A processing technology for nano WC particle reinforced aluminum-lithium alloy composite material

Abstract

The present invention discloses a processing technology for nano-WC particle reinforced aluminum-lithium alloy composite material, which belongs to the technical field of preparation of aluminum alloy hot processing materials. The high-strength and corrosion-resistant aluminum-lithium alloy material of the present invention contains Ce, nano-WC particles and cobalt; the preparation steps are: putting the raw materials into a ball mill and grinding them into powder, pressing them into sheets, polishing, melting and adding pure lithium, using electromagnetic stirring to make the composition uniform, pouring, and then undergoing two-stage homogenization treatment, hot rolling, solution treatment, cold rolling, hydrothermal treatment, and artificial aging treatment to obtain a high-strength and corrosion-resistant aluminum-lithium alloy material with a large amount of fine-grained organization and heterogeneous structure. The main precipitated phases are T1 (Al2CuLi) and θ' (Al2Cu) phases, wherein the T1 phase is the main strengthening phase of the Al‑Cu‑Li alloy. The high-strength and corrosion-resistant aluminum-lithium alloy material of the present invention has the characteristics of high strength, high hardness, good ductility and excellent mechanical properties.

Description

Technical Field

[0001] The invention relates to a processing technology for a nano WC particle reinforced aluminum-lithium alloy composite material, belonging to the technical field of aluminum alloy hot-working material preparation. Background Art

[0002] Aluminum-lithium alloy is a lightweight, high-strength, and highly rigid metal material with excellent mechanical properties and corrosion resistance. It is currently widely used in aerospace, automotive, high-speed train, and electronic equipment manufacturing. As industry's demand for lightweight, high-strength aluminum-lithium alloys continues to increase, research on methods to improve the strength of aluminum-lithium alloys is of great significance.

[0003] Chinese patent CN116179912A discloses a Ce-containing high-strength and toughness aluminum-lithium alloy and its preparation method in the field of alloy processing technology. After alloying, grains with uniform grain size and an average grain size of less than 136μm are obtained. Such fine grains will increase the strengthening effect, improve the alloy strength and reduce the anisotropy of the high-strength aluminum-lithium alloy. After a series of heat treatments, higher strength and elongation can be obtained.

[0004] Chinese patent CN115418534B relates to an 8090 aluminum-lithium alloy fine-grained plate and its preparation method. By combining hot rolling, heat treatment, and cold rolling, the comprehensive performance of the aluminum-lithium alloy is improved. This effectively addresses the problems of coarse grains in the plate during the production of the 8090 aluminum-lithium alloy, as well as the uneven microstructure and mechanical properties after rolling. The aluminum-lithium alloy plate of this invention significantly refines the grains and improves the original fibrous microstructure, thereby resolving the uneven microstructure and mechanical properties after rolling and further improving the industrial application level of the 8090 aluminum-lithium alloy. The aluminum-lithium alloys prepared in the aforementioned two patents have uneven fine grain distribution and are prone to cracking during production. The present invention achieves a uniform distribution of precipitated phases and finer grains through particle reinforcement and hydrothermal reaction.

[0005] Adding nanoparticles to aluminum-lithium alloys can further increase the capacity of dislocations in the aluminum matrix, improve the nucleation rate during recasting, and refine the grains. At the same time, it can also make the precipitated phase more uniform and finer. In order to obtain a fine grain structure, reasonable thermomechanical treatment must be carried out before using aluminum-lithium alloys to manufacture parts. Although traditional thermomechanical treatment can produce plates with higher surface quality and meet the requirements of longitudinal mechanical properties through a simple "preheating + rolling" method, the traditional preheating and rolling method fails to break up the fibrous structure after rolling, nor does it promote the effective recrystallization. The final structure after rolling is fibrous, resulting in the structure and mechanical properties of the aluminum-lithium alloy plate showing obvious orientation. In response to this situation, the present invention combines the idea of ​​improving the heat treatment process from the perspective of changing the rolling process to achieve the purpose of particle-reinforced aluminum-lithium alloy. Summary of the Invention

