Method for simultaneously improving the strength and electrical conductivity of additively manufactured CuCrZr alloy

Abstract

The present invention provides a method for simultaneously improving the strength and electrical conductivity of an additively manufactured CuCrZr alloy. This method belongs to the field of additive manufacturing technology and includes the following steps: Step S1, preparing a defect-free, high-density CuCrZr alloy using additive manufacturing technology; Step S2, heating a muffle furnace or a vacuum heat treatment furnace to 460-700°C, placing the defect-free, high-density CuCrZr alloy in the furnace, and holding the alloy at this temperature for 0.5-12 hours in an air, vacuum, or argon atmosphere; Step S3, cooling the heat-treated, defect-free, high-density CuCrZr alloy after the rated holding time to obtain a CuCrZr alloy with high strength and electrical conductivity. The heat treatment method proposed in the present invention utilizes only a single heat treatment, aiming to ensure that the sample possesses a cellular dislocation structure while simultaneously precipitating a higher number of fine particles, thereby ensuring that the sample has an optimal combination of strength and electrical conductivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and in particular relates to a method for simultaneously improving the strength and electrical conductivity of an additively manufactured CuCrZr alloy. Background Art

[0002] Additive manufacturing (AM), also known as 3D printing, is a process system for producing complex structural parts in a near-net-shape manner. Laser powder bed fusion (LPBF), a type of additive manufacturing technology, is characterized by the direct application of a high-energy heat source to the material, melting and solidifying it layer by layer according to a specific strategy. The main process for LPBF specimen preparation is: 1) constructing a CAD model of the pre-defined component and / or support structure, slicing the component CAD model into a predetermined number of planar layers of a certain thickness, and exporting the data for each layer; 2) determining the LPBF process parameters, scanning strategy, and specific machine configuration based on the pre-specified metal material, and constructing the print file; 3) using the powder spreading component to evenly spread the metal powder onto the substrate according to the thickness of the planar layer; 4) using the laser to act on the metal powder in a specific area of ​​the first layer according to the set scanning strategy, causing it to melt and solidify; 5) the substrate moves downward according to the thickness of one planar layer, and powder is spread again to form the second powder layer; 6) the laser printing, powder spreading, and printing processes are repeated to complete the component preparation. The energy and temperature provided by the laser are sufficient to penetrate a single layer of powder, so each layer of powder can be fused together, thus ensuring the preparation of the component.

[0003] Copper alloys are widely used in the electrical, aerospace, defense, and machinery manufacturing industries due to their high electrical conductivity, excellent thermal conductivity, strong wear resistance, good mechanical properties, and excellent machinability. With the rapid development of industry and the rapid development of science and technology, the performance requirements for copper alloys are becoming increasingly stringent. Specifically, the need to improve the mechanical properties of copper alloys while maintaining high electrical conductivity is a major research focus. CuCrZr alloy is a common solid solution-aged, high-strength, high-conductivity copper alloy. It exhibits high strength, high hardness, excellent thermal conductivity, and good radiation resistance. It is used in railway track contact wires, integrated circuit lead frames, mold linings, and resistance welding electrodes. Generally speaking, there is a trade-off between the strength and electrical conductivity of copper alloys: improving the alloy's strength comes at the expense of its electrical conductivity. Unlike traditional melting and casting processes, LPBF technology features high cooling rates and localized melting and solidification, which inevitably lead to unique microstructures and properties in CuCrZr alloys prepared by LPBF. High cooling rates have an effect similar to solution quenching on LPBF-produced CuCrZr alloys, resulting in a supersaturated solid solution state and, in turn, low electrical conductivity. Furthermore, LPBF-produced CuCrZr alloys also exhibit microstructural features common to laser additively manufactured alloys, such as a cellular subgrain structure with dislocation-entangled boundaries. The LPBF-produced alloys have a relative density of 97.65–99.8%, a strength of 210–305 MPa, a hardness of 70–120 HV, and an electrical conductivity of 15–20% IACS (International Annealed Copper Standard). The electrical conductivity and mechanical properties of LPBF-produced CuCrZr alloys are significantly lower than those of copper alloys produced by conventional methods, with the electrical conductivity failing to reach the industry standard of 20% IACS. In summary, LPBF-produced CuCrZr alloys exhibit low strength and electrical conductivity. Furthermore, the relevant patents do not mention heat treatment methods for simultaneously improving the strength and electrical conductivity of additively manufactured defect-free CuCrZr alloys. Therefore, it is necessary to develop and optimize relevant heat treatment processes to comprehensively improve the performance of CuCrZr alloys. Based on this, the heat treatment method for additively manufactured CuCrZr alloys developed in this invention has very important engineering significance and effectively fills this gap. Summary of the Invention

