Aluminum-rare earth alloy high-strength high-conductivity heat-resistant conductor material with core-shell structure and preparation method thereof

Abstract

The application discloses a high-strength high-conductivity heat-resistant high-elongation low-cost aluminum-rare earth alloy conductor material with a core-shell structure and a preparation method thereof, and belongs to the technical field of non-ferrous metal material processing, and aims to solve the technical problems that the strength, conductivity and elongation of the existing aluminum-rare earth alloy conductor are difficult to be considered simultaneously, and the large amount of heavy rare earth leads to high cost. The material is composed of Ce 0.15-0.20%, Er 0.08-0.12%, Yb 0.05-0.08%, Zr 0.15-0.18%, Fe 0.10-0.13% and the balance of Al, and the microstructure contains a core-shell nano precipitated phase (the core RE is greater than or equal to 90%, and the shell Zr is greater than or equal to 85%) with a rich rare earth core and a rich zirconium shell and an Al 13 Fe4 dispersed phase with an equivalent spherical average diameter of less than or equal to 50 nm. The application controls the core-shell structure through a compound process of differential two-stage homogenization, solid solution aging and annealing, the material has a tensile strength greater than or equal to 182 MPa, a conductivity greater than or equal to 61.5% IACS, an elongation greater than or equal to 22%, a 300 DEG C strength residual rate greater than or equal to 92%, the cost is reduced by 25-30% compared with similar products, and the material is suitable for the fields of power transmission and electrical equipment.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal material processing technology, specifically relating to a high-strength, high-conductivity, high-elongation, low-cost aluminum rare earth alloy conductor material with a core-shell structure and its preparation method, which can be applied to fields such as power transmission and electrical equipment. Background Technology

[0002] With the increasing application of aluminum instead of copper in the power transmission field, rare earth aluminum alloy cables have attracted widespread attention due to their low cost and light weight. Existing technologies, such as the scheme disclosed in CN102262913B, achieve reinforcement by adding Fe (0.4-1.5%) and rare earth elements (0.3-3%) to form micron / submicron-scale intermetallic compounds. However, while improving strength, such technologies often struggle to simultaneously maintain conductivity and elongation.

[0003] In recent years, strengthening with nano-precipitates has become a cutting-edge approach to overcome this bottleneck. For example, CN121380687A proposes improving performance by forming Al3(RE,Zr) nano-precipitates. However, research has found that single Al3(RE,Zr) nano-precipitates suffer from uneven distribution, resulting in limited improvement in elongation while enhancing strength. Furthermore, existing technologies largely rely on high heavy rare earth elements, leading to high production costs and becoming a key factor restricting industrialization.

[0004] Therefore, how to achieve high strength and high conductivity while obtaining excellent elongation and effectively controlling production costs remains a problem that urgently needs to be solved in this field. Summary of the Invention

[0005] Purpose of the invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-strength, high-conductivity, high-elongation, low-cost aluminum rare earth alloy conductor material with a core-shell structure and its preparation method, achieving an excellent balance of strength, conductivity, elongation, heat resistance and economy.

[0007] Technical solution

[0008] First aspect: Aluminum rare earth alloy conductor materials

[0009] A high-strength, high-conductivity, high-elongation, low-cost aluminum-rare-earth alloy conductor material with a core-shell structure, composed of the following components by mass percentage:

[0010] 1. Cerium (Ce): 0.15–0.20%

[0011] 2. Erbium (Er): 0.08–0.12%

[0012] 3. Ytterbium (Yb): 0.05–0.08%

[0013] 4. Zirconium (Zr): 0.15–0.18%

[0014] 5. Iron (Fe): 0.10–0.13%

[0015] 6. The balance is aluminum (Al) and unavoidable impurities.

[0016] Furthermore, the microstructure of the material has the following characteristics:

[0017] 1. Core-shell structured nanoprecipitates: Al3(RE,Zr) composite nanoprecipitates, comprising a rare earth element-rich core (Ce, Er, Yb) and a Zr-rich shell; the sum of the atomic concentrations of rare earth elements in the core accounts for more than 90% of the total number of atoms in the core of the precipitate, and the atomic concentration of Zr in the shell accounts for more than 85% of the total number of atoms in the shell of the precipitate.

[0018] 2. Nanoscale dispersed phase: This refers to nanoscale Al particles encapsulated or pinned by the core-shell structured nanoscale precipitates. 13 The Fe4 dispersed phase has an equivalent spherical average diameter of no more than 50 nm.