[0006] To address the shortcomings of existing aluminum-lithium alloy materials, the present invention provides a processing technology for a nano-WC particle reinforced aluminum-lithium alloy composite material. WC particles and Ce elements are added to the aluminum-lithium alloy and a fine-grained structure is obtained by rolling and heat treatment. A cobalt source is added to the precursor and a hydrothermal reaction is performed. The specific operating steps are as follows:

[0007] (1) Mg blocks, Cu blocks, Mn blocks, Zn blocks, Ce blocks, and WC particles are placed in a ball mill and ground into powder, which is then pressed into cylindrical pieces.

[0008] (2) The cylindrical piece obtained in step (1) is heated, kept warm, cooled to room temperature, and polished to obtain a WC master alloy.

[0009] (3) After the WC intermediate alloy obtained in step (2) is melted, it is cooled and a pure Li block is added (the temperature must be lowered to prevent lithium explosion). After the lithium block is melted, electromagnetic stirring is performed. After the melt is fully stirred, it is cast and molded to obtain a WC aluminum-lithium alloy casting.

[0010] (4) The WC aluminum-lithium alloy casting obtained in step (3) is subjected to a two-stage homogenization treatment, and the process parameters are: first treating at 410° C. for 3 h, and then treating at 520° C. for 2 h.

[0011] (5) hot rolling the WC aluminum-lithium alloy casting processed in step (4) to obtain a WC aluminum-lithium alloy sheet.

[0012] (6) The WC aluminum-lithium alloy sheet obtained in step (5) was subjected to a solution treatment with the process parameters of 510° C. for 100 min and then water-cooled at 30° C.

[0013] (7) The WC aluminum-lithium alloy sheet treated in step (6) is subjected to cold rolling. Liquid nitrogen deep cooling is performed after each cold rolling. The deep liquid nitrogen treatment is to make the WC particles evenly distributed in the aluminum matrix to ensure that the T1 phase is evenly distributed and small in size.

[0014] (8) Adding a cobalt source to deionized water and dissolving it to form a precursor solution; hydrothermally reacting the WC aluminum-lithium alloy sheet treated in step (7) with the precursor solution.

[0015] (9) The WC aluminum-lithium alloy sheet treated in step (8) is artificially aged at 180° C. for 19 h to obtain a composite aluminum-lithium alloy material having a large amount of fine-grained microstructure and a heterogeneous structure.

[0016] Preferably, the WC aluminum-lithium alloy contains common alloying elements of 1.3% to 3% Li, 0.4% to 0.5% Mg, 0.4% to 1.6% Cu, 0.2% to 1.5% Mn, 1% to 1.5% Zn, 0.3% to 0.4% Ce, 30% nano WC particles, and the balance of Al and unavoidable impurities.

[0017] Preferably, the cylindrical shape in step (1) has a specification of 40 mm x 20 mm.

[0018] Preferably, the heating temperature in step (2) is 550° C., the heating time is 15 min, and the temperature is kept at 250° C. for 10 h.

[0019] Preferably, in step (3), the aluminum block is added after cooling to 700° C., the frequency of electromagnetic stirring is 35 Hz, the alternating current is 100 A, and the final casting specification is 50x50x25 mm.

[0020] Preferably, the water quenching time in step (4) should be kept within 15 s.

[0021] Preferably, the process parameters of the hot rolling treatment in step (5) are as follows: the temperature is set to 200°C, the pressing is performed 5 times, the time of each hot rolling should be kept within 30 minutes, and the sample is returned to the furnace and kept warm for 20 minutes after each hot rolling, the holding temperature is 147°C, and the total reduction rate is 80%.

[0022] Preferably, the process parameters of the cold rolling treatment in step (7) are as follows: the temperature is set to 20° C., the pressing is performed 4 times, and the total reduction rate is 40%.