[0004] The present invention addresses the technical problems of low strength and low conductivity of additively manufactured CuCrZr alloys in the prior art, and provides a method for simultaneously improving the strength and conductivity of additively manufactured CuCrZr alloys. The method can ensure the stable existence of the cellular subgrain structure in the sample, avoid coarsening of the matrix grains, and achieve uniform distribution of fine precipitated particles in the matrix, thereby simultaneously improving the strength and conductivity of the additively manufactured CuCrZr alloy and achieving a good match between strength and conductivity.

[0005] The technical solution adopted by the present invention is: a method for simultaneously improving the strength and electrical conductivity of CuCrZr alloy in additive manufacturing, comprising the following steps:

[0006] Step S1, preparing a defect-free high-density CuCrZr alloy using additive manufacturing technology;

[0007] Step S2, heating the muffle furnace or vacuum heat treatment furnace to 460-700° C., placing the defect-free high-density CuCrZr alloy obtained in step S1 in the furnace, holding the temperature for 0.5-12 hours, and using air, vacuum, or argon as the heat treatment atmosphere;

[0008] Step S3, after the rated holding time, cooling the defect-free high-density CuCrZr alloy after the heat treatment in step S2 to obtain a CuCrZr alloy with high strength and electrical conductivity, wherein the cooling method is furnace cooling or air cooling.

[0009] Furthermore, in step S1, the additive manufacturing technology is laser powder bed melting technology.

[0010] Furthermore, in step S1, the process parameters of the laser powder bed fusion technology are as follows: the laser energy density range is 200~1000J / mm 3 , a defect-free high-density CuCrZr alloy ingot with a density exceeding 99.3% was prepared. Defects refer to defects such as unmelted powder, holes, or cracks.

[0011] Furthermore, in step S2, the time for placing the defect-free high-density CuCrZr alloy into the muffle furnace or vacuum heat treatment furnace is controlled within 1 minute, and the furnace door is closed in time.

[0012] Furthermore, in step S2, the temperature of the muffle furnace or vacuum heat treatment furnace is raised to 500-550° C., and the holding time is 0.5-4 hours.

[0013] Furthermore, in step S3, the cooling rate is 20 to 120°C / s.

[0014] Compared with the prior art, the present invention has the following beneficial effects: the heat treatment method proposed in the present invention uses only one heat treatment, the purpose of which is to ensure that the sample has a cellular dislocation structure while precipitating a higher number of fine particles, thereby ensuring that the sample has the best strength and conductivity combination. The present invention can maintain the stable existence of the cellular subgrain structure in the microstructure, avoid the coarsening of the matrix grain structure and the precipitated particles, and also promote the precipitation of a large number of fine particles. On the one hand, the improvement of the above-mentioned microstructure can weaken the scattering effect of the matrix on electrons, thereby improving the conductivity of the sample; on the other hand, it can enhance the strengthening mechanism of the precipitated particles and ensure the dislocation strengthening mechanism, thereby improving the strength of the sample. The present invention can simultaneously improve the strength and conductivity of the additively manufactured CuCrZr alloy, and provide technical support for the additive manufacturing of high-strength and high-conductivity CuCrZr copper alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The SEM image (a), high-magnification SEM image (b), transmission electron microscope image (c), and tensile curve graph (d) of the CuCrZr alloy prepared in Comparative Example 1 of the present invention are shown;

[0016] Figure 2 The SEM image (a), high-magnification SEM image (b), transmission electron microscope image (c), and tensile curve graph (d) of the CuCrZr alloy prepared in Comparative Example 2 of the present invention are shown;

