Composite reinforced dispersion copper and profile and preparation method thereof

Abstract

This invention provides a composite reinforced dispersed copper, a profile, and a preparation method. The preparation method of the composite reinforced dispersed copper includes: S1, melting electrolytic copper, an aluminum source, and a chromium source and / or a zirconium source, and then atomizing them using high-purity nitrogen as the atomizing medium to obtain copper alloy composite powder. The copper alloy composite powder contains 0.1~1wt% Al, 0~2wt% Cr, 0~0.5wt% Zr, and the balance is Cu, wherein the contents of Cr and Zr are not simultaneously 0; S2, subjecting the copper alloy composite powder to oxygenation treatment at 200~500℃ for 1~4h to obtain oxygenated powder; S3, subjecting the oxygenated powder to internal oxidation reaction at 600~900℃ for 2~6h to obtain oxygen-containing dispersed copper composite powder; S4, reducing the oxygen-containing dispersed copper composite powder by heating it to 600℃-700℃ in a hydrogen atmosphere for 1~3h. The product prepared by this invention has in-situ generated dispersed Al2O3 particles with fine particle size and uniform distribution, and in-situ generated nanoscale precipitated particles with small particle size and uniform dispersion distribution, which have significant advantages in terms of elongation and conductivity.

Description

Technical Field

[0001] This invention relates to the field of metal composite materials technology, and more specifically, to a composite reinforced dispersed copper, a profile, and a preparation method thereof. Background Technology

[0002] Al2O3 dispersion-strengthened copper is considered a novel functional material with great development potential and application prospects due to its advantages such as high strength, high softening temperature, and good electrical and thermal conductivity. Currently, it is mainly prepared by internal oxidation method, that is, Cu-Al alloy is first atomized into powder, mixed with an oxidant (such as Cu2O), and then Al is internally oxidized at high temperature to generate nano-Al2O3 dispersion phase, which is then reduced and densified to obtain the final product.

[0003] As the application scope of dispersed copper materials continues to expand, the original material properties can no longer meet the needs of the high-end market, and dispersed copper materials with higher comprehensive performance are constantly being developed. For example, Chinese patent application number 201910056095.1 discloses a high-performance dispersed copper alloy, which contains Al2O3 0.04-0.9% by mass, Cr 0.1-1.0%, and the balance being copper. The high-performance dispersed copper alloy prepared by this scheme has both high conductivity and strength, but due to the large density difference between Cu-Al powder (density about 7.8 g / cm³) and Cu-Cr powder (density about 8.6 g / cm³), component segregation is prone to occur during mechanical mixing, resulting in poor uniformity of the final product performance, low elongation, and easy cracking due to local performance deviations during subsequent deep processing (such as cold forging and drawing), resulting in a low final yield; further increasing the Al2O3 or Cr content will further aggravate the segregation problem.

[0004] Furthermore, Chinese patent application number 202310068183.X discloses a nano-dispersion strengthened copper alloy and its preparation method and application, including the following steps: S1, taking Cu-Al alloy powder and preparing Cu-Al2O3 dispersed copper powder through internal oxidation and reduction; S2, mixing the Cu-Al2O3 dispersed copper powder obtained in step S1 with Cr powder to obtain a composite powder, pressing it into shape, hot-pressing and sintering, encapsulating it, and then performing an aging treatment; wherein, the hot-pressing and sintering temperature is 900℃-1070℃, the pressure is 40MPa-80MPa, and the time is 2h-8h. This method can improve the electrical conductivity of the alloy, but due to the different densities of Cr powder and Cu-Al2O3, the powder mixing will be uneven, resulting in uneven material properties, low elongation, and easy cracking during processing. Summary of the Invention

[0005] The problem solved by this invention is that the elongation is low due to the insufficient uniformity of existing high-performance composite reinforced dispersed copper.

