CN112317755B - Method for improving strength and conductivity of Cu-Cr-Nb alloy - Google Patents

Method for improving strength and conductivity of Cu-Cr-Nb alloy Download PDF

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CN112317755B
CN112317755B CN202010891130.4A CN202010891130A CN112317755B CN 112317755 B CN112317755 B CN 112317755B CN 202010891130 A CN202010891130 A CN 202010891130A CN 112317755 B CN112317755 B CN 112317755B
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strength
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刘祖铭
任亚科
吕学谦
魏冰
周旭
农必重
卢思哲
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Central South University
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Abstract

The invention provides a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy. The method prepares Cu-Cr-Nb alloy powder with high sphericity and less satellite powder by argon atomization, and adopts nitrogen low-temperature air separation to screen powder and reduction atmosphere packaging; SLM forming is carried out in the atmosphere with 1-3% of hydrogen and the balance of argon, so that the oxygen content in the alloy is effectively reduced, and the conductivity of the alloy is improved; and finally, placing the formed piece in a reducing atmosphere for two-stage aging treatment to obtain the Cu-Cr-Nb alloy with high strength, high plasticity and high conductivity. The Cu-Cr-Nb alloy prepared by the method has the room-temperature tensile strength of not less than 623MPa, the elongation of not less than 27 percent, the microhardness of not less than 217HV, the conductivity of 84 percent IACS and the high-temperature tensile strength of not less than 140MPa at 700 ℃. The invention has important application value in the field of high-strength and high-conductivity copper alloy.

Description

Method for improving strength and conductivity of Cu-Cr-Nb alloy
Technical Field
The invention provides a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy, belonging to the field of additive manufacturing and copper alloys.
Background
The strength and the electric conductivity of the copper alloy are mutually restricted, and how to simultaneously improve the strength and the electric conductivity of the copper alloy is a problem which is troubled. The Cu-Cr-Nb alloy has good strength, creep property, high heat conductivity, low cycle fatigue property and high temperature stability, and is an important structural functional material in the fields of aerospace and nuclear energy. In recent years, extensive research has been conducted to further improve the overall performance. Guo et al (Xiaolinguo, et al. Microtreucture and properties of Cu-Cr-Nb alloy with high strength, high electrical conductivity and good electrical resistance property and improved temperature property. materials Science and Engineering: A.2019.749: 281-. Shukla et al (AK Shukla, et al. Effect of powder milling on mechanical properties of hot-pressed and hot-rolled Cu-Cr-Nb alloy. journal of alloys and Compounds,2013,580: 427-. Chinese patent CN107586977A discloses a preparation method of a high-strength high-conductivity copper alloy bar material, which comprises the following steps: placing the Cu-Nb intermediate alloy, the Cr particles and the Cu blocks in a crucible, and smelting in an induction smelting furnace protected by argon to obtain Cu-Cr-Nb alloy liquid; pouring and cooling the Cu-Cr-Nb alloy liquid in a fine-diameter graphite die to obtain a Cu-Cr-Nb alloy bar; and putting the bar into a heat treatment furnace for solid solution and aging heat treatment, and machining to obtain a finished product of the Cu-Cr-Nb alloy bar. The patent does not disclose performance data for the finished product produced. The above researches show that the problem of synchronously improving the conductivity and the strength of the Cu-Cr-Nb alloy is not effectively solved.
Aiming at the problems, the method adopts argon atomization to prepare Cu-Cr-Nb alloy powder with high sphericity and less satellite powder, and performs Selective Laser Melting (SLM) forming in a protective reducing atmosphere containing 3% (volume fraction) of hydrogen, so that the oxygen content of the prepared alloy is effectively reduced, and the conductivity of the alloy is improved; and finally, performing two-stage and gradient aging treatment on the formed piece to obtain the Cu-Cr-Nb alloy with high strength, high plasticity and high conductivity. A large amount of dispersed and fine nucleus-forming particles are formed by first-stage aging; the secondary aging is carried out in a graded manner, the size of a precipitated phase is refined, the solid solution amount of alloy elements in a copper matrix is reduced, and the mechanical property and the electric conductivity of the alloy are synchronously improved.
Disclosure of Invention
Aiming at the problems that the strength and the conductivity of a copper alloy are mutually restricted and the synchronous improvement of the strength and the conductivity is difficult to realize, the invention discloses a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy, which adopts argon atomization to prepare Cu-Cr-Nb alloy powder with high sphericity and less satellite powder, and carries out SLM forming in a protective reducing atmosphere with 1-3% of hydrogen content and more than or equal to 97% of argon content (volume fraction, the same below), thereby effectively reducing the oxygen content of the alloy and improving the conductivity of the alloy; and finally, performing two-stage and gradient aging treatment on the formed piece in a special atmosphere to obtain the Cu-Cr-Nb alloy with high strength, high plasticity and high conductivity. The first-stage aging forms a large amount of finely dispersed nucleation mass points, the second-stage aging is carried out in a gradient manner, the size of a precipitated phase is refined, the solid solution amount of alloy elements in a copper matrix is reduced, and the mechanical property and the electric conductivity of the alloy are synchronously improved. The prepared Cu-Cr-Nb alloy has excellent comprehensive performance, room-temperature tensile strength of not less than 623MPa, microhardness of not less than 217HV, elongation of not less than 27%, conductivity of reaching 84% IACS, 700 ℃ tensile strength of not less than 140MPa, and important application value.