[0023] Preferably, in step (8), the cobalt source is added in the form of a cobalt chloride solution in an amount of 0.03 g / L.

[0024] Preferably, the temperature of the hydrothermal reaction in step (9) is 200° C., the time is 12 h, and the pressure is 1 MPa.

[0025] Principle of the present invention:

[0026] The present invention adds a cobalt source to the precursor solution, forming a new coordination compound, CoAl2O4, with the surface of the aluminum-lithium alloy. This compound exhibits high strength, high corrosion resistance, and excellent electrical conductivity. Furthermore, the present invention performs a solution treatment on the material after adding the WC particles, enabling more uniform diffusion of the cobalt throughout the material and facilitating the uniform distribution of the T1 phase around the WC particles.

[0027] Aging is a common process for improving the performance of heat-treatable aluminum alloys. During the aging process, the primary precipitate in aluminum-lithium binary alloys is the metastable strengthening phase, δ' (Al3Li). Adding Cu produces two new precipitates: θ' (Al2Cu) and T1 (Al2CuLi). T1 is the primary strengthening phase in Al-Cu-Li alloys. Adding nano-WC particles can make the T1 phase more uniformly distributed and finer in size within the matrix.

[0028] Beneficial effects of the present invention

[0029] (1) The present invention increases the content of fine-grained structure in the material by adding a certain amount of nano-WC particles and adopting a deformation method combining cold rolling and hot rolling. At the same time, the content of precipitated phase in the material is increased by two-stage homogenization treatment and two solid solution treatments, thereby obtaining a fine-grained aluminum-lithium alloy with high corrosion resistance.

[0030] (2) After cold rolling, deep liquid nitrogen treatment can make the WC particles evenly distributed in the aluminum matrix, ensuring that the T1 phase is evenly distributed and small in size.

[0031] (3) A cobalt source is added to the precursor solution, and a new coordination compound CoAl2O4 is formed with the aluminum matrix under hydrothermal reaction. This compound has high strength and good corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the heat treatment flow chart.

[0033] Figure 2 It is a process flow chart. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0035] Example 1

[0036] The chemical composition of the nano WC particle reinforced aluminum-lithium alloy in this embodiment is shown in Table 1.

[0037] Table 1 Chemical composition of nano WC particle reinforced aluminum-lithium alloy in Example 1

[0038]

[0039] The specific preparation steps are as follows:

[0040] (1) According to the contents shown in Table 1, Mg blocks, Cu blocks, Mn blocks, Zn blocks, Ce blocks, WC particles, Al blocks and inevitable impurities were placed in a ball mill and ground into powder, which was then pressed into cylindrical pieces of 40 mm x 20 mm.

[0041] (2) The cylindrical piece obtained in step (1) was placed in a combustion reactor, heated at 550°C for 15 minutes, and kept at 250°C for 10 hours. The piece was cooled to room temperature and polished to obtain a WC master alloy.

[0042] (3) The WC master alloy obtained in step (2) was melted and cooled to 700°C, pure lithium blocks were added, and the mixture was placed in an electromagnetic stirrer for stirring. The frequency was set to 35 Hz and the alternating current was set to 100 A. After the melt was fully stirred, it was cast into a casting of 50 x 50 x 25 mm.

[0043] (4) The WC aluminum-lithium alloy casting obtained in step (3) was heated to 410° C., kept at this temperature for 1 hour, air-cooled for 1 hour, then heated to 520° C., kept at this temperature for 3 hours, and water-quenched for 14 seconds.

[0044] (5) The WC aluminum-lithium alloy casting treated in step (4) was hot rolled. The sample was heated to 200° C. and rolled with a total reduction rate of 80%. The rolling was carried out in 5 steps. After each hot rolling, the sample was returned to the furnace and kept warm for 20 minutes at a holding temperature of 147° C. to obtain a WC aluminum-lithium alloy sheet.