[0006] To address the above problems, this invention provides a method for preparing composite reinforced dispersed copper, comprising:

[0007] Step S1: After melting electrolytic copper, aluminum source, chromium source and / or zirconium source, high-purity nitrogen is used as the atomizing medium for gas atomization to obtain copper alloy composite powder. The copper alloy composite powder contains 0.1~1wt% Al, 0~2wt% Cr, 0~0.5wt% Zr, and the balance is Cu, wherein the contents of Cr and Zr are not both 0.

[0008] Step S2: Oxygen-coated powder is subjected to oxygen treatment at 200~500℃ for 1~4 hours to obtain oxygen-coated powder;

[0009] Step S3: The oxygen-containing powder is subjected to an internal oxidation reaction at 600~900℃ for 2~6 hours to obtain oxygen-containing dispersed copper composite powder;

[0010] Step S4: Reduce the oxygen-containing dispersed copper composite powder by heating it to 600℃-700℃ in a hydrogen atmosphere for 1-3 hours to obtain dispersed copper composite powder.

[0011] Preferably, the aluminum source in step S1 is a copper-aluminum master alloy, the chromium source is a copper-chromium master alloy, and the zirconium source is a copper-zirconium master alloy; the smelting adopts medium-frequency induction smelting, and the smelting time is 50~90min.

[0012] Preferably, the oxygen supply treatment in step S2 is carried out in air or an atmosphere with an oxygen content ≥21%, and the internal oxidation reaction in step S3 is carried out in a vacuum or an inert atmosphere.

[0013] This invention also provides a method for preparing composite reinforced dispersed copper profiles, comprising: placing the above-mentioned dispersed copper composite powder in an isostatic pressing sleeve, increasing the pressure to 350-450 MPa at a pressurization rate of 1-15 MPa / min, and holding the pressure for 10-15 min to obtain an ingot; vacuum sealing the ingot, and then extruding it at 900-1000℃ at an extrusion ratio of 5-50 times to obtain a rod or profile; and subjecting the rod or profile to solution treatment and aging treatment in sequence to obtain the final product.

[0014] Preferably, the solution treatment is performed by holding at 900~1000℃ for 1~5 hours followed by water quenching, and the aging treatment is performed by holding at 400~500℃ for 1~20 hours followed by air cooling.

[0015] The present invention also provides a composite reinforced dispersed copper profile, which is prepared by a method for preparing composite reinforced dispersed copper profiles.

[0016] Preferably, the composite reinforced dispersed copper profile contains 0.1~1.2wt% Al2O3, 0~2wt% Cr, 0~0.5wt% Zr, and the balance is Cu.

[0017] Preferably, the average size of Al2O3 particles in the composite reinforced dispersed copper profile is ≤10nm, the average spacing between adjacent Al2O3 particles is <50nm, and the composite reinforced dispersed copper contains a nanoscale precipitate phase with a size of 5~20nm.

[0018] Compared with the prior art, the composite reinforced dispersed copper profile and preparation method described in this invention have the following beneficial effects: 1) Dispersed Al2O3 particles are generated in situ, with fine particle size and uniform distribution; tests show that the average distance between dispersed Al2O3 particles in the Cu-1.2%Al2O3 product is <50nm, and the dispersion distribution is uniform; at the same time, since the ingot is reduced in high-purity hydrogen at only 600-700℃, the heat treatment temperature is low, so the dispersed Al2O3 particles will not grow abnormally, and the size of the Al2O3 particles is all below 10nm; 2) Nanoscale precipitated Cu2Cr and ZrCu phase particles are generated in situ, with a particle size of 5~20nm, and the dispersion distribution is uniform; 3) The finished product has a relative density of over 99%, a tensile strength of 500-650MPa, an elongation of 16~22%, a hardness (HRB) of 81.0-85, and a conductivity of 81-95%IACS, exhibiting excellent comprehensive performance. Detailed Implementation

[0019] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below. Without conflict, the technical features of the embodiments of the present invention can be combined with each other.