The invention discloses a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy, which is implemented according to the following steps:
(1) preparation of Cu-Cr-Nb alloy powder by argon atomization
Putting the electrolytic pure copper and the Cr-Nb intermediate alloy into an induction melting furnace of a vacuum atomization device for melting; after the metal is completely melted and alloyed, vacuum degassing is carried out for 10-15min at 1560-1600 ℃, and then atomization is carried out by utilizing high-purity argon (the purity is 99.99 wt%); finally, screening out the required Cu-Cr-Nb alloy powder by utilizing nitrogen winnowing screen powder and ultrasonic vibration screening, drying, and packaging in a reducing atmosphere, wherein the alloy powder is 0.5-7.0% by mass of Cr, 0.1-7.0% by mass of Nb and the balance of copper;
(2) laser additive manufacturing pre-preparation
Designing a three-dimensional model of the part by using software according to the shape of the required part, then introducing the three-dimensional model into laser additive manufacturing equipment, and introducing process parameters into a laser additive manufacturing system after the software is subjected to self-slicing treatment;
(3) additive manufacturing by SLM
Firstly, laying Cu-Cr-Nb alloy powder, then carrying out laser selective melting on the laid powder bed according to the slice layer information in the second step, wherein the scanning mode comprises contour scanning and entity scanning, when each layer is scanned, contour scanning is firstly carried out, then entity scanning is carried out, the entity scanning adopts a snake-shaped scanning strategy, and then contour scanning is carried out again; the steps are powder laying and laser melting processes;
repeating the steps until the whole part is printed; then separating the formed part from the substrate to obtain a formed part;
(4) two stage aging heat treatment
Performing two-stage aging treatment on the formed piece in a mixed gas atmosphere with hydrogen content of 1-3% (volume fraction, the same below) and argon content of more than or equal to 97%, wherein the first-stage aging temperature is 150-200 ℃, and the time is 0.5-3 h; and performing secondary aging in a gradient manner, wherein the first gradient temperature is 260-400 ℃, preserving heat for 10-60min, then heating to the second gradient of 450-560 ℃ along with the furnace, and preserving heat for 0.5-3h to obtain the Cu-Cr-Nb alloy with high strength, high plasticity and high conductivity. The invention relates to a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy, wherein an alloy melt prepared by smelting is guided into a tightly coupled gas atomization furnace through a guide pipe at the flow speed of 3.5-4kg/min, the atomization temperature is controlled to be 1600-1900 ℃, the pressure of a powder making furnace is 0.22-0.23bar, the pressure of an atomization medium is 3.5-5.5MPa, the particle size of Cu-Cr-Nb alloy powder obtained by screening powder by air separation is 15-67 mu m, D10 is 15-25 mu m, D50 is 27-33 mu m, and D90 is 40-55 mu m;
the invention relates to a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy, which is implemented in a vacuum atmosphere, wherein the drying temperature of selected metal powder is 80-100 ℃, and the drying time is 1-2 h.
The invention relates to a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy, which comprises the following steps of alloy powder packaging: vacuumizing, filling reducing protective gas with hydrogen content of 1-3% and argon content not less than 97%, and packaging.
The invention discloses a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy, wherein SLM (selective laser melting) profile scanning parameters are as follows: the diameter of a laser spot is 0.08-0.1mm, the laser power is 100-150W, and the scanning speed is 1000-1400 mm/s; the laser power of the entity scanning is 330W-370W, the scanning speed is 550mm/s-950mm/s, the lap joint spacing is 0.06mm-0.16mm, and the energy density is 100J/mm3-300 J/mm3The layers were rotated 67 ° between the shaping layers and the layer thickness was 30 μm.
The invention relates to a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy, wherein in laser material increase manufacturing, mixed gas with the hydrogen content of 1-3 percent and the argon content of more than or equal to 97 percent is introduced into a working cavity of equipment, so that the oxygen content in the working cavity is less than 0.1 percent. The substrate used for printing is a stainless steel substrate or a copper substrate, and the preheating temperature of the substrate is 100-200 ℃ before printing.
The invention relates to a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy, which is characterized in that the Cu-Cr-Nb alloy prepared by SLM has the tensile strength of 375-399MPa, the microhardness of 120-139HV, the elongation of 35-41% and the conductivity of 20-25% IACS at room temperature.
The invention relates to a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy, wherein the first aging cooling mode is water cooling or air cooling; the second aging cooling mode is furnace cooling.
The invention relates to a method for improving the strength and the conductivity of a Cu-Cr-Nb alloy, after the Cu-Cr-Nb alloy prepared by SLM is subjected to heat treatment, the room temperature tensile strength is not lower than 623MPa, the microhardness is not lower than 217HV, the elongation is not lower than 27%, and the conductivity is not lower than 74% IACS; the tensile strength at 700 ℃ is 145-155 MPa.
When the Cr content in Cu-Cr-Nb alloy powder is 0.71wt% and the Nb content is 0.11wt%, the tensile strength of a product obtained after heat treatment is 623MPa, the microhardness is 217HV, the elongation is 27% and the conductivity is 84% IACS.
When the Cr content in Cu-Cr-Nb alloy powder is 1.58wt% and the Nb content is 1.36wt%, the tensile strength of a product obtained after heat treatment is 635MPa, the microhardness is 221HV, the elongation is 28%, and the conductivity is 81% IACS.
The invention has the advantages and positive effects that:
1. the invention utilizes argon gas atomization powder preparation, and the powder supersaturated solid solution with uniform components is obtained by rapid solidification, thereby effectively improving the solid solution amount of alloying elements Cr and Nb in a copper matrix, inhibiting the formation of coarse second phases and the growth of crystal grains in the solidification process of an alloy melt, and creating conditions for obtaining fine second phases for subsequent forming and heat treatment, regulating and controlling the microstructure and improving the strength.
2. The powder prepared by the invention is packaged in a reducing atmosphere with the hydrogen content of 1-3 percent and the argon content of more than or equal to 97 percent, and a certain amount of hydrogen atoms are adsorbed on the surface of the powder. In the SLM process, high-temperature dehydrogenation is realized through high-energy laser scanning, a large number of atomic sites are left, the surface activity of a cladding layer is increased, the in-situ enhancement of the bonding force between SLM forming layers is facilitated, the mechanical property of the alloy is improved, the density of a prepared alloy forming part exceeds 99.4%, the tensile strength at room temperature is 370-399MPa, and the elongation is 35-41%.
3. According to the invention, the Cu-Cr-Nb alloy is prepared by SLM, the segregation of alloy components is reduced by extremely fast cooling rate, the solid solution amount of alloy elements in a copper matrix is obviously improved, and conditions are created for regulating and controlling the microstructure and improving the comprehensive performance of the alloy by heat treatment; the rapid solidification and rapid cooling refine grains, thereby improving the strength and the plasticity.
4. According to the invention, SLM forming is carried out in a reducing atmosphere with hydrogen content of 1-3% and argon content of more than or equal to 97%, so that the oxygen content of a formed piece is greatly reduced, and the conductivity of the alloy is effectively improved;
5. the invention carries out two-stage aging in reducing atmosphere, and adopts gradient heat treatment in the two-stage aging, thereby prolonging the aging peak value platform time. Forming a large number of finely dispersed nucleation particles in the alloy through first-stage low-temperature aging, and refining the size of a precipitated phase; the secondary high-temperature aging is carried out in a gradient manner, the aging is fully carried out at the low-temperature stage, the growth of precipitated phases is prevented, the solid solution amount of alloy elements in a copper matrix is reduced, solid solution atoms are fully precipitated by the aging at the high-temperature stage, the mechanical property is improved, and the conductivity is improved; the two-stage aging is carried out in the reducing atmosphere containing hydrogen, so that the oxygen content in the alloy is effectively reduced, and the conductivity of the alloy is finally improved.