[0045] (6) The WC aluminum-lithium alloy sheet obtained in step (5) was heated to 510° C., kept warm for 100 min, and water quenched for 14 s to obtain a heat-treated sample with a primary precipitated phase.

[0046] (7) The WC aluminum-lithium alloy sheet treated in step (6) is cold rolled by cyclic rolling. The original thickness is 5 mm, and the reduction amount each time is gradually reduced to 1 mm, 0.5 mm, 0.3 mm, and 0.2 mm, respectively. The final plate thickness is 3 mm, the total reduction amount is 2 mm, and the total reduction rate is 40%. After each cold rolling, the sample is deep-cold treated with liquid nitrogen to obtain a WC aluminum-lithium alloy sheet with a large amount of fine grain structure.

[0047] (8) Cobalt chloride is added to deionized water to form a precursor solution, wherein the content of cobalt chloride in the solution is 0.03 g / L, and the WC aluminum-lithium alloy sheet treated in step (7) is subjected to a hydrothermal reaction with the precursor solution. The hydrothermal reaction conditions are a temperature of 200° C., a time of 12 h, and a pressure of 1 MPa to obtain a heterogeneous structure.

[0048] (9) The WC aluminum-lithium alloy sheet treated in step (8) is heated to 180° C. and kept warm for 19 hours to finally obtain a composite aluminum-lithium alloy material having a large amount of fine-grained structure and heterogeneous structure.

[0049] The tensile strength of the composite aluminum-lithium alloy material prepared in this embodiment was measured to be 560 MPa, and the elongation was 9.5%.

[0050] Example 2

[0051] The chemical composition of the nano WC particle reinforced aluminum-lithium alloy in this embodiment is shown in Table 2.

[0052] Table 2 Chemical composition of nano WC particle reinforced aluminum-lithium alloy in Example 2

[0053]

[0054] The specific preparation steps are as follows:

[0055] (1) According to the contents shown in Table 1, Mg blocks, Cu blocks, Mn blocks, Zn blocks, Ce blocks, WC particles, Al blocks and inevitable impurities were placed in a ball mill and ground into powder, which was then pressed into cylindrical pieces of 40 mm x 20 mm.

[0056] (2) The cylindrical piece obtained in step (1) was placed in a combustion reactor, heated at 550°C for 15 minutes, and kept at 250°C for 10 hours. The piece was cooled to room temperature and polished to obtain a WC master alloy.

[0057] (3) The WC master alloy obtained in step (2) was melted and cooled to 700°C, pure lithium blocks were added, and the mixture was placed in an electromagnetic stirrer for stirring. The frequency was set to 35 Hz and the alternating current was set to 100 A. After the melt was fully stirred, it was cast into a WC aluminum-lithium alloy casting of 50 x 50 x 25 mm.

[0058] (4) The WC aluminum-lithium alloy casting obtained in step (3) was heated to 410° C., kept at this temperature for 1 hour, air-cooled for 1.5 hours, then heated to 520° C., kept at this temperature for 3 hours, and water-quenched for 13 seconds.

[0059] (5) The WC aluminum-lithium alloy casting treated in step (4) was hot rolled. The sample was heated to 200°C and rolled with a total reduction rate of 80%. The rolling was carried out in 5 steps, and the reduction amount gradually decreased. The first step was 8 mm, the second step was 6 mm, the third step was 3 mm, the fourth step was 2 mm, and the fifth step was 1 mm. After each hot rolling, the sample was returned to the furnace and kept warm for 20 minutes at a holding temperature of 147°C.

[0060] (6) The WC aluminum-lithium alloy sheet obtained in step (5) was heated to 510° C., kept warm for 100 min, and water quenched for 13 s to obtain a heat-treated sample with a primary precipitated phase.