[0017] Figure 3 The SEM image (a), high-magnification SEM image (b), transmission electron microscope image (c), and tensile curve graph (d) of the CuCrZr alloy prepared in Example 1 of the present invention are shown;

[0018] Figure 4 The SEM image (a), high-magnification SEM image (b), transmission electron microscope image (c), and tensile curve graph (d) of the CuCrZr alloy prepared in Example 2 of the present invention;

[0019] Figure 5 SEM image (a), high magnification SEM image (b), and transmission electron microscope image (c) of the CuCrZr alloy prepared in Example 3 of the present invention;

[0020] Figure 6 High-magnification SEM image (a) and transmission electron microscope image (b) of the CuCrZr alloy prepared in Example 4 of the present invention;

[0021] Figure 7 (a) A high-magnification SEM image and (b) a transmission electron microscope image of the CuCrZr alloy prepared in Example 5 of the present invention. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Comparative Example 1

[0024] In the comparative example of the present invention, a CuCrZr alloy was prepared using laser powder bed fusion technology with a laser energy density of approximately 500 J / mm3. The alloy had no defects such as pores, unmelted powder, or cracks, and had a density of 99.5%.

[0025] Figure 1 (a) and Figure 1 (b) shows the scanning electron microscope microstructure of the laser powder bed melted CuCrZr alloy. It can be seen that the alloy grain structure is irregular in shape with an average size of about 28 μm, and fine precipitated particles are distributed in the alloy. Figure 1 (c) shows the transmission electron microscopy microstructure of the CuCrZr alloy. It can be seen that the alloy has a cellular subgrain structure and dislocations distributed along the boundaries. Figure 1 (d) shows the tensile curve of the CuCrZr alloy, with an ultimate tensile strength of 276 MPa. The electrical conductivity of the alloy was tested, and its conductivity was about 20% IACS.

[0026] Comparative Example 2

[0027] The comparative example of the present invention adopts laser powder bed melting technology to prepare CuCrZr alloy, and the volume energy density used is about 500J / mm 3 The alloy has no defects such as pores, unmelted powder or cracks, and its density is 99.5%.

[0028] The heat treatment system used in this comparative example is the same as that used in the traditional process for preparing CuCrZr alloy. The specific steps are as follows:

[0029] 1) The defect-free, high-density CuCrZr alloy formed by laser powder bed fusion was placed in a muffle furnace at 1000°C for 1 hour and then water-cooled to room temperature;

[0030] 2) The alloy was placed in a muffle furnace at 500°C for 0.5 h, and then air-cooled to room temperature to complete the heat treatment.

[0031] Figure 2 (a) and Figure 2 (b) shows the scanning electron microscopy microstructure of the heat-treated CuCrZr alloy. Compared with Comparative Example 1, the grain structure of the heat-treated CuCrZr alloy is significantly coarsened, with an average size of several hundred microns, and coarse precipitated particles are distributed in the alloy. Figure 2(c) shows the transmission electron microscopy microstructure of the CuCrZr alloy. Compared with Comparative Example 1, it can be seen that there is no cellular subgrain structure and dislocations distributed along the boundaries in the heat-treated CuCrZr alloy. Figure 2 (d) shows the tensile curve of the heat-treated CuCrZr alloy, whose ultimate tensile strength is 206 MPa, which is much lower than that of the CuCrZr alloy in Comparative Example 1. The electrical conductivity of the heat-treated alloy is tested, and its electrical conductivity is about 86% IACS, which is much higher than that of the CuCrZr alloy in Comparative Example 1.

[0032] Example 1

[0033] An embodiment of the present invention provides a method for simultaneously improving the strength and electrical conductivity of an additively manufactured CuCrZr alloy, comprising the following steps:

[0034] Step S1: prepare defect-free high-density CuCrZr alloy using laser powder bed fusion technology, with a laser energy density of about 500 J / mm 3 The defect-free, high-density CuCrZr alloy has no defects such as pores, unmelted powder or cracks, and its density is 99.4%.

[0035] Step S2: placing the defect-free high-density CuCrZr alloy in a muffle furnace at 500° C. and keeping the temperature for 0.5 h in a vacuum atmosphere for heat treatment.