[0020] Dispersion strengthening refers to the method of strengthening materials by adding uniform, fine oxide particles into a metal matrix to impede dislocation movement by pinning dislocations, grain boundaries, and subgrain boundaries. For example, Al2O3 dispersion-strengthened copper consists of uniformly distributed, fine Al2O3 particles in a copper matrix. It exhibits high strength, high softening temperature, and excellent electrical and thermal conductivity, and has found applications in numerous high-tech fields such as high-power microwave tubes, lead frames for very large-scale integrated circuits, overhead lines for high-speed rail transportation, high-pulse magnetic field conductors for wires, crystallizers for continuous casting machines, and resistance welding electrodes. Existing dispersion-strengthened copper typically involves separately atomizing Cu-Al and Cu-Cr powders, then mixing them, followed by hot extrusion, cold forging, and aging. However, due to differences in powder density, uneven mixing is prone to occur, resulting in low elongation of the final material and susceptibility to cracking during processing. Therefore, the applicant proposes the following technical solution:

[0021] This application provides a method for preparing uniform, high-performance composite reinforced dispersed copper. Using CuAl-Cr, CuAl-Zr, or CuAl-Cr-Zr alloy powder prepared by atomization with high-purity nitrogen as raw material, the powder is internally oxidized and reduced after oxygen addition to obtain Cu / γ-Al2O3-Cr, Cu / γ-Al2O3-Zr, or Cu / γ-Al2O3-Cr-Zr powder. The powder is then loaded into an isostatic pressing sleeve for isostatic pressing to obtain a dense ingot. This ingot is then reduced in high-purity hydrogen at 600-700℃ for 2-6 hours. Finally, the ingot is placed in a mold for hot extrusion to prepare a dense composite reinforced dispersed copper rod or profile. Specifically, the method includes:

[0022] S1. Preparation of gas-atomized composite Cu-Al-Cr, Cu-Al-Zr, and Cu-Al-Cr-Zr powders

[0023] The powder is produced by atomization with high-purity nitrogen and smelted in a medium-frequency melting furnace. High-purity oxygen-free electric copper, copper-aluminum master alloy, copper-chromium master alloy, and copper-zirconium master alloy are added to the furnace and smelted for 50-90 minutes. Then, the powder is produced by atomization with high-purity nitrogen, dried, and sieved into Cu-Al-Cr, Cu-Al-Zr, or Cu-Al-Cr-Zr powder for later use. The Al content is 0.1-1 wt%, the Cr content is 0.1-2 wt%, and the Zr content is 0.01-0.5%.

[0024] S2, oxygen supply

[0025] Cu-Al-Cr, Cu-Al-Zr, or Cu-Al-Cr-Zr powders are placed in an oxygen mixing furnace and heated to 200~500℃ to mix oxygen, thus obtaining oxygen-mixed powder.

[0026] S3, internal oxidation

[0027] The oxygen-containing powder is placed in a vacuum sintering furnace and heated to 600~900℃ under vacuum for internal oxidation, ultimately obtaining Cu / γ-Al2O3-Cr or Cu / γ-Al2O3-Zr or Cu / γ-Al2O3-Cr-Zr oxygen-containing dispersed copper composite powder.

[0028] S4, Restore

[0029] The internal oxide powder is placed in a hydrogen sintering furnace and heated to 600~700℃ under hydrogen for reduction, finally obtaining Cu / γ-Al2O3-Cr or Cu / γ-Al2O3-Zr or Cu / γ-Al2O3-Cr-Zr dispersed copper composite powder.

[0030] S5, CIP processing

[0031] The Cu / γ-Al2O3-Cr, Cu / γ-Al2O3-Zr, or Cu / γ-Al2O3-Cr-Zr powders in S3 are placed in an isostatic pressing sleeve. The pressing process is as follows: pressurization rate: 1-5 MPa / min, maximum pressure 350-450 MPa, holding time 10-15 minutes, to form a relatively dense ingot.

[0032] S6, Hot Extrusion

[0033] After the ingots processed in S5 are vacuum-sealed, they are extruded at 600~1000℃ with a specific heat of 5~50 times to form composite reinforced dispersed copper rods or profiles.

[0034] S7, Heat Treatment

[0035] The bar or profile treated in S6 is solution treated at 900~1000℃ for 1~5h, then water quenched and air-cooled for aging at 400~500℃ for 1~20h to obtain composite reinforced dispersed copper bar or profile.