[0019] Second aspect: Preparation method

[0020] A method for preparing the above-mentioned aluminum rare earth alloy conductor material includes the following steps:

[0021] 1. Melting and casting: Prepare raw materials according to the stated composition ratio, melt them under a protective atmosphere, and then cast them into ingots.

[0022] 2. Differentiated two-stage homogenization treatment:

[0023] (1) First-stage homogenization: The ingot is heated to 420-425°C and held for 4.5-5.5 hours to promote the initial diffusion of rare earth elements and the formation of Al3RE phase nuclei;

[0024] (2) Second-stage homogenization: The temperature is raised to 540–545℃ and held for 8–10 hours to promote the diffusion of Zr elements to the periphery of the primary Al3RE phase, forming a Zr-rich shell and promoting Al... 13 Nanostructuring of Fe4 phase.

[0025] 3. Hot deformation processing: The homogenized ingot is heated to 460-500℃ for hot extrusion or hot rolling to produce wire rod.

[0026] 4. Solution treatment and aging treatment:

[0027] (1) Solution treatment: Heat the wire blank to 560-565℃, hold for 1.5-2.0 hours, and then quench it in water to room temperature at a cooling rate of ≥80℃ / min;

[0028] (2) Aging treatment: The solution-treated wire blank is kept at 242-248℃ for 6.5-7.5 hours to further optimize and stabilize the core-shell structure nano-precipitates.

[0029] 5. Annealing treatment: Heat the aged wire to 310-330℃ and hold for 2.0-3.0 hours to eliminate the internal stress caused by work hardening.

[0030] 6. Cold working: The annealed wire is cold drawn to obtain the conductor of the required specifications.

[0031] Beneficial effects

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. A unique core-shell dual-phase nanostructure was constructed: Through a differentiated two-stage homogenization process, a heterogeneous distribution of RE and Zr elements at the nanoscale was achieved, forming a nanoprecipitated phase of "RE-rich core + Zr-rich shell". The RE-rich core achieves strong precipitation enhancement, while the Zr-rich shell can effectively suppress the coarsening of the precipitated phase and reduce electron scattering, laying the structural foundation for subsequent performance balance.

[0034] 2. Excellent comprehensive performance: The material's tensile strength can reach over 182 MPa, conductivity can reach over 61.5% IACS, elongation can reach over 22%, and the strength retention rate after holding at 300℃ for 1 hour can reach over 92%. Core-shell precipitates and nano-sized Al 13 The synergistic effect of the Fe4 dispersed phase not only enhances strength through dislocation pinning, but also reduces electron scattering and stress concentration due to the small size and uniform distribution of the precipitates, thus achieving a simultaneous improvement in strength, conductivity, and elongation. The Zr-rich shell also improves the thermal stability of the precipitates, resulting in excellent heat resistance of the material.

[0035] 3. Significantly reduced costs: By replacing some heavy rare earth elements with high-abundance, low-cost cerium, and with optimized heat treatment processes, the overall production cost is reduced by approximately 25-30% compared to similar high-end products. The use of high-abundance Ce significantly reduces the cost of rare earth raw materials, while the differentiated two-stage homogenization process shortens the overall heat treatment time and reduces process energy consumption, achieving cost reduction in both raw materials and processes. Attached Figure Description

[0036] Figure 1 Schematic diagram of a core-shell structured nanoprecipitated phase. Figure 1This is a schematic diagram of the core-shell nanoprecipitated phase structure of the aluminum rare earth alloy conductor material prepared in Example 1 of the present invention. In the figure: 1. Rare earth rich core (Ce / Er / Yb≥90%); 2. Al 13 Fe4 dispersed phase (≤50nm); 3. Zirconium-rich outer shell (Zr≥85%); 4. Al matrix. Scale bar is 50nm;

[0037] Figure 2 Comparison chart of tensile strength and electrical conductivity. Figure 2 This is a comparison chart of the tensile strength and electrical conductivity of Examples 1-3 and Comparative Example 1 of the present invention;

[0038] Figure 3 Elongation comparison chart. Figure 3 This is a bar chart comparing the elongation rates of Examples 1-3 and Comparative Example 1 of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in further detail below with reference to the accompanying drawings and embodiments. However, the following embodiments are only used to explain this invention and do not constitute a limitation on the scope of protection of this invention.