6. The alloy obtained by the invention has fine crystal grains and uniform components, the aging precipitation phase is a nano phase and is dispersed and distributed in an alloy matrix, and the size of the nano phase is mainly 30-40nm and less than 4 nm.
7. According to the invention, for the copper alloy with lower copper content (93.9%), the tensile strength and the electric conductivity of the product can be simultaneously improved through the optimization of the parameters of the 3D printing and heat treatment processes.
8. The invention forms a large amount of dispersed and distributed tiny nucleation mass points by primary aging, and carries out secondary aging by gradient, thereby refining the size of a precipitated phase, reducing the solid solution amount of alloy elements and synchronously improving the mechanical property and the electric conductivity of the alloy. The prepared Cu-Cr-Nb alloy has excellent comprehensive performance, the room-temperature tensile strength is not lower than 623MPa, the microhardness is not lower than 217HV, the elongation is not lower than 27%, the conductivity reaches 84% IACS, and the 700-DEG C tensile strength is not lower than 140 MPa.
Drawings
FIG. 1 is a metallographic micrograph of the microstructure of a Cu-Cr-Nb alloy prepared by SLM according to an example.
FIG. 2 is an SEM photograph of the microstructure of an example SLM-fabricated Cu-Cr-Nb alloy.
FIG. 3 is a TEM micrograph of the microstructure of a Cu-Cr-Nb alloy prepared by an SLM of an example.
FIG. 4 is an SEM image of the microstructure of a Cu-Cr-Nb alloy dual stage aging sample prepared by an SLM of an example.
Detailed Description
The invention is further illustrated with reference to the following figures and specific examples.
The first embodiment is as follows:
(1) preparation of copper alloy powder suitable for SLM
Putting the raw materials of the electrolytic pure copper and the Cr-Nb intermediate alloy into a vacuum induction smelting furnace for smelting; after the raw materials are melted and completely alloyed, vacuum degassing is carried out for 10min at 1580 ℃, then the completely alloyed melt is led into a close-coupled gas atomization furnace through a guide pipe at the flow rate of 3.5kg/min, the atomization temperature is controlled to be 1600 ℃, the pressure of an atomization medium is controlled to be 3.5MPa, high-purity argon (the purity is 99.99 wt%) is used as an atomization medium to smash metal liquid into fine liquid drops, and Cu-Cr-Nb alloy powder is formed after cooling and rapid solidification; and finally, screening out the required Cu-Cr-Nb alloy powder by using a nitrogen screening device and ultrasonic vibration screening at a low temperature, drying for 1h at a vacuum temperature of 100 ℃, packaging in a reducing atmosphere with a hydrogen content of 3 v% and an argon content of 97 v%, wherein the Cr content of the alloy powder is 1.58wt%, the Nb content is 1.36wt%, and the balance is copper.
(2) SLM forming Cu-Cr-Nb alloy
A three-dimensional cylinder model with the diameter of 30mm and the height of 53mm is constructed by using design software, the three-dimensional cylinder model is converted into an STL file and then is introduced into laser additive manufacturing equipment, and process parameters are introduced into a laser additive manufacturing system after the software is subjected to self-slicing processing. Heating the substrate to 150 ℃, then filling Cu-Cr-Nb alloy powder into a powder supply cylinder, spreading powder, and introducing mixed gas with the hydrogen content of 3 v% and the argon content of 97 v% into the working cavity until the oxygen content is lower than 0.1%. And then, entering a printing program, and continuously repeating the steps of powder paving and laser powder scanning until the printing is finished to obtain the cylinder.
Wherein the grain diameter of the Cu-Cr-Nb alloy powder is 15-67 μm, the D10 is 17.3 μm, the D50 is 28.2 μm, and the D90 is 45.9 μm.
The SLM profile scan parameters are: the diameter of a laser spot is 0.1mm, the laser power is 130W, and the scanning speed is 1200 mm/s.
The SLM was physically scanned at a laser power of 330W, a scan rate of 825mm/s, a lap spacing of 0.08 mm, a laser spot diameter of 0.12mm, a 67 deg. rotation between the shaping layers, and a layer thickness of 30 μm.
The density of the formed part reaches 8.85g/cm through the Archimedes drainage method3The relative density was 99.6%, the tensile strength was 395MPa at room temperature, the microhardness was 135HV, the electrical conductivity was 23% IACS, and the elongation was 37%. FIG. 1 is a metallographic photograph of a microstructure of an SLM-formed Cu-Cr-Nb alloy, FIG. 2 is an SEM photograph of a microstructure of an SLM-formed Cu-Cr-Nb alloy, and FIG. 3 is a TEM photograph of a microstructure of an SLM-formed Cu-Cr-Nb alloy. The result shows that the alloy has fewer internal defects and only a few pores, the alloy structure is fine through SLM forming, a large number of nanoscale second phases are uniformly distributed in grain boundaries and crystal grains, and the size of the second phases is greatly reduced compared with that of the Cu-Cr-Nb alloy (0.7-7 mu m) prepared by the traditional casting method.
(3) Two stage aging treatment
And (2) carrying out two-stage aging treatment on the formed piece in a mixed gas atmosphere with the hydrogen content of 3 v% and the argon content of 97 v%, wherein the first-stage aging temperature is 180 ℃, the time is 1h, water cooling is carried out, the first gradient temperature of the second-stage aging is 360 ℃, the temperature is kept for 15min, the temperature is increased to the second gradient 530 ℃ along with the furnace, the temperature is kept for 1.5h, and the Cu-Cr-Nb alloy with high strength, high plasticity and high conductivity is obtained after cooling along with the furnace. At room temperature, the tensile strength is 635MPa, the microhardness is 221HV, the conductivity is 81% IACS, and the elongation is 28%. FIG. 4 is an SEM image of the microstructure of the alloy after the two-stage aging treatment, showing a significant increase in the number of second phases after the aging treatment.