[0036] Example 1

[0037] A method for preparing composite reinforced dispersed copper, wherein the composite reinforced dispersed copper comprises 1.2 wt% Al2O3, 2 wt% Cr, and the balance being copper, comprising the following steps:

[0038] Step S1: Gas atomization powder production

[0039] The powder was produced by atomization with high-purity nitrogen and smelted in a medium-frequency melting furnace. High-purity oxygen-free electric copper, copper-aluminum master alloy with 50% aluminum content, and copper-chromium master alloy with 10% chromium content were added to the furnace in a weight ratio of 100:1.5:24. The mixture was smelted for 90 minutes, then atomized with high-purity nitrogen to produce powder. The powder was dried and sieved to obtain Cu-Al-Cr alloy powder for later use.

[0040] Step S2, Oxygen Preparation

[0041] Cu-Al-Cr powder was placed in an oxygen-mixing furnace and mixed with oxygen at 500℃ for 2 hours to obtain oxygen-mixed powder.

[0042] Step S3, Internal Oxidation

[0043] The oxygen-containing powder was placed in a vacuum sintering furnace and sintered at 650℃ for 5 hours to obtain oxygen-containing Cu / γ-Al2O3-Cr composite powder.

[0044] Step S4, Restore

[0045] Oxygen-containing Cu / γ-Al2O3-Cr composite powder was placed in a hydrogen reduction furnace and heated to 600℃ for 2 hours under a hydrogen atmosphere to obtain Cu / γ-Al2O3-Cr powder.

[0046] Step S5, Cold Isostatic Pressing (CIP)

[0047] Cu / γ-Al2O3-Cr powder was placed in an isostatic pressing chamber and pressed at a pressurization rate of 15 MPa / min, a maximum pressure of 350 MPa, and a holding time of 10 minutes to form a relatively dense ingot.

[0048] Step S6, Hot Extrusion

[0049] The CIP-treated billet is vacuum-sealed and placed in a heating furnace, where it is extruded at 950°C with a 5x extrusion ratio to obtain a dense bar.

[0050] Step S7, Heat Treatment

[0051] The bar was solution-quenched at 900℃ for 5 hours, followed by aging at 500℃ for 20 hours and then air-cooled to obtain the precipitated phase in the material.

[0052] Example 2

[0053] A method for preparing composite reinforced dispersed copper, wherein the composite reinforced dispersed copper comprises 0.5 wt% Al2O3, 0.01 wt% Zr, and the balance being copper, comprising the following steps:

[0054] Step S1: Gas atomization powder production

[0055] The powder was produced by atomization with high-purity nitrogen and smelted in a medium-frequency melting furnace. High-purity oxygen-free copper, copper-aluminum master alloy with 50% aluminum content, and copper-zirconium master alloy with 50% zirconium content were added to the furnace in a weight ratio of 100:0.5:0.02 and smelted for 50 minutes. Then, the powder was produced by atomization with high-purity nitrogen, dried, and sieved to obtain Cu-Al-Zr alloy powder for later use.

[0056] Step S2, Oxygen Preparation

[0057] Cu-Al-Zr powder was placed in an oxygen-mixing furnace and mixed with oxygen at 300℃ for 1.5 hours to obtain oxygen-mixed powder.

[0058] Step S3, Internal Oxidation

[0059] The oxygen-containing powder was placed in a vacuum sintering furnace and sintered at 900℃ for 2.5 h to obtain oxygen-containing Cu / γ-Al2O3-Zr composite powder.

[0060] Step S4, Restore

[0061] Oxygen-containing Cu / γ-Al2O3-Zr composite powder was placed in a hydrogen reduction furnace and heated to 700℃ for 1.5 h under a hydrogen atmosphere to obtain Cu / γ-Al2O3-Zr powder.

[0062] Step S5, Cold Isostatic Pressing (CIP)

[0063] Cu / γ-Al2O3-Zr powder was placed in an isostatic pressing chamber and pressed at a pressurization rate of 1 MPa / min, a maximum pressure of 450 MPa, and a holding time of 15 minutes to form a relatively dense ingot.