[0036] Step S3: After the rated holding time, the heat-treated defect-free high-density CuCrZr alloy is cooled to room temperature to complete the heat treatment at a cooling rate of 20°C / s to obtain a CuCrZr alloy with high strength and electrical conductivity.

[0037] Figure 3 (a) and Figure 3 (b) shows the scanning electron microscopy microstructure of the heat-treated CuCrZr alloy. The grain structure of the heat-treated CuCrZr alloy remains irregular, with an average size of approximately 20 μm. The grain structure of the heat-treated CuCrZr alloy is the same as that of Comparative Example 1. Compared with Comparative Example 2, the grain size of the heat-treated CuCrZr alloy is finer. Compared with Comparative Example 1, the heat-treated CuCrZr alloy has a higher number of fine precipitated particles. Compared with Comparative Example 2, the heat-treated CuCrZr alloy has finer precipitated particles. Figure 3 (c) shows the scanning electron microscopy microstructure of the heat-treated CuCrZr alloy. The heat-treated CuCrZr alloy has the same cellular subgrain structure and dislocations distributed along the boundaries as those in Comparative Example 1. Figure 3(d) shows the tensile curve of the heat-treated CuCrZr alloy, which exhibits an ultimate tensile strength of 513 MPa, significantly higher than the CuCrZr alloys in Comparative Examples 1 and 2. Electrical conductivity testing of the heat-treated alloy reveals an electrical conductivity of approximately 82% IACS, significantly higher than that of the CuCrZr alloy in Comparative Example 1. Therefore, the CuCrZr alloy prepared in this example exhibits a cellular subgrain structure, a fine grain structure, and a high number of fine precipitated particles, resulting in both high strength and high electrical conductivity.

[0038] Example 2

[0039] An embodiment of the present invention provides a method for simultaneously improving the strength and electrical conductivity of an additively manufactured CuCrZr alloy, comprising the following steps:

[0040] Step S1: prepare defect-free high-density CuCrZr alloy using laser powder bed fusion technology, with a laser energy density of about 1000 J / mm 3 The defect-free, high-density CuCrZr alloy has no defects such as pores, unmelted powder or cracks, and its density is 99.6%.

[0041] Step S2: placing the defect-free high-density CuCrZr alloy in a muffle furnace at 460° C. and keeping the temperature for 0.5 h in a vacuum atmosphere for heat treatment.

[0042] Step S3: After the rated holding time, the heat-treated defect-free high-density CuCrZr alloy is cooled to room temperature to complete the heat treatment at a cooling rate of about 120°C / s to obtain a CuCrZr alloy with high strength and electrical conductivity.

[0043] Figure 4 (a) and Figure 4 (b) shows the scanning electron microscopy microstructure of the heat-treated CuCrZr alloy. The grain structure of the heat-treated CuCrZr alloy remains irregular, with an average size of approximately 20 μm. The grain structure of the heat-treated CuCrZr alloy is the same as that of Comparative Example 1. Compared with Comparative Example 2, the grain size of the heat-treated CuCrZr alloy is finer. Compared with Comparative Example 1, the heat-treated CuCrZr alloy has a higher number of fine precipitated particles. Compared with Comparative Example 2, the heat-treated CuCrZr alloy has finer precipitated particles. Figure 4 (c) shows the scanning electron microscopy microstructure of the heat-treated CuCrZr alloy. The heat-treated CuCrZr alloy has the same cellular subgrain structure and dislocations distributed along the boundaries as those in Comparative Example 1. Figure 4(d) shows the tensile curve of the heat-treated CuCrZr alloy, which exhibits an ultimate tensile strength of 320 MPa, significantly higher than the CuCrZr alloys in Comparative Examples 1 and 2. Electrical conductivity testing of the heat-treated alloy reveals an electrical conductivity of approximately 81% IACS, significantly higher than that of the CuCrZr alloy in Comparative Example 1. Therefore, the CuCrZr alloy prepared in this example exhibits a cellular subgrain structure, a fine grain structure, and a high number of fine precipitated particles, resulting in both high strength and high electrical conductivity.