Example two: examples of lower copper content
(1) Preparation of copper alloy powder suitable for SLM
Putting the electrolytic pure copper and the Cr-Nb intermediate alloy into a vacuum induction smelting furnace for smelting; after the raw materials are melted and completely alloyed, vacuum degassing is carried out for 10min at 1580 ℃, then the completely alloyed melt is led into a close-coupled gas atomization furnace through a guide pipe at the flow rate of 3.5kg/min, the atomization temperature is controlled to be 1600 ℃, the pressure of an atomization medium is controlled to be 3.5MPa, high-purity argon (the purity is 99.99 wt%) is used as an atomization medium to smash metal liquid into fine liquid drops, and Cu-Cr-Nb alloy powder is formed after cooling and rapid solidification; and finally, screening out the required Cu-Cr-Nb alloy powder by using a nitrogen screening device and ultrasonic vibration screening at a low temperature, drying for 1.5h at 100 ℃ in vacuum, and packaging in a reducing atmosphere with the hydrogen content of 2 v% and the argon content of 98 v%, wherein the alloy powder is 3.2% by mass of Cr, 2.9% by mass of Nb and the balance of copper.
(2) SLM forming Cu-Cr-Nb alloy
A three-dimensional cylinder model with the diameter of 30mm and the height of 53mm is constructed by using design software, the three-dimensional cylinder model is converted into an STL file and then is introduced into laser additive manufacturing equipment, and process parameters are introduced into a laser additive manufacturing system after the software is subjected to self-slicing processing. Heating the substrate to 150 ℃, adding Cu-Cr-Nb alloy powder into a powder supply cylinder, spreading the powder, and introducing mixed gas with the hydrogen content of 2 v% and the argon content of 98 v% into the working cavity until the oxygen content is lower than 0.1%. And then, entering a printing program, and continuously repeating the steps of powder paving and laser powder scanning until the printing is finished to obtain the cylinder.
Wherein the grain diameter of the Cu-Cr-Nb alloy powder is 15-67 μm, the D10 is 17.3 μm, the D50 is 28.2 μm, and the D90 is 45.9 μm.
The SLM profile scan parameters are: the diameter of a laser spot is 0.1mm, the laser power is 150W, and the scanning speed is 1200 mm/s.
The SLM has the physical scanning laser power of 350W, the scanning speed of 700mm/s, the lapping interval of 0.10mm, the laser spot diameter of 0.12mm, the rotation between the forming layers of 67 degrees and the layer thickness of 30 μm.
The density of the product reaches 8.81g/cm by the Archimedes drainage method3The relative density was 99.1%. At room temperature, the tensile strength is 397MPa, the microhardness is 139HV, the conductivity is 20% IACS, and the elongation is 36%.
(3) Two stage aging treatment
And (2) carrying out two-stage aging treatment on the formed piece in a mixed atmosphere with the hydrogen content of 2 v% and the argon content of 98 v%, wherein the first-stage aging temperature is 160 ℃, the time is 1h, water cooling is carried out, the first gradient temperature of the second-stage aging is 300 ℃, the temperature is kept for 20min, the temperature is increased to the second gradient 560 ℃ along with the furnace, the temperature is kept for 1h, and the temperature is cooled along with the furnace, so that the Cu-Cr-Nb alloy with high strength, high plasticity and high conductivity is obtained. At room temperature, the tensile strength reaches 657MPa, the microhardness is 228HV, the conductivity is improved to 74.3 percent IACS, and the elongation is 27 percent.
Example three: examples of higher copper content
(1) Preparation of copper alloy powder suitable for SLM
Putting the electrolytic pure copper and the Cr-Nb intermediate alloy into a vacuum induction melting furnace for alloy melting; after the alloy is completely melted, vacuum degassing is carried out for 10min at 1580 ℃, then the completely melted alloy is led into a close-coupled gas atomization furnace through a guide pipe at the flow rate of 3.5kg/min, the atomization temperature is controlled to be 1600 ℃, the pressure of an atomization medium is controlled to be 3.5MPa, high-purity argon (the purity is 99.99 wt%) is used as the atomization medium, the metal liquid flow is smashed into fine liquid drops, and Cu-Cr-Nb alloy powder is formed after cooling and rapid solidification; and finally, screening out the required Cu-Cr-Nb alloy powder by using a nitrogen screening device and ultrasonic vibration screening at low temperature, drying for 1h at 100 ℃ in vacuum, and packaging in a reducing atmosphere with the hydrogen content of 3 v% and the argon content of 97 v%, wherein the alloy powder contains 0.71 mass percent of Cr, 0.11 mass percent of Nb and the balance of copper.
(2) SLM forming Cu-Cr-Nb alloy
A three-dimensional cylinder model with the diameter of 30mm and the height of 53mm is constructed by using design software, the three-dimensional cylinder model is converted into an STL file and then is introduced into laser additive manufacturing equipment, and process parameters are introduced into a laser additive manufacturing system after the software is subjected to self-slicing processing. Heating the substrate to 150 ℃, adding Cu-Cr-Nb alloy powder into a powder supply cylinder, spreading the powder, and introducing mixed gas with the hydrogen content of 3 v% and the argon content of 97 v% into the working cavity until the oxygen content is lower than 0.1%. And then, entering a printing program, and continuously repeating the steps of powder paving and laser powder scanning until the printing is finished to obtain the cylinder.
Wherein the grain diameter of the Cu-Cr-Nb alloy powder is 15-67 μm, the D10 is 17.3 μm, the D50 is 28.2 μm, and the D90 is 45.9 μm.
The SLM profile scan parameters are: the diameter of a laser spot is 0.1mm, the laser power is 150W, and the scanning speed is 1200 mm/s.
The SLM physically scans with laser power of 350W, scanning speed of 725mm/s, lapping interval of 0.10mm, laser spot diameter of 0.12mm, rotation between shaping layers of 67 degrees, and layer thickness of 30 μm.
The density of the product reaches 8.81g/cm by the Archimedes drainage method3The relative density was 99.3%. At room temperature, the tensile strength was 377MPa, the microhardness was 121HV, the electrical conductivity was 25% IACS, and the elongation was 37%.
(3) Two stage aging treatment
And (2) carrying out two-stage aging treatment on the formed piece in a mixed atmosphere with the hydrogen content of 3 v% and the argon content of 97 v%, wherein the first-stage aging temperature is 150 ℃, the time is 1h, water cooling is carried out, the first gradient temperature of the second-stage aging is 300 ℃, the temperature is kept for 20min, the temperature is increased to the second gradient 470 ℃ along with the furnace, the temperature is kept for 1h, and the Cu-Cr-Nb alloy with high strength, high plasticity and high conductivity is obtained after cooling along with the furnace. At room temperature, the tensile strength reaches 623MPa, the microhardness is 217HV, the electric conductivity is improved to 84% IACS, and the elongation is 27%.
