High-strength and high-conductivity copper-nickel-tin alloy and preparation method thereof

Abstract

The invention discloses a high-strength and high-conductivity copper-nickel-tin alloy and a preparation method thereof, and relates to the technical field of alloy material preparation. According to the high-strength and high-conductivity copper-nickel-tin alloy and the preparation method thereof, additive manufacturing cellular microstructure design and intermetallic compound precipitation strengthening and deformation induction transformation processes are organically fused, and the alloy is endowed with a unique cellular microstructure through additive manufacturing; preliminary optimization of strength and conductivity is realized from the microscopic level; subsequent hot isostatic pressing, homogenization, cold rolling, aging treatment and other links have a synergistic effect, and the internal structure of the alloy is further finely regulated and controlled through precipitation strengthening and deformation induced transformation, so that the conductivity of the alloy is remarkably improved on the basis of keeping good mechanical properties, and the alloy has good mechanical properties. The material can be well applied to the fields of electronics, electrics and the like which have harsh requirements on the comprehensive performance of the material, and provides reliable material support for high-end equipment manufacturing, advanced electronic product research and development and the like.

Description

Technical Field

[0001] The invention relates to the technical field of alloy material preparation, in particular to a high-strength and high-conductivity copper-nickel-tin alloy and a preparation method thereof. Background Art

[0002] In today's era of rapid technological development, the electronic and electrical fields are undergoing unprecedented profound changes. From portable consumer electronics such as smartphones and tablets, to large infrastructure such as 5G communication base stations and cloud computing data centers, to electric vehicles, high-speed trains, and various electronic and electrical systems in aerospace vehicles, all of them have put forward increasingly stringent requirements on the performance of basic materials.

[0003] As a key basic material, copper-nickel-tin alloy has long played an important role in many fields. The traditional copper-nickel-tin alloy preparation process often focuses on improving the performance of a certain aspect, and it is difficult to take into account the two key indicators of high strength and high conductivity. In the past, for some conventional electrical connectors, only basic conductivity requirements had to be met, and the strength requirements were relatively low, so traditional processes could still cope with it. However, as electronic products continue to develop in the direction of miniaturization, lightweight, and multifunctionality, the integration of internal components is increasing, and the space is becoming more compact. This means that the alloy materials used to connect the various components must not only have excellent conductivity to ensure the efficiency and stability of signal transmission, but also have sufficient mechanical strength to withstand the various stresses generated during assembly and use, and avoid failures caused by material deformation and fracture.

[0004] Take smartphones as an example. Their motherboards are densely packed with numerous tiny chips, capacitors, resistors and other components, which are connected to each other through extremely fine lines and solder joints. If the copper-nickel-tin alloy material used in these connection parts is not strong enough, when the mobile phone is subjected to daily minor collisions, falls, or temperature changes, problems such as cracking of solder joints and loosening of lines may occur, seriously affecting the normal operation of the mobile phone. Similarly, in the field of electric vehicles, the power system needs to transmit huge currents, requiring electrical connectors to have high conductivity to reduce energy loss and improve endurance; at the same time, the vehicle will encounter frequent vibrations, bumps and complex road conditions during driving, which poses a great challenge to the strength of the connectors. Once the connectors are damaged, not only will the power transmission be interrupted, but it may even endanger driving safety.

[0005] Let's look at 5G communication base stations. In order to achieve high-speed, large-capacity data transmission, the high-frequency electronic devices inside them have extremely high requirements for heat dissipation. As a candidate material for heat dissipation structural parts, copper-nickel-tin alloy must rely on high conductivity to quickly conduct heat to prevent heat accumulation from damaging electronic devices; on the other hand, it must also have high strength to support its own structure and adapt to complex installation environments. Copper-nickel-tin alloys under traditional preparation processes are unable to effectively balance strength and conductivity, so they are unable to cope with these high-end application scenarios, greatly limiting the pace of electronic and electrical equipment to further move towards high performance.

[0006] In order to break this dilemma and meet the urgent needs of current and future technological development for the comprehensive performance of materials, it is very necessary to provide a high-strength and high-conductivity copper-nickel-tin alloy to solve the current problem. Summary of the invention

[0007] The present invention provides a high-strength and high-conductivity copper-nickel-tin alloy and a preparation method thereof, which solves the problems raised in the above-mentioned background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A high-strength and high-conductivity copper-nickel-tin alloy, which contains copper (Cu): 80-85%, nickel (Ni): 8-12%, tin (Sn): 4-6%, and a trace amount of rare earth element cerium (Ce): 0.1-0.3%. The addition of rare earth element Ce can refine the grains, purify the grain boundaries, effectively improve the comprehensive performance of the alloy, and lay the foundation for performance improvement under subsequent complex processes.