[0040] Test method description:

[0041] The performance tests of the embodiments and comparative examples of this invention were all conducted in accordance with the following standards:

[0042] 1. Tensile strength: Tested according to GB / T228.1-2021 "Metallic materials - Tensile testing - Part 1: Test method at room temperature";

[0043] 2. Conductivity: Tested according to GB / T351-2019 "Methods for Measurement of Resistivity of Metallic Materials";

[0044] 3. Elongation: Tested according to GB / T228.1-2021;

[0045] 4. Heat resistance (300℃ / 1h strength residual rate): Tested according to GB / T20957.1-2007 "High temperature tensile test method".

[0046] Raw material description:

[0047] The purity of the raw materials used in the embodiments of the present invention is as follows:

[0048] 1. Pure Al: Purity ≥ 99.99%;

[0049] 2. Al-10%Ce, Al-5%Er, Al-5%Yb, Al-4%Zr, and Al-10%Fe master alloys: all with a purity ≥99.5%.

[0050] Example 1

[0051] 1. Batching: Take pure Al, Al-10%Ce, Al-5%Er, Al-5%Yb, Al-4%Zr, and Al-10%Fe master alloy, and mix them according to the final composition of Ce 0.18%, Er 0.10%, Yb 0.06%, Zr 0.16%, Fe 0.12%, with the balance being Al.

[0052] 2. Melting and casting: Melting is carried out at 750℃ under argon protection, and after being stirred evenly, it is cast into ingots.

[0053] 3. Differentiated two-stage homogenization: The ingot is placed in a homogenization furnace, first held at 423℃ for 5.0 hours, then heated to 542℃ and held for 9.0 hours, and then removed from the furnace and air-cooled.

[0054] 4. Hot Deformation: The homogenized ingot is heated to 480℃ and hot extruded to form... Wire rod blank.

[0055] 5. Solution treatment and aging: The wire rod was solution treated at 562℃ for 1.8 hours and then water quenched; subsequently, it was aged at 245℃ for 7.0 hours.

[0056] 6. Annealing treatment: Hold the aged wire at 320℃ for 2.5 hours, then cool it to room temperature in the furnace.

[0057] 7. Cold working: Cold drawing the annealed wire to... Specification.

[0058] 8. Performance Testing: The obtained conductor was tested and found to have a tensile strength of 184 MPa, a conductivity of 61.6% IACS, an elongation of 23.2%, and a strength retention rate of 92.8% after 300℃ / 1h. Its microstructure is as follows... Figure 1 As shown, a large number of diffusely distributed core-shell structured nanoprecipitates are visible.

[0059] Example 2

[0060] 1. Ingredients: The ingredients are prepared according to the final composition of Ce 0.15%, Er 0.12%, Yb 0.05%, Zr 0.17%, Fe 0.11%, and the balance Al.

[0061] 2. Melting and casting: Same as in Example 1.

[0062] 3. Differentiated two-stage homogenization: heat at 421℃ for 5.5 hours, then heat at 541℃ for 8.5 hours.

[0063] 4. Heat distortion: Same as in Example 1.

[0064] 5. Solution treatment and aging: Solution treatment at 561℃ for 1.5 hours followed by water quenching; aging treatment at 243℃ for 7.2 hours.

[0065] 6. Annealing treatment: Hold at 315℃ for 2.8 hours, then cool with the furnace.

[0066] 7. Cold processing: Same as in Example 1.

[0067] 8. Performance testing: Tensile strength is 182MPa, conductivity is 61.8% IACS, elongation is 23.8%, and the strength retention rate at 300℃ / 1h is 93.1%.

[0068] Example 3

[0069] 1. Ingredients: The ingredients are prepared according to the final composition of Ce 0.20%, Er 0.08%, Yb 0.08%, Zr 0.15%, Fe 0.13%, and the balance Al.

[0070] 2. Melting and casting: Same as in Example 1.

[0071] 3. Differentiated two-stage homogenization: heat at 424℃ for 4.8 hours, then heat at 544℃ for 9.5 hours.

[0072] 4. Heat distortion: Same as in Example 1.

[0073] 5. Solution treatment and aging: Solution treatment at 564℃ for 2.0 hours followed by water quenching; aging treatment at 247℃ for 6.8 hours.

[0074] 6. Annealing treatment: Hold at 325℃ for 2.2 hours, then cool with the furnace.

[0075] 7. Cold processing: Same as in Example 1.