Comparative example one: only argon is introduced during printing
(1) Preparation of copper alloy powder suitable for SLM
Putting the raw materials of the electrolytic pure copper and the Cr-Nb intermediate alloy into a vacuum induction melting furnace for melting; after the raw materials are melted and completely alloyed, vacuum degassing is carried out for 10min at 1580 ℃, then the completely alloyed melt is led into a close-coupled gas atomization furnace through a guide pipe at the flow rate of 3.5kg/min, the atomization temperature is controlled to be 1600 ℃, the pressure of an atomization medium is controlled to be 3.5MPa, high-purity argon (the purity is 99.99 wt%) is used as an atomization medium to smash metal liquid into fine liquid drops, and Cu-Cr-Nb alloy powder is formed after cooling and rapid solidification; and finally, screening the required Cu-Cr-Nb alloy powder by using a nitrogen screening device and ultrasonic vibration screening at a low temperature, drying for 1h at the vacuum temperature of 100 ℃, packaging in a reducing atmosphere with the hydrogen content of 3 v% and the argon content of 97 v%, wherein the Cr content of the alloy powder is 1.58wt%, the Nb content is 1.36% by mass, and the balance is copper.
(2) SLM forming Cu-Cr-Nb alloy
A three-dimensional cylinder model with the diameter of 30mm and the height of 53mm is constructed by using design software, the three-dimensional cylinder model is converted into an STL file and then is introduced into laser additive manufacturing equipment, and process parameters are introduced into a laser additive manufacturing system after the software is subjected to self-slicing processing. And heating the substrate to 150 ℃, adding Cu-Cr-Nb alloy powder into the powder supply cylinder, spreading the powder, and introducing argon into the working cavity until the oxygen content is lower than 0.1%. And then, entering a printing program, and continuously repeating the steps of powder paving and laser powder scanning until printing is finished to obtain the cylinder.
Wherein the grain diameter of the Cu-Cr-Nb alloy powder is 15-67 μm, the D10 is 17.3 μm, the D50 is 28.2 μm, and the D90 is 45.9 μm.
The SLM profile scan parameters are: the diameter of a laser spot is 0.1mm, the laser power is 150W, and the scanning speed is 1200 mm/s.
The SLM was physically scanned at a laser power of 330W, a scan rate of 825mm/s, a lap gap of 0.10mm, a laser spot diameter of 0.12mm, a 67 deg. rotation between the shaping layers, and a layer thickness of 30 μm.
The density of the resin reaches 8.81g/cm3 through an Archimedes drainage method, and the relative density is 99.1%. At room temperature, the tensile strength is 370MPa, the microhardness is 121HV, the conductivity is 17% IACS, and the elongation is 38%.
(3) Two stage aging treatment
And (3) carrying out two-stage aging treatment on the formed piece in a mixed atmosphere with the hydrogen content of 3 v% and the argon content of 97 v%, wherein the first-stage aging temperature is 180 ℃, the time is 1h, the formed piece is cooled by water, the first gradient temperature of the second-stage aging is 360 ℃, the temperature is kept for 15min, the formed piece is heated to the second gradient temperature of 530 ℃ along with the furnace, the temperature is kept for 1.5h, and the formed piece is cooled along with the furnace. At room temperature, the tensile strength is 597MPa, the microhardness is 190HV, the conductivity is 75% IACS, and the elongation is 28%.
Comparative example two: single stage ageing treatment
(1) Preparation of copper alloy powder suitable for SLM
Putting the raw materials of the electrolytic pure copper and the Cr-Nb intermediate alloy into a vacuum induction smelting furnace for smelting; after the raw materials are melted and completely alloyed, vacuum degassing is carried out for 10min at 1580 ℃, then the completely alloyed melt is led into a close-coupled gas atomization furnace through a guide pipe at the flow rate of 3.5kg/min, the atomization temperature is controlled to be 1600 ℃, the pressure of an atomization medium is controlled to be 3.5MPa, high-purity argon (the purity is 99.99 wt%) is used as an atomization medium to smash metal liquid into fine liquid drops, and Cu-Cr-Nb alloy powder is formed after cooling and rapid solidification; and finally, screening out the required Cu-Cr-Nb alloy powder by using a nitrogen screening device and ultrasonic vibration screening at a low temperature, drying for 1h at a vacuum temperature of 100 ℃, packaging in a reducing atmosphere with a hydrogen content of 3 v% and an argon content of 97 v%, wherein the Cr content of the alloy powder is 1.58wt%, the Nb content is 1.36wt%, and the balance is copper.
(2) SLM forming Cu-Cr-Nb alloy
A three-dimensional cylinder model with the diameter of 30mm and the height of 53mm is constructed by using design software, the three-dimensional cylinder model is converted into an STL file and then is introduced into laser additive manufacturing equipment, and process parameters are introduced into a laser additive manufacturing system after the software is subjected to self-slicing processing. Heating the substrate to 150 ℃, adding Cu-Cr-Nb alloy powder into a powder supply cylinder, spreading the powder, and introducing a mixed atmosphere with the hydrogen content of 3 v% and the argon content of 97 v% into the working cavity until the oxygen content is lower than 0.1%. And then, entering a printing program, and continuously repeating the steps of powder paving and laser powder scanning until the printing is finished to obtain the cylinder.
Wherein the grain diameter of the Cu-Cr-Nb alloy powder is 15-67 μm, the D10 is 17.3 μm, the D50 is 28.2 μm, and the D90 is 45.9 μm.
The SLM profile scan parameters are: the diameter of a laser spot is 0.1mm, the laser power is 130W, and the scanning speed is 1200 mm/s.
The SLM was physically scanned at a laser power of 330W, a scan rate of 825mm/s, a lap spacing of 0.08 mm, a laser spot diameter of 0.12mm, a 67 deg. rotation between the shaping layers, and a layer thickness of 30 μm.
The density of the resin reaches 8.81g/cm3 through an Archimedes drainage method, and the relative density is 99.1%. At room temperature, the tensile strength is 395MPa, the microhardness is 135HV, the conductivity is 23% IACS, and the elongation is 37%.
(3) Single stage ageing treatment
And carrying out single-stage aging treatment on the formed piece in a mixed atmosphere with the hydrogen content of 3 v% and the argon content of 97 v%, wherein the aging temperature is 530 ℃ and the time is 1.5 h. At room temperature, the tensile strength was 589MPa, the microhardness was 189HV, the electrical conductivity was 75.5% IACS, and the elongation was 26%.