[0010] A method for preparing a high-strength and high-conductivity copper-nickel-tin alloy comprises the following steps: raw material preparation: accurately weighing Cu, Ni, Sn and Ce raw materials with a purity of more than 99.9% according to the above proportions to ensure the high quality of the raw materials and provide a guarantee for the preparation of high-performance alloys.

[0011] Additive manufacturing blank construction: Laser powder bed fusion technology is used for additive manufacturing. The powder thickness is set to 30-50μm, the laser power is controlled at 150-250W, the scanning speed is 800-1200mm / s, and the scanning strategy uses a checkerboard or stripe type to ensure uniform energy distribution. In this process, the alloy powder melts and solidifies layer by layer to form a blank with a unique cellular microstructure. In this cellular microstructure, a microstructural feature that is closely integrated with the matrix and is conducive to conductivity and strengthening will be formed under a similar principle. It can not only improve the strength by hindering dislocation movement, but also retain a longer free path for conductive electrons, and initially lay the foundation for high strength and high conductivity. In addition, the particle size distribution of the alloy powder used is 15-45μm to ensure good fluidity and spreadability of the powder, which is conducive to the formation of a uniform and regular cellular microstructure.

[0012] Hot isostatic pressing (HIP): The green body obtained by additive manufacturing is subjected to hot isostatic pressing, with the pressure set to 100-150MPa, the temperature to 900-1000℃, and the holding time to 2-3h. This step is carried out under an inert gas (argon or helium) protective atmosphere to prevent oxidation of the green body under high temperature and high pressure environment and ensure the quality of the green body. Hot isostatic pressing is intended to eliminate the internal pores generated during the additive manufacturing process, improve the density of the green body, further optimize the microstructure, make the cellular microstructure more regular and stable, and provide good conditions for the implementation of subsequent processes.

[0013] Homogenization treatment: Place the HIP-treated billet in a resistance furnace, keep it at 800-850℃ for 6-8h, then cool it to below 300℃, and air-cool it. The purpose is to eliminate the component segregation caused by solidification and previous processing, make the alloy composition uniform, stabilize the internal structure, avoid stress concentration caused by uneven composition, and improve the overall strength. After the homogenization treatment step, the billet is surface treated by mechanical grinding combined with chemical pickling to remove the oxide layer and impurities on the billet surface, ensure the smooth progress of the subsequent cold rolling process, and improve the cold rolling effect.

[0014] Deformation Induction and Precipitation Strengthening Treatment:

[0015] Cold rolling: The homogenized billet is cold rolled, and the deformation is controlled at 40-60%. The surface roughness of the roller of the cold rolling equipment is controlled at Ra0.8-Ra1.6μm to reduce the friction coefficient between the roller and the billet, avoid damage to the billet surface, and ensure the uniformity of cold rolling deformation. During the cold rolling process, the externally applied stress causes the internal crystal structure of the alloy to transform to a phase that is more conducive to strength improvement, while introducing a large number of dislocations to create conditions for subsequent precipitation strengthening.

[0016] Aging treatment: Aging treatment at 400-450℃ for 2-3h, so that some elements in the alloy (such as Ni, Al, etc., which can be precisely adjusted as needed during the initial composition design) will interact with each other to form high-density intermetallic compound nano-precipitates, such as Ni 3 Al, etc. These precipitates are evenly distributed in the alloy matrix, becoming an effective barrier to dislocation slip and improving the strength of the alloy; on the other hand, the new phase induced by deformation is further stabilized at the aging temperature, strengthening the phase interface, and prompting more solute atoms to gather at defects such as dislocations, again hindering dislocation movement, further strengthening the alloy, and optimizing the electrical conductivity. After the aging treatment step, the alloy is subjected to a secondary annealing treatment at a temperature of 300-350°C and an annealing time of 1-2h to further eliminate the residual stress inside the alloy, stabilize the alloy structure, and fine-tune the electrical conductivity while maintaining high strength to meet the needs of different application scenarios.