[0044] Example 3

[0045] An embodiment of the present invention provides a method for simultaneously improving the strength and electrical conductivity of an additively manufactured CuCrZr alloy, comprising the following steps:

[0046] Step S1: prepare defect-free high-density CuCrZr alloy using laser powder bed fusion technology, with a laser energy density of about 200 J / mm 3 The defect-free, high-density CuCrZr alloy has no defects such as pores, unmelted powder or cracks, and its density is 99.6%.

[0047] Step S2: placing the defect-free high-density CuCrZr alloy in a muffle furnace at 700° C. and keeping the temperature for 12 hours in a vacuum atmosphere for heat treatment.

[0048] Step S3: After the rated holding time, the heat-treated defect-free high-density CuCrZr alloy is cooled to room temperature to complete the heat treatment at a cooling rate of about 80°C / s to obtain a CuCrZr alloy with high strength and electrical conductivity.

[0049] Figure 5 (a) and Figure 5 (b) shows the scanning electron microscopy microstructure of the heat-treated CuCrZr alloy. The grain structure of the heat-treated CuCrZr alloy remains irregular, with an average size of approximately 20 μm. The grain structure of the heat-treated CuCrZr alloy is the same as that of Comparative Example 1. Compared with Comparative Example 2, the grain size of the heat-treated CuCrZr alloy is finer. Compared with Comparative Example 1, the heat-treated CuCrZr alloy has a higher number of fine precipitated particles. Compared with Comparative Example 2, the heat-treated CuCrZr alloy has finer precipitated particles. Figure 5(c) shows the transmission electron microscopy microstructure of the heat-treated CuCrZr alloy. The heat-treated CuCrZr alloy has the same cellular subgrain structure and dislocations distributed along the boundaries as those in Comparative Example 1. The ultimate tensile strength of the heat-treated CuCrZr alloy is 410 MPa, which is much higher than that of the CuCrZr alloys in Comparative Example 1 and Comparative Example 2. The electrical conductivity of the heat-treated alloy was tested, and its electrical conductivity was approximately 84% IACS, which is much higher than that of the CuCrZr alloy in Comparative Example 1. Therefore, the CuCrZr alloy prepared by this embodiment has a cellular subgrain structure, a fine grain structure, and a higher number of fine precipitated particles, so that the CuCrZr alloy has high strength and high electrical conductivity.

[0050] Example 4

[0051] An embodiment of the present invention provides a method for simultaneously improving the strength and electrical conductivity of an additively manufactured CuCrZr alloy, comprising the following steps:

[0052] Step S1: prepare defect-free high-density CuCrZr alloy using laser powder bed fusion technology, with a laser energy density of about 400 J / mm 3 The defect-free, high-density CuCrZr alloy has no defects such as pores, unmelted powder or cracks, and its density is 99.4%.

[0053] Step S2: placing the defect-free high-density CuCrZr alloy in a muffle furnace at 600° C. and keeping the temperature for 12 hours in a vacuum atmosphere.

[0054] Step S3: After the rated holding time, the heat-treated defect-free high-density CuCrZr alloy is cooled to room temperature to complete the heat treatment at a cooling rate of about 120°C / s to obtain a CuCrZr alloy with high strength and electrical conductivity.

[0055] Figure 6 (a) shows the scanning electron microscopy microstructure of the heat-treated CuCrZr alloy. The grain structure of the heat-treated CuCrZr alloy is the same as that of Comparative Example 1. Compared with Comparative Example 2, the grain size of the heat-treated CuCrZr alloy is finer. Compared with Comparative Example 1, the heat-treated CuCrZr alloy has a higher number of fine precipitated particles. Compared with Comparative Example 2, the heat-treated CuCrZr alloy has finer precipitated particles. Figure 6(b) shows the transmission electron microscopy microstructure of the heat-treated CuCrZr alloy. The heat-treated CuCrZr alloy has the same cellular subgrain structure and dislocations distributed along the boundaries as those in Comparative Example 1. The ultimate tensile strength of the heat-treated CuCrZr alloy is about 475 MPa, which is much higher than that of the CuCrZr alloys in Comparative Example 1 and Comparative Example 2. The electrical conductivity of the heat-treated alloy was tested, and its electrical conductivity was about 83% IACS, which is much higher than that of the CuCrZr alloy in Comparative Example 1. Therefore, the CuCrZr alloy prepared by this embodiment has a cellular subgrain structure and a higher number of fine precipitated particles, so that the CuCrZr alloy has high strength and high electrical conductivity.