Comparative example three: (Secondary aging indifferent gradient)
(1) Preparation of copper alloy powder suitable for SLM
Putting the raw materials of the electrolytic pure copper and the Cr-Nb intermediate alloy into a vacuum induction smelting furnace for smelting; after the raw materials are melted and completely alloyed, vacuum degassing is carried out for 10min at 1580 ℃, then the completely alloyed melt is led into a close-coupled gas atomization furnace through a guide pipe at the flow rate of 3.5kg/min, the atomization temperature is controlled to be 1600 ℃, the pressure of an atomization medium is 3.5MPa, high-purity argon (the purity is 99.99 wt%) is used as an atomization medium to smash metal liquid flow into fine liquid drops, and Cu-Cr-Nb alloy powder is formed after cooling and rapid solidification; finally, screening out the required Cu-Cr-Nb alloy powder at low temperature by using a nitrogen screening device and ultrasonic vibration screening, drying for 1h at the vacuum temperature of 100 ℃, packaging in a reducing atmosphere with the hydrogen content of 3 v% and the argon content of 97 v%, wherein the Cr content of the alloy powder is 1.58wt%, the Nb content is 1.36% by mass, and the balance is copper.
(2) SLM forming Cu-Cr-Nb alloy
A three-dimensional cylinder model with the diameter of 30mm and the height of 53mm is constructed by using design software, the three-dimensional cylinder model is converted into an STL file and then is introduced into laser additive manufacturing equipment, and process parameters are introduced into a laser additive manufacturing system after the software is subjected to self-slicing processing. Heating the substrate to 150 ℃, adding Cu-Cr-Nb alloy powder into a powder supply cylinder, spreading the powder, and introducing a mixed atmosphere with the hydrogen content of 3 v% and the argon content of 97 v% into the working cavity until the oxygen content is lower than 0.1%. And then, entering a printing program, and continuously repeating the steps of powder paving and laser powder scanning until the printing is finished to obtain the cylinder.
Wherein the grain diameter of the Cu-Cr-Nb alloy powder is 15-67 μm, the D10 is 17.3 μm, the D50 is 28.2 μm, and the D90 is 45.9 μm.
The SLM profile scan parameters are: the diameter of a laser spot is 0.1mm, the laser power is 130W, and the scanning speed is 1200 mm/s.
The SLM was physically scanned at a laser power of 330W, a scan rate of 825mm/s, a lap spacing of 0.08 mm, a laser spot diameter of 0.12mm, a 67 deg. rotation between the shaping layers, and a layer thickness of 30 μm.
The density of the resin reaches 8.81g/cm3 through an Archimedes drainage method, and the relative density is 99.1%. At room temperature, the tensile strength is 395MPa, the microhardness is 135HV, the conductivity is 23% IACS, and the elongation is 37%.
(3) Two stage aging treatment
And placing the formed piece in a mixed atmosphere with 3 v% of hydrogen and 97 v% of argon to perform two-stage aging treatment, wherein the first-stage aging temperature is 180 ℃, the time is 1h, the water cooling is performed, the second-stage aging temperature is 530 ℃, the heat preservation is performed for 2h, and the formed piece is cooled along with a furnace. At room temperature, the tensile strength is 607MPa, the microhardness is 205HV, the electric conductivity is 77 percent IACS, and the elongation is 28 percent.
Comparative example four: (melt flow velocity and atomizing medium gas pressure are too low)
(1) Preparation of SLM copper alloy powder
Putting the electrolytic pure copper and the Cr-Nb intermediate alloy into a vacuum induction smelting furnace for smelting; after the raw materials are melted and completely alloyed, vacuum degassing is carried out for 10min at 1580 ℃, then the completely alloyed melt is led into a close-coupled gas atomization furnace through a guide pipe at the flow rate of 3.2kg/min, the atomization temperature is controlled to be 1600 ℃, the pressure of an atomization medium is controlled to be 3MPa, high-purity argon (the purity is 99.99 wt%) is used as an atomization medium to smash metal liquid flow into fine liquid drops, and Cu-Cr-Nb alloy powder is formed after cooling and rapid solidification; finally, screening out the required Cu-Cr-Nb alloy powder by using a nitrogen screening device at low temperature, drying for 1h at 100 ℃ in vacuum, packaging in a reducing atmosphere with the hydrogen content of 3 v% and the argon content of 97 v%, wherein the alloy powder comprises 1.49% by mass of Cr, 1.33% by mass of Nb and the balance of copper.
(2) SLM forming Cu-Cr-Nb alloy
A three-dimensional cylinder model with the diameter of 30mm and the height of 53mm is constructed by using design software, the three-dimensional cylinder model is converted into an STL file and then is introduced into laser additive manufacturing equipment, and process parameters are introduced into a laser additive manufacturing system after the software is subjected to self-slicing processing. Heating the substrate to 150 ℃, adding Cu-Cr-Nb alloy powder into a powder supply cylinder, spreading the powder, and introducing a mixed atmosphere with the hydrogen content of 3 v% and the argon content of 97 v% into the working cavity until the oxygen content is lower than 0.1%. And then, entering a printing program, and continuously repeating the steps of powder paving and laser powder scanning until the printing is finished to obtain the cylinder.
Wherein, the grain diameter of the Cu-Cr-Nb alloy powder is 8-71 μm, the D10 is 17.3 μm, the D50 is 21.3 μm, and the D90 is 41.6 μm, the satellite powder is more, and the sphericity is poor.
The SLM profile scan parameters are: the diameter of a laser spot is 0.1mm, the laser power is 130W, and the scanning speed is 1200 mm/s.
The SLM was physically scanned at a laser power of 330W, a scan rate of 825mm/s, a lap spacing of 0.08 mm, a laser spot diameter of 0.12mm, a 67 deg. rotation between the shaping layers, and a layer thickness of 30 μm.
The density of the shaped parts was 8.76g/cm as measured by the Archimedes drainage method3The relative density was 98.2%, the tensile strength was 347MPa, the microhardness was 113HV, the conductivity was 17% IACS, and the elongation was 38% at room temperature.
(3) Two stage aging treatment
And (3) carrying out two-stage aging treatment on the formed piece in a mixed atmosphere with the hydrogen content of 3 v% and the argon content of 97 v%, wherein the first-stage aging temperature is 180 ℃, the time is 1h, the formed piece is cooled by water, the first gradient temperature of the second-stage aging is 360 ℃, the temperature is kept for 15min, the formed piece is heated to the second gradient temperature of 530 ℃ along with the furnace, the temperature is kept for 1.5h, and the formed piece is cooled along with the furnace. The tensile strength was 605MPa, the microhardness was 202HV, the conductivity was 77% IACS, and the elongation was 28% at room temperature.