[0064] Step S6, Hot Extrusion

[0065] The CIP-treated billet is vacuum-sealed and placed in a heating furnace, where it is extruded at 950°C with a 5x extrusion ratio to obtain a dense bar.

[0066] Step S7, Heat Treatment

[0067] The bar was solution-quenched at 1000℃ for 1 hour, followed by aging at 400℃ for 2 hours and air-cooled to obtain the precipitated phase in the material.

[0068] Example 3

[0069] A method for preparing composite reinforced dispersed copper, wherein the composite reinforced dispersed copper comprises, by mass percentage, 0.2 wt% Al2O3, 0.5 wt% Cr, 0.5 wt% Zr, with the balance being copper, and includes the following steps:

[0070] Step S1: Gas atomization powder production

[0071] The powder was produced by atomization with high-purity nitrogen and smelted in a medium-frequency melting furnace. High-purity oxygen-free electric copper, copper-aluminum master alloy with 50% aluminum content, copper-chromium master alloy with 10% chromium content, and copper-zirconium master alloy with 50% zirconium content were added to the furnace in a weight ratio of 100:0.21:5.25:1.05 and smelted for 70 minutes. Then, the powder was produced by atomization with high-purity nitrogen, dried, and sieved to obtain Cu-Al-Cr-Zr alloy powder for later use.

[0072] Step S2, Oxygen Preparation

[0073] Cu-Al-Cr-Zr powder was placed in an oxygen mixing furnace and mixed with oxygen at 400℃ for 2 hours to obtain oxygen-mixed powder.

[0074] Step S3, Internal Oxidation

[0075] The oxygen-containing powder was placed in a vacuum sintering furnace and sintered at 800℃ for 3.5 h to obtain oxygen-containing Cu / γ-Al2O3-Cr-Zr composite powder.

[0076] Step S4, Restore

[0077] Oxygen-containing Cu / γ-Al2O3-Cr-Zr composite powder was placed in a hydrogen reduction furnace and heated to 650℃ for 2 hours under a hydrogen atmosphere to obtain Cu / γ-Al2O3-Cr-Zr powder.

[0078] Step S5, Cold Isostatic Pressing (CIP)

[0079] Cu / γ-Al2O3-Cr-Zr powder was placed in an isostatic pressing chamber and pressed at a pressurization rate of 2.5 MPa / min, a maximum pressure of 400 MPa, and a holding time of 15 minutes to form a relatively dense ingot.

[0080] Step S6, Hot Extrusion

[0081] The CIP-treated billet is vacuum-sealed and placed in a heating furnace, where it is extruded at 800°C with an extrusion ratio of 25 to obtain a dense bar.

[0082] Step S7, Heat Treatment

[0083] The bar was solution-quenched in water at 950℃ for 2.5h, and then aged at 450℃ for 10h and air-cooled to obtain the precipitated phase in the material.

[0084] Comparative Example 1

[0085] The process steps are the same as in Example 1, except that a copper-chromium master alloy is not added in step S1.

[0086] Comparative Example 2

[0087] The process steps are the same as in Example 2, except that copper-zirconium master alloy is not added in step S1.

[0088] Comparative Example 3

[0089] The process steps are the same as in Example 3, except that copper-chromium master alloy and copper-zirconium master alloy are not added in step S1.

[0090] The relative density, tensile strength, elongation, hardness, and conductivity of the composite reinforced dispersed copper prepared in Examples 1-3 and Comparative Examples 1-3 were tested, and the results are shown in Table 1. The relevant testing methods are existing technologies and will not be described in detail here.