[0056] Example 5

[0057] An embodiment of the present invention provides a method for simultaneously improving the strength and electrical conductivity of an additively manufactured CuCrZr alloy, comprising the following steps:

[0058] Step S1: prepare defect-free high-density CuCrZr alloy using laser powder bed fusion technology, with a laser energy density of about 800 J / mm 3 The defect-free, high-density CuCrZr alloy has no defects such as pores, unmelted powder or cracks, and its density is 99.4%.

[0059] Step S2: placing the defect-free high-density CuCrZr alloy in a muffle furnace at 550° C. and keeping the temperature for 4 hours in a vacuum atmosphere for heat treatment.

[0060] Step S3: After the rated holding time, the heat-treated defect-free high-density CuCrZr alloy is cooled to room temperature to complete the heat treatment at a cooling rate of about 80°C / s to obtain a CuCrZr alloy with high strength and electrical conductivity.

[0061] Figure 7 (a) shows the scanning electron microscopy microstructure of the heat-treated CuCrZr alloy. The grain structure of the heat-treated CuCrZr alloy is the same as that of Comparative Example 1. Compared with Comparative Example 2, the grain size of the heat-treated CuCrZr alloy is finer. Compared with Comparative Example 1, the heat-treated CuCrZr alloy has a higher number of fine precipitated particles. Compared with Comparative Example 2, the heat-treated CuCrZr alloy has finer precipitated particles. Figure 7(b) shows the transmission electron microscopy microstructure of the heat-treated CuCrZr alloy. The heat-treated CuCrZr alloy has the same cellular subgrain structure and dislocations distributed along the boundaries as those in Comparative Example 1. The ultimate tensile strength of the heat-treated CuCrZr alloy is 490 MPa, which is much higher than that of the CuCrZr alloys in Comparative Example 1 and Comparative Example 2. The electrical conductivity of the heat-treated alloy was tested, and its electrical conductivity was approximately 81% IACS, which is much higher than that of the CuCrZr alloy in Comparative Example 1. Therefore, the CuCrZr alloy prepared by this embodiment has a cellular subgrain structure and a higher number of fine precipitated particles, so that the CuCrZr alloy has high strength and high electrical conductivity.

[0062] The present invention has been described in detail above through the embodiments, but the contents described are only exemplary embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. The scope of protection of the present invention is defined by the claims. Any use of the technical solution described in the present invention, or any person skilled in the art who, inspired by the technical solution of the present invention, designs a similar technical solution within the essence and scope of protection of the present invention to achieve the above-mentioned technical effects, or any equivalent changes and improvements made to the scope of application, shall still fall within the scope of protection covered by the patent of the present invention.

Claims

1. A method for simultaneously improving the strength and electrical conductivity of an additively manufactured CuCrZr alloy, characterized in that: The following steps are involved: Step S1, preparing a defect-free high-density CuCrZr alloy using additive manufacturing technology; Step S2, heating the muffle furnace or vacuum heat treatment furnace to 460-700° C., placing the defect-free high-density CuCrZr alloy obtained in step S1 in the furnace, holding the temperature for 0.5-12 hours, and using air, vacuum, or argon as the heat treatment atmosphere; Step S3, after the rated holding time, cooling the defect-free high-density CuCrZr alloy after the heat treatment in step S2 to obtain a CuCrZr alloy with high strength and electrical conductivity, with a cooling rate of 20 to 120°C / s; In step S1, the additive manufacturing technology is laser powder bed fusion technology; In step S1, the process parameters of the laser powder bed fusion technology are as follows: the laser energy density range is 200~1000J / mm 3 , a defect-free high-density CuCrZr alloy block with a density higher than 99.3% was prepared.

2. The method for simultaneously improving the strength and electrical conductivity of an additively manufactured CuCrZr alloy according to claim 1, wherein: In step S2, the time for placing the defect-free high-density CuCrZr alloy into the muffle furnace or vacuum heat treatment furnace is controlled within 1 minute, and the furnace door is closed in time.

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