Comparative example five: (laser power too small, scanning rate too large)
(1) Preparation of copper alloy powder suitable for SLM
Putting the raw materials of the electrolytic pure copper and the Cr-Nb intermediate alloy into a vacuum induction smelting furnace for smelting; after the raw materials are melted and completely alloyed, vacuum degassing is carried out for 10min at 1580 ℃, then the completely alloyed melt is led into a close-coupled gas atomization furnace through a guide pipe at the flow rate of 3.5kg/min, the atomization temperature is controlled to be 1600 ℃, the pressure of an atomization medium is 3.5MPa, high-purity argon (the purity is 99.99 wt%) is used as an atomization medium to smash metal liquid flow into fine liquid drops, and Cu-Cr-Nb alloy powder is formed after cooling and rapid solidification; finally, screening out the required Cu-Cr-Nb alloy powder at low temperature by using a nitrogen screening device and ultrasonic vibration screening, drying for 1h at the vacuum temperature of 100 ℃, packaging in a reducing atmosphere with the hydrogen content of 3 v% and the argon content of 97 v%, wherein the Cr content of the alloy powder is 1.58wt%, the Nb content is 1.36% by mass, and the balance is copper.
(2) SLM forming Cu-Cr-Nb alloy
A three-dimensional cylinder model with the diameter of 30mm and the height of 53mm is constructed by using design software, the three-dimensional cylinder model is converted into an STL file and then is introduced into laser additive manufacturing equipment, and process parameters are introduced into a laser additive manufacturing system after the software is subjected to self-slicing processing. Heating the substrate to 150 ℃, adding Cu-Cr-Nb alloy powder into a powder supply cylinder, spreading the powder, and introducing a mixed atmosphere with the hydrogen content of 3 v% and the argon content of 97 v% into the working cavity until the oxygen content is lower than 0.1%. And then, entering a printing program, and continuously repeating the steps of powder paving and laser powder scanning until the printing is finished to obtain the cylinder.
Wherein the grain diameter of the Cu-Cr-Nb alloy powder is 15-67 μm, the D10 is 17.3 μm, the D50 is 28.2 μm, and the D90 is 45.9 μm.
The SLM profile scan parameters are: the diameter of a laser spot is 0.1mm, the laser power is 150W, and the scanning speed is 1200 mm/s.
The SLM scanned physically with a laser power of 310W, a scan rate of 1100mm/s, a lap pitch of 0.10mm, a laser spot diameter of 0.12mm, a 67 ° rotation between the shaping layers, and a layer thickness of 30 μm.
The density of the product reaches 8.78g/cm by the Archimedes drainage method3The relative density was 98.7%. At room temperature, the tensile strength is 345MPa, the microhardness is 110HV, the conductivity is 18% IACS, and the elongation is 32%.
(3) Two stage aging treatment
And (3) carrying out two-stage aging treatment on the formed piece in a mixed atmosphere with the hydrogen content of 3 v% and the argon content of 97 v%, wherein the first-stage aging temperature is 180 ℃, the time is 1h, the formed piece is cooled by water, the first gradient temperature of the second-stage aging is 360 ℃, the temperature is kept for 15min, the formed piece is heated to the second gradient temperature of 530 ℃ along with the furnace, the temperature is kept for 1.5h, and the formed piece is cooled along with the furnace. At room temperature, the tensile strength is 598MPa, the microhardness is 199HV, the conductivity is 77% IACS, and the elongation is 28%.
Comparative example six: reducing atmosphere packaging treatment is not carried out, only argon is used during 3D printing, and argon atmosphere single-stage aging is carried out during heat treatment
(1) Preparation of copper alloy powder suitable for SLM
Putting the raw materials of the electrolytic pure copper and the Cr-Nb intermediate alloy into a vacuum induction smelting furnace for smelting; after the raw materials are melted and completely alloyed, vacuum degassing is carried out for 10min at 1580 ℃, then the completely alloyed melt is led into a close-coupled gas atomization furnace through a guide pipe at the flow rate of 3.5kg/min, the atomization temperature is controlled to be 1600 ℃, the pressure of an atomization medium is controlled to be 3.5MPa, high-purity argon (the purity is 99.99 wt%) is used as an atomization medium to smash metal liquid into fine liquid drops, and Cu-Cr-Nb alloy powder is formed after cooling and rapid solidification; and finally, screening out the required Cu-Cr-Nb alloy powder by using a nitrogen screening device and ultrasonic vibration screening at a low temperature, drying for 1h at a vacuum temperature of 100 ℃, packaging in a reducing atmosphere with a hydrogen content of 3 v% and an argon content of 97 v%, wherein the Cr content of the alloy powder is 1.58wt%, the Nb content is 1.36wt%, and the balance is copper.
(2) SLM forming Cu-Cr-Nb alloy
A three-dimensional cylinder model with the diameter of 30mm and the height of 53mm is constructed by using design software, the three-dimensional cylinder model is converted into an STL file and then is introduced into laser additive manufacturing equipment, and process parameters are introduced into a laser additive manufacturing system after the software is subjected to self-slicing processing. And heating the substrate to 150 ℃, adding Cu-Cr-Nb alloy powder into the powder supply cylinder, spreading the powder, and introducing argon into the working cavity until the oxygen content is lower than 0.1%. And then, entering a printing program, and continuously repeating the steps of powder paving and laser powder scanning until printing is finished to obtain the cylinder.
Wherein the grain diameter of the Cu-Cr-Nb alloy powder is 15-67 μm, the D10 is 17.3 μm, the D50 is 28.2 μm, and the D90 is 45.9 μm.
The SLM profile scan parameters are: the diameter of a laser spot is 0.1mm, the laser power is 150W, and the scanning speed is 1200 mm/s.
The SLM was physically scanned at a laser power of 330W, a scan rate of 825mm/, a lap spacing of 0.10mm, a laser spot diameter of 0.12mm, a 67 deg. rotation between the shaping layers, and a layer thickness of 30 μm.
The density of the product reaches 8.81g/cm by the Archimedes drainage method3The relative density was 99.1%. The tensile strength was 359MPa, the microhardness was 118HV, the conductivity was 17% IACS, and the elongation was 38% at room temperature.
