time. In the early stage of aging, the higher the aging temperature, the faster the conductivity increases. In the later stage of aging, the increase in conductivity is slower. After aging at 380℃ for 100 h, the conductivity of the sample reaches 22.3% IACS. After aging at 450℃ for 100 h, the conductivity of the sample reaches 21.2% IACS. Considering both hardness and conductivity, the optimal aging parameters after a single cold rolling process are 380℃ for 100 h.

[0061] from Figure 3 It can be seen that the CuSn3Ti5 phase appears in the cold-rolled sample. With the extension of aging time, in addition to the CuSn3Ti5 phase, the Cu2Mg phase also appears in the alloy.

[0062] Figure 4 Submicron-sized CuSn3Ti5 phases with dislocations can be observed. The presence of dislocations provides the driving force for the formation of precipitates.

[0063] (4) Then, a second cold rolling is performed at room temperature, with a deformation of 50%, to obtain a second cold-rolled copper-titanium alloy plate;

[0064] After cold rolling, the hardness and strength were improved, with the hardness rising to 300HV and the tensile strength rising to 1050MPa. The electrical conductivity only decreased slightly, still maintaining a high electrical conductivity of 21%IACS. (4) The second cold-rolled copper-titanium alloy plate obtained in step (3) was kept at 350℃ for 100h and then air-cooled to obtain an ultra-high strength conductive copper-titanium alloy.

[0065] from Figure 5 It can be seen that after secondary cold rolling, the hardness of the samples aged at 350℃ and 380℃ remains basically unchanged with aging time, while the electrical conductivity gradually increases. The hardness values ​​at the two aging temperatures are not significantly different, but the electrical conductivity at 350℃ is better than that at 380℃. The optimal aging parameter for overall performance is aging at 350℃ for 100 hours.

[0066] from Figure 6 It can be seen that after secondary cold rolling and aging at 350℃ for 2 hours, a large number of nano-sized α-Cu4Ti precipitates appeared in the sample. Furthermore, the number of α-Cu4Ti precipitates increased after aging for 100 hours. The corresponding SAED diagram confirmed the presence of the α-Cu4Ti precipitates. The α-Cu4Ti precipitates improved the strength of the alloy, all exceeding 800 MPa. Figure 7 As shown.

[0067] Example 2

[0068] The Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy has the following composition by mass percentage: Ti 3%, Sn 1%, Mg 0.5%, with the balance being copper. The preparation method of this Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy is the same as in Example 1.

[0069] The hardness and conductivity curves of Cu-3Ti-0.5Mg-0.5Sn alloy (Example 1) and Cu-3Ti-0.5Mg-1Sn alloy (Example 2) after secondary cold rolling and aging are shown below. Figure 2 As shown; the stress-strain curves of Cu-3Ti-0.5Mg-0.5Sn alloy and Cu-3Ti-0.5Mg-1Sn alloy after secondary cold rolling and aging are as follows. Figure 3 As shown. According to Figure 5 , Figure 7 and Figure 8 It can be seen that after secondary cold rolling and aging, the hardness of the alloy is basically maintained at 310HV, the strength is greater than 800MPa, and the electrical conductivity gradually increases. The alloy exhibits the best comprehensive performance after secondary cold rolling and aging at 350℃ for 100h, with a strength greater than 1100MPa and an electrical conductivity greater than 25%IACS.

[0070] Comparative Examples 1-6

[0071] Conductive copper-titanium alloys with different elemental compositions were prepared using the same method as in Example 1, to compare the effects of each component on the properties of the copper-titanium alloys.

[0072] The composition of the copper-titanium alloys prepared in Examples 1-2 and Comparative Examples 1-6 was tested, and the test results are shown in Table 1.

[0073] Table 1. Composition of copper-titanium alloys prepared in Examples 1-2 and Comparative Examples 1-6

[0074]

[0075]

[0076] The hardness, tensile strength, electrical conductivity, and elongation of the copper-titanium alloys prepared in Examples 1-2 and Comparative Examples 1-6 were tested. The test results are shown in Table 2.