[0017] The present invention has the following benefits: The present invention organically integrates the design of additive manufacturing cellular microstructure with the precipitation strengthening and deformation induced transformation process of intermetallic compounds. Additive manufacturing gives the alloy a unique cellular microstructure, achieving preliminary optimization of strength and conductivity from a microscopic level; the subsequent hot isostatic pressing, homogenization, cold rolling and aging treatment work synergistically, further fine-tuning the internal structure of the alloy through precipitation strengthening and deformation induced transformation, and fully tapping the potential of the alloy, so that the electrical conductivity of the alloy is significantly improved while maintaining good mechanical properties (tensile strength is greatly improved), which can be well applied to fields such as electronics and electrical engineering that have strict requirements on the comprehensive performance of materials, and provide reliable material support for high-end equipment manufacturing, advanced electronic product research and development, etc. DETAILED DESCRIPTION

[0018] The following is a description of the preferred embodiments of the present invention. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0019] Embodiment 1:

[0020] Weigh Cu80%, Ni12%, Sn6% and Ce0.3% according to weight percentage.

[0021] The preparation process is as follows:

[0022] Raw material preparation: Accurately weigh high-purity raw materials.

[0023] Additive manufacturing body construction: Laser powder bed fusion technology is used, the powder thickness is 30μm, the laser power is 150W, the scanning speed is 800mm / s, the scanning strategy is checkerboard format, and the alloy powder particle size is 15μm.

[0024] Hot isostatic pressing treatment: under argon protection, pressure 100MPa, temperature 900℃, keep warm for 2h.

[0025] Homogenization treatment: keep at 800℃ for 6h, cool down to below 300℃, then air cool out of the furnace, and then carry out mechanical grinding and chemical pickling.

[0026] Deformation induction and precipitation strengthening treatment: cold rolling deformation 40%, roller surface roughness Ra0.8μm; aging treatment at 400℃ for 2h, and finally annealing at 300℃ for 1h.

[0027] After testing, the tensile strength of the obtained alloy reached 720 MPa, and the electrical conductivity reached 53% IACS (International Annealed Copper Standard).

[0028] Embodiment 2:

[0029] Weigh Cu82%, Ni10%, Sn5% and Ce0.2% according to weight percentage.

[0030] Preparation process:

[0031] Raw material preparation: same as Example 1.

[0032] Additive manufacturing body construction: powder thickness 40μm, laser power 200W, scanning speed 1000mm / s, scanning strategy is stripe type, alloy powder particle size 30μm.

[0033] Hot isostatic pressing treatment: helium protection, pressure 120MPa, temperature 950℃, insulation for 2.5h.

[0034] Homogenization treatment: keep at 825℃ for 7h, cool to below 300℃, take out of the furnace and air cool, surface treatment is the same as in Example 1.

[0035] Deformation induction and precipitation strengthening treatment: cold rolling deformation 50%, roller surface roughness Ra1.2μm; aging treatment at 425℃ for 2.5h, annealing at 325℃ for 1.5h.

[0036] Test results: tensile strength 780MPa, electrical conductivity 58%IACS.

[0037] Embodiment 3:

[0038] Weigh Cu85%, Ni8%, Sn4% and Ce0.1% according to weight percentage.

[0039] Preparation steps:

[0040] Raw material preparation: Weigh the raw materials according to the proportion.

[0041] Additive manufacturing body construction: powder thickness 50μm, laser power 250W, scanning speed 1200mm / s, scanning strategy is checkerboard format, alloy powder particle size 45μm.

[0042] Hot isostatic pressing treatment: argon protection, pressure 150MPa, temperature 1000℃, insulation for 3h.

[0043] Homogenization treatment: keep warm at 850℃ for 8h, cool down to below 300℃, then air cool out of the furnace, and perform surface treatment.

[0044] Deformation induction and precipitation strengthening treatment: cold rolling deformation 60%, roller surface roughness Ra1.6μm; aging treatment at 450℃ for 3h, annealing at 350℃ for 2h.

[0045] Performance indicators: tensile strength 750MPa, electrical conductivity 55%IACS.

[0046] Embodiment 4:

[0047] Weigh Cu83%, Ni9%, Sn5% and Ce0.2% according to weight percentage.

[0048] Operation process:

[0049] Raw material preparation: weigh the raw materials accurately.

[0050] Additive manufacturing body construction: powder thickness 35μm, laser power 180W, scanning speed 900mm / s, scanning strategy is stripe type, alloy powder particle size 25μm.

[0051] Hot isostatic pressing treatment: helium protection, pressure 130MPa, temperature 920℃, insulation 2.2h.

[0052] Homogenization treatment: keep at 810℃ for 6.5h, cool down to below 300℃, then air-cool out of the furnace, and perform conventional surface treatment.