[0091] Table 1 Performance test results of composite reinforced dispersed copper

[0092] sample relative density Tensile strength (MPa) elongation % Hardness HRB Conductivity %IACS Example 1 99.2 620 18 83 88 Example 2 99.3 550 22 81 90 Example 3 99.1 580 21 82 95 Comparative Example 1 98.7 560 16 80 83 Comparative Example 2 98.8 530 18 78 86 Comparative Example 3 98.7 480 18 74 92

[0093] As shown in Table 1, the elongation rates (18%~22%) of Examples 1-3 are all higher than those of the corresponding comparative examples. While avoiding powder segregation, the in-situ uniform distribution of Al2O3 dispersed phase and Cr / Zr precipitate phase is achieved, indicating that this application still has good compositional uniformity after the addition of Cr / Zr, thus maintaining the elongation rate at a high level. The conductivity of Example 3 is as high as 95% IACS, which is significantly higher than other samples and even exceeds that of Comparative Example 3 without Cr and Zr. This shows that after adding an appropriate amount of Cr and Zr, the scattering of solid solution atoms can be effectively reduced by optimizing the aging precipitation behavior. It has obvious advantages in terms of compositional uniformity and conductivity and has good prospects for industrial application.

[0094] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for preparing composite reinforced dispersed copper, characterized in that, include: Step S1: After melting electrolytic copper, aluminum source, chromium source and / or zirconium source, high-purity nitrogen is used as the atomizing medium for gas atomization to obtain copper alloy composite powder. The copper alloy composite powder contains 0.1~1wt% Al, 0~2wt% Cr, 0~0.5wt% Zr, and the balance is Cu, wherein the contents of Cr and Zr are not both 0. Step S2: Oxygen-coated powder is subjected to oxygen treatment at 200~500℃ for 1~4 hours to obtain oxygen-coated powder; Step S3: The oxygen-containing powder is subjected to an internal oxidation reaction at 600~900℃ for 2~6 hours to obtain oxygen-containing dispersed copper composite powder; Step S4: Reduce the oxygen-containing dispersed copper composite powder by heating it to 600℃-700℃ in a hydrogen atmosphere for 1-3 hours to obtain dispersed copper composite powder.

2. The method for preparing composite reinforced dispersed copper according to claim 1, characterized in that, The aluminum source in step S1 is a copper-aluminum master alloy, the chromium source is a copper-chromium master alloy, and the zirconium source is a copper-zirconium master alloy; the smelting adopts medium-frequency induction smelting, and the smelting time is 50~90min.

3. The method for preparing composite reinforced dispersed copper according to claim 1, characterized in that, The oxygen supply process described in step S2 is carried out in air or an atmosphere with an oxygen content of ≥21%, and the internal oxidation reaction described in step S3 is carried out in a vacuum or an inert atmosphere.

4. A method for preparing a composite reinforced dispersed copper profile, characterized in that, include: The dispersed copper composite powder obtained by the preparation method according to any one of claims 1 to 3 is placed in an isostatic pressing sleeve, and the pressure is increased to 350 to 450 MPa at a pressurization rate of 1 to 15 MPa / min, and the pressure is held for 10 to 15 min to obtain an ingot; after vacuum sealing the ingot, it is extruded at 600 to 1000℃ at an extrusion ratio of 5 to 50 times to obtain a bar or profile; the bar or profile is subjected to solution treatment and aging treatment in sequence to obtain the final product.

5. The method for preparing the composite reinforced dispersed copper profile according to claim 4, characterized in that, The solution treatment is performed by holding at 900~1000℃ for 1~5 hours followed by water quenching, and the aging treatment is performed by holding at 400~500℃ for 1~20 hours followed by air cooling.

6. A composite reinforced dispersion copper profile, characterized in that, It is prepared by the method for preparing composite reinforced dispersed copper profiles as described in claim 4 or 5.

7. The composite reinforced dispersion copper profile according to claim 6, characterized in that, The composite reinforced dispersed copper profile contains 0.1~1.2wt% Al2O3, 0~2wt% Cr, 0~0.5wt% Zr, and the balance is Cu.

8. The composite reinforced dispersion copper profile according to claim 7, characterized in that, The average size of Al2O3 particles in the composite reinforced dispersed copper profile is ≤10nm, the average spacing between adjacent Al2O3 particles is <50nm, and the composite reinforced dispersed copper contains nanoscale precipitates with a size of 5~20nm.