(3) Single stage ageing treatment
And carrying out single-stage aging treatment on the formed piece in an argon atmosphere, wherein the aging temperature is 530 ℃, the time is 1.5h, and cooling along with the furnace. At room temperature, the tensile strength is 575MPa, the microhardness is 180HV, the conductivity is 73% IACS, and the elongation is 28%.
It can be seen from the examples and comparative examples that the invention, through the synergistic effect of the various condition parameters and processes, only leads to products with superior properties, which are far lower than the invention when one or several of the implementation steps or implementation condition parameters are outside the scope of the invention as claimed.

Claims (8)

1. A method for improving the strength and the conductivity of a Cu-Cr-Nb alloy is characterized by comprising the following steps:
(1) preparation of Cu-Cr-Nb alloy powder by argon atomization
Putting the electrolytic pure copper and the Cr-Nb intermediate alloy into an induction melting furnace of a vacuum atomization device for alloy melting; after the metal is completely melted, vacuum degassing is carried out for 10-15min at 1560-1600 ℃, and then atomization is carried out in an atomization furnace by using high-purity argon; finally, screening the required Cu-Cr-Nb alloy powder by utilizing nitrogen low-temperature winnowing screening powder and ultrasonic vibration screening, drying, and packaging in a reducing atmosphere, wherein the mass percent of Cr in the alloy powder is 0.5-7%, the mass percent of Nb is 0.1-7%, and the balance is copper;
(2) laser additive manufacturing pre-preparation
Designing a three-dimensional model of the part by using design software according to the shape of the required part, then introducing the three-dimensional model into laser additive manufacturing equipment, and introducing process parameters into a laser additive manufacturing system after the software is subjected to self-slicing treatment;
(3) additive manufacturing by SLM
Firstly, laying Cu-Cr-Nb alloy powder, then carrying out laser selective melting on the laid powder bed according to the slice layer information in the second step, wherein the scanning mode comprises contour scanning and entity scanning, when each layer is scanned, contour scanning is firstly carried out, then entity scanning is carried out, the entity scanning adopts a snake-shaped scanning strategy, and then contour scanning is carried out again; the steps are powder laying and laser melting processes;
repeating the steps until the whole part is printed, and then separating the formed part from the substrate to obtain a formed part;
the profile scanning parameters are as follows: the diameter of a laser spot is 0.08-0.1mm, the laser power is 100-150W, and the scanning speed is 1000-1400 mm/s; the laser power of the entity scanning is 330W-370W, the scanning speed is 550mm/s-950mm/s, the lap joint spacing is 0.06mm-0.16mm, and the energy density is 100J/mm3-300J/mm3Rotating the forming layers by 67 degrees, wherein the layer thickness is 30 mu m;
in the step (3), mixed gas with the hydrogen content of 1-3% and the argon content of more than or equal to 97% is introduced into a working cavity of the equipment in the laser additive manufacturing process, so that the oxygen content in the working cavity is less than 0.1%; the substrate used for printing is a stainless steel substrate or a copper substrate, and the preheating temperature of the substrate is 100-200 ℃ before printing;
(4) two stage aging heat treatment
And performing two-stage aging treatment on the formed piece in a mixed gas atmosphere with the hydrogen content of 1-3% and the argon content of more than or equal to 97%, wherein the first-stage aging temperature is 150-200 ℃, the time is 0.5-3h, the second-stage aging is performed in a gradient manner, the first gradient temperature is 260-400 ℃, the temperature is kept for 10-60min, the temperature is increased to the second gradient of 450-560 ℃ along with the furnace, and the temperature is kept for 0.5-3h, so that the Cu-Cr-Nb alloy with high strength, high plasticity and high conductivity is obtained.
2. The method of improving the strength and electrical conductivity of a Cu-Cr-Nb alloy as set forth in claim 1, wherein: the alloy melt prepared by smelting in the step (1) is guided into a close coupling gas atomization furnace through a guide pipe at the flow speed of 3.5-4kg/min, the atomization temperature is controlled at 1600-1900 ℃, the pressure of a powder making furnace is controlled at 0.22-0.23bar, the pressure of an atomization medium is controlled at 3.5-5.5MPa, the particle size of Cu-Cr-Nb alloy powder obtained by powder sieving is 15-67 mu m, D10 is 15-25 mu m, D50 is 27-33 mu m, and D90 is 40-55 mu m.
3. The method of improving the strength and electrical conductivity of a Cu-Cr-Nb alloy as set forth in claim 1, wherein: the drying temperature of the selected alloy powder is 80-100 ℃, the drying time is 1-2h, and the drying is carried out in a vacuum atmosphere; and (3) packaging alloy powder: vacuumizing, filling reducing protective gas with hydrogen content of 1-3% and argon content not less than 97%, and packaging.
4. The method of improving the strength and electrical conductivity of a Cu-Cr-Nb alloy as set forth in claim 1, wherein: the Cu-Cr-Nb alloy prepared by the SLM has the tensile strength of 370-399MPa, the microhardness of 120-139HV, the electric conductivity of 20-25 percent IACS and the elongation of 35-41 percent at room temperature.
5. The method of improving the strength and electrical conductivity of a Cu-Cr-Nb alloy as set forth in claim 1, wherein: and (4) in the step (4), the first aging cooling mode is water cooling or air cooling, and the second aging cooling mode is air cooling.
6. The method of improving the strength and electrical conductivity of a Cu-Cr-Nb alloy as set forth in claim 1, wherein: after the Cu-Cr-Nb alloy prepared by the SLM in the step (4) is subjected to heat treatment, the room-temperature tensile strength is not lower than 623MPa, the microhardness is not lower than 217HV, the elongation is not lower than 27%, and the electric conductivity is not lower than 74% IACS; the tensile strength at 700 ℃ is 145-155 MPa.
7. The method of improving the strength and electrical conductivity of a Cu-Cr-Nb alloy as set forth in claim 1, wherein: when the Cr content in the Cu-Cr-Nb alloy powder is 0.71wt% and the Nb content is 0.11wt%, the tensile strength of the product obtained after heat treatment is 623MPa, the microhardness is 217HV, the elongation is 27%, and the electric conductivity is 84% IACS.
8. The method of claim 1, wherein when the Cr content of the Cu-Cr-Nb alloy powder is 1.58wt% and the Nb content is 1.36wt%, the tensile strength of the product after heat treatment is 635MPa, the microhardness is 221HV, the elongation is 28%, and the electrical conductivity is 81% IACS.
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