[0053] Deformation induction and precipitation strengthening treatment: cold rolling deformation 45%, roller surface roughness Ra1.0μm; aging treatment at 410℃ for 2.2h, annealing at 310℃ for 1.2h.

[0054] After testing: tensile strength 760MPa, electrical conductivity 56%IACS.

[0055] Embodiment 5:

[0056] Weigh Cu84%, Ni11%, Sn4% and Ce0.3% according to weight percentage.

[0057] Preparation process:

[0058] Raw material preparation: Prepare high-purity raw materials.

[0059] Additive manufacturing body construction: powder thickness 45μm, laser power 220W, scanning speed 1100mm / s, scanning strategy is checkerboard format, alloy powder particle size 35μm.

[0060] Hot isostatic pressing treatment: argon protection, pressure 140MPa, temperature 980℃, insulation for 2.8h.

[0061] Homogenization treatment: Keep at 830℃ for 7.5h, cool down to below 300℃, then air cool out of the furnace. Surface treatment is carried out normally.

[0062] Deformation induction and precipitation strengthening treatment: cold rolling deformation 55%, roller surface roughness Ra1.4μm; aging treatment at 430℃ for 2.8h, annealing at 330℃ for 1.8h.

[0063] Experimental data: tensile strength 800MPa, electrical conductivity 59%IACS.

[0064] The experimental data comparison table of each embodiment is as follows:

[0065]

[0066] It can be seen from the comparison table that Example 5 has the best comprehensive performance. While the tensile strength reaches 800 MPa, the electrical conductivity can also reach 59% IACS, which can well meet the stringent requirements of the electronics and electrical fields for high-strength and high-conductivity alloy materials.

[0067] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-strength and high-conductivity copper-nickel-tin alloy, characterized in that: Calculated by weight, the invention comprises 80-85% copper (Cu), 8-12% nickel (Ni), 4-6% tin (Sn), and a trace amount of rare earth element 0.1-0.3% cerium (Ce).

2. The method for preparing a high-strength and high-conductivity copper-nickel-tin alloy according to claim 1, characterized in that: The following steps are involved: Raw material preparation: accurately weigh Cu, Ni, Sn and Ce raw materials with purity above 99.9% according to the ratio described in claim 1; Additive manufacturing body construction: Laser powder bed fusion technology is used for additive manufacturing, the powder thickness is set to 30-50μm, the laser power is controlled at 150-250W, and the scanning speed is 800-1200mm / s; Hot isostatic pressing: The green body obtained by additive manufacturing is subjected to hot isostatic pressing, with the pressure set to 100-150MPa, the temperature to 900-1000°C, and the holding time to 2-3h; Homogenization treatment: Place the hot isostatic pressed green body in a resistance furnace, keep it at 800-850℃ for 6-8h, then cool it down to below 300℃, and air cool it out of the furnace; Deformation Induction and Precipitation Strengthening Treatment: Cold rolling: cold rolling the homogenized blank, with the deformation controlled at 40-60%; Aging treatment: Aging treatment at 400-450℃ for 2-3h.

3. The high-strength and high-conductivity copper-nickel-tin alloy and the preparation method thereof according to claim 2, characterized in that: In the additive manufacturing green body building step, the alloy powder particle size distribution used in the laser powder bed fusion technology is 15-45 μm.

4. The high-strength and high-conductivity copper-nickel-tin alloy and the preparation method thereof according to claim 2, characterized in that: The hot isostatic pressing process is carried out under an inert gas protection atmosphere, and the inert gas is selected from argon or helium.

5. The high-strength and high-conductivity copper-nickel-tin alloy and the preparation method thereof according to claim 2, characterized in that: The inert gas is argon or helium.

6. The high-strength and high-conductivity copper-nickel-tin alloy and the preparation method thereof according to claim 2, characterized in that: After the homogenization step, the surface of the blank is treated by mechanical grinding combined with chemical pickling to remove the oxide layer and impurities on the surface of the blank.

7. The high-strength and high-conductivity copper-nickel-tin alloy and the preparation method thereof according to claim 2, characterized in that: In the cold rolling step, the surface roughness of the rolls of the cold rolling equipment is Ra0.8-Ra1.6μm.

8. The high-strength and high-conductivity copper-nickel-tin alloy and the preparation method thereof according to claim 2, characterized in that: After the aging treatment step, the alloy is subjected to a secondary annealing treatment at a temperature of 300-350°C for 1-2 hours.

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