[0077] The testing methods for hardness, tensile strength, elongation, and conductivity are GB / T 4340.1-2009, GB / T228.1-2010, and JB / T 13940-2020, respectively.

[0078] Table 2 Hardness, tensile strength, electrical conductivity, and elongation of copper-titanium alloys

[0079]

[0080] As can be seen from the data in Table 2, the ultra-high strength conductive copper-titanium alloy prepared by the preparation method provided by the present invention has high strength and high conductivity. The alloy prepared in Example 1 has a hardness of up to 310 HV, a tensile strength of up to 1150 MPa, and a conductivity of up to 25% IACS, which are outstanding performance.

[0081] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0082] The present invention provides a detailed description of a Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy and its preparation method. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of these examples are merely for the purpose of helping to understand the method and core ideas of the invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy, characterized in that: The elemental composition of this conductive copper-titanium alloy includes Ti 2~5%, Sn 0.1~3%, Mg 0.1~3%, with the balance being Cu and unavoidable impurities; The preparation method of this conductive copper-titanium alloy includes the following steps: S1 Prepare raw materials and vacuum induction melt Cu-Ti-Mg-Sn alloy ingots; S2 involves hot rolling the as-cast alloy at a holding temperature of 650~750℃ in multiple passes, with a deformation of 50~70%, followed by air cooling after hot rolling. S3 performs heat treatment at 750~850℃ and water cooling at room temperature on hot-rolled alloy plates; after the solution treatment is completed, the first cold rolling is performed with a cold rolling deformation of 50~70% to obtain copper-titanium alloy plates. S4 is used to age copper-titanium alloy plates at 380℃±10℃ for 0.5~100h, followed by air cooling; S5 alloy is subjected to a second cold rolling, with a cold rolling deformation of 50-70%; S6 subjected the alloy obtained from the second cold rolling to an aging treatment at 350℃±10℃ for 0.5~100h to obtain an ultra-high strength conductive copper-titanium alloy.

2. The Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy according to claim 1, characterized in that: S1 is as follows: According to the formula, Cu is first added to a vacuum induction furnace for melting at a melting temperature of 1250℃±50℃. After argon is introduced, Ti is added and stirred thoroughly. After refining for 20-25 minutes, Sn and Mg are added to the melt in sequence and stirred thoroughly before casting at a casting temperature of 1150℃±50℃.

3. The Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy according to claim 1, characterized in that: S2 is hot rolled at a holding temperature of 720℃~740℃ for 2.5~3.5h, with a deformation of 60%~65%.

4. The Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy according to claim 1, characterized in that: S3 hot-rolled alloy plates are solution treated at 780~800℃ and held for 3-4 hours.

5. The Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy according to claim 1, characterized in that: The deformation of S3 during the first cold rolling is 55-65%.

6. The Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy according to claim 1, characterized in that: The deformation amount of the second cold rolling of S5 is 50~55%.

7. The Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy according to claim 1, characterized in that: The processing time for S4 and S6 is 90h~100h.

8. The Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy according to claim 1, characterized in that: The elemental composition of this conductive copper-titanium alloy includes Ti 3%, Sn 0.5~1%, Mg 0.5%, with the balance being Cu and unavoidable impurities.

9. A method for preparing a Sn / Mg microalloyed ultra-high strength conductive copper-titanium alloy as described in claim 1, characterized in that... The preparation method of this conductive copper-titanium alloy includes the following steps: S1 Prepare raw materials and vacuum induction melt Cu-Ti-Mg-Sn alloy ingots; S2 involves multiple hot rolling processes at a holding temperature of 650~750℃, with a deformation of 50~70%, followed by air cooling. S3 involves solution treatment at 750~850℃, followed by water cooling at room temperature. After solution treatment, a first cold rolling process is performed with a deformation of 50~70%, yielding a copper-titanium alloy plate. S4 is used to age copper-titanium alloy plates at 380℃±10℃ for 0.5~100h, followed by air cooling; S5 alloy is subjected to a second cold rolling, with a cold rolling deformation of 50-70%; S6 subjected the alloy obtained from the second cold rolling to an aging treatment at 350℃±10℃ for 0.5~100h to obtain an ultra-high strength conductive copper-titanium alloy.

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