[0076] 8. Performance testing: Tensile strength is 185MPa, conductivity is 61.5% IACS, elongation is 22.5%, and the strength retention rate at 300℃ / 1h is 92.5%.

[0077] Comparative Example 1 (using the patented formula and process of CN102262913B)

[0078] 1. Ingredients: Refer to Example 1 of CN102262913B, and prepare the ingredients as follows: Fe 1.0%, rare earth (La / Ce mixture) 1.5%, Mg 0.1%, and the balance Al.

[0079] 2. Melting and casting: Same as in Example 1.

[0080] 3. Homogenization: Conventional single-stage homogenization treatment is adopted at a temperature of 500℃ for 10 hours.

[0081] 4. Heat distortion: Same as in Example 1.

[0082] 5. Solution treatment and aging: Following the process, after solution treatment at 550℃, artificial aging is performed.

[0083] 6. Cold processing: Same as in Example 1.

[0084] 7. Performance Testing: The obtained conductor was tested and found to have a tensile strength of 155 MPa, a conductivity of 59.0% IACS, an elongation of 35.2%, and a strength retention rate of approximately 80% at 300℃ for 1 hour. Its performance is comparable to that of the embodiments of the present invention. Figure 2 and Figure 3 As shown.

Claims

1. A high-strength, high-conductivity, high-elongation, low-cost aluminum-rare-earth alloy conductor material with a core-shell structure, characterized in that, It consists of the following components by mass percentage: Ce 0.15–0.20%, Er 0.08–0.12%, Yb 0.05–0.08%, Zr 0.15–0.18%, Fe 0.10–0.13%, with the balance being Al and unavoidable impurities.

2. The high-strength, high-conductivity, high-elongation, low-cost aluminum rare-earth alloy conductor material with a core-shell structure according to claim 1, characterized in that, The microstructure of the material comprises a core-shell structured nanoprecipitate and a nanoscale dispersed phase. The core-shell structured nanoprecipitate is an Al3(RE,Zr) composite nanoprecipitate, comprising a rare-earth-rich core and a Zr-rich shell. The sum of the atomic concentrations of rare-earth elements in the core accounts for more than 90% of the total number of atoms in the core, and the atomic concentration of Zr in the shell accounts for more than 85% of the total number of atoms in the shell. The nanoscale dispersed phase consists of nanoscale Al3(RE,Zr) particles encapsulated or pinned by the core-shell structured nanoprecipitate. 13 The Fe4 dispersed phase has an equivalent spherical average diameter of no more than 50 nm.

3. A method for preparing a high-strength, high-conductivity, high-elongation, low-cost aluminum rare-earth alloy conductor material with a core-shell structure as described in claim 1 or 2, characterized in that, Includes the following steps: Step 1, casting: Prepare materials according to the composition ratio, melt them under a protective atmosphere, and cast them into ingots; Step 2, Differentiated two-stage homogenization treatment: The ingot is subjected to the first stage homogenization treatment by heating to 420-425℃ and holding for 4.5-5.5 hours; then the second stage homogenization treatment is performed by heating to 540-545℃ and holding for 8.0-10 hours. Step 3, hot deformation processing: The homogenized ingot is heated to 460-500℃ for hot extrusion or hot rolling to produce wire rod. Step 4, Solution treatment and aging treatment: The wire blank is solution treated by heating to 560-565℃ and holding for 1.5-2.0 hours, then water quenched at a cooling rate of ≥80℃ / min; then aging treatment is performed by heating to 242-248℃ and holding for 6.5-7.5 hours. Step 5, Annealing treatment: Anneal the aged wire by heating it to 310-330℃ and holding it for 2.0-3.0 hours; Step 6, cold working: The annealed wire is cold drawn to obtain the conductor of the required specifications.

4. The preparation method according to claim 3, characterized in that, In step 2, the temperature of the first homogenization treatment is 422-424℃ and the holding time is 4.8-5.2 hours; the temperature of the second homogenization treatment is 541-543℃ and the holding time is 8.5-9.5 hours.

5. The preparation method according to claim 3, characterized in that, The solution treatment in step 4 is performed at a temperature of 561–563°C for 1.6–1.9 hours; the aging treatment is performed at a temperature of 243–247°C for 6.8–7.2 hours.

6. The preparation method according to claim 3, characterized in that, The annealing temperature in step 5 is 315–325°C, and the holding time is 2.2–2.8 hours.

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