[0061] (7) The WC aluminum-lithium alloy sheet treated in step (6) was cold rolled, with an original thickness of 5 mm. The reduction amount was gradually reduced to 1 mm, 0.5 mm, 0.3 mm, and 0.2 mm, respectively. The final sheet thickness was 3 mm, the total reduction amount was 2 mm, and the total reduction rate was 40%. After each cold rolling, the sample was deep-cold treated with liquid nitrogen to obtain a WC aluminum-lithium alloy sheet with a large amount of fine grain structure.

[0062] (8) Cobalt chloride is added to deionized water to form a precursor solution, ensuring that the content of cobalt chloride in the solution is 0.03 g / L, and the WC aluminum-lithium alloy sheet treated in step (7) is hydrothermally reacted with the precursor solution. The conditions of the hydrothermal reaction are temperature of 200° C., time of 12 h, and pressure of 1 MPa to obtain a heterogeneous structure.

[0063] (9) The WC aluminum-lithium alloy sheet treated in step (8) is heated to 180° C. and kept warm for 19 hours to finally obtain a composite aluminum-lithium alloy material having a large amount of fine-grained structure and heterogeneous structure.

[0064] The composite aluminum-lithium alloy material prepared in this embodiment has been measured to have a tensile strength of 550 MPa and an elongation of 9%.

[0065] Example 3

[0066] The chemical composition of the nano WC particle reinforced aluminum-lithium alloy in this embodiment is shown in Table 3.

[0067] Table 3 Chemical composition of nano WC particle reinforced aluminum-lithium alloy in Example 3

[0068]

[0069] The specific preparation steps are as follows:

[0070] (1) According to the contents shown in Table 1, Mg blocks, Cu blocks, Mn blocks, Zn blocks, Ce blocks, WC particles, Al blocks and inevitable impurities were placed in a ball mill and ground into powder, which was then pressed into cylindrical pieces of 40 mm x 20 mm.

[0071] (2) The cylindrical piece obtained in step (1) was placed in a combustion reactor, heated at 550°C for 15 minutes, and kept at 250°C for 10 hours. The piece was cooled to room temperature and polished to obtain a WC master alloy.

[0072] (3) The WC master alloy obtained in step (2) was melted and cooled to 700°C, pure lithium blocks were added, and the mixture was placed in an electromagnetic stirrer for stirring. The frequency was set to 35 Hz and the alternating current was set to 100 A. After the melt was fully stirred, it was cast into a WC aluminum-lithium alloy casting of 50 x 50 x 25 mm.

[0073] (4) The WC aluminum-lithium alloy casting obtained in step (3) was heated to 410° C., kept at this temperature for 2 h, air-cooled for 2 h, then heated to 520° C., kept at this temperature for 3 h, and water-quenched for 10 s.

[0074] (5) The WC aluminum-lithium alloy casting treated in step (4) was hot rolled. The sample was heated to 200°C and rolled with a total reduction rate of 80%. The rolling was carried out in 5 steps, and the reduction amount was gradually reduced. The first step was 8 mm, the second step was 6 mm, the third step was 3 mm, the fourth step was 2 mm, and the fifth step was 1 mm. After each hot rolling, the sample was returned to the furnace and kept warm for 20 minutes at a holding temperature of 147°C to obtain a WC aluminum-lithium alloy sheet.

[0075] (6) The WC aluminum-lithium alloy sheet obtained in step (5) was heated to 510° C., kept warm for 100 min, and water quenched for 10 s to obtain a heat-treated sample with a primary precipitated phase.

[0076] (7) The WC aluminum-lithium alloy sheet treated in step (6) was cold rolled, with an original thickness of 5 mm. The reduction amount was gradually reduced to 1 mm, 0.5 mm, 0.3 mm, and 0.2 mm, respectively. The final sheet thickness was 3 mm, the total reduction amount was 2 mm, and the total reduction rate was 40%. After each cold rolling, the sample was deep-cold treated with liquid nitrogen to obtain a WC aluminum-lithium alloy sheet with a large amount of fine grain structure.

[0077] (8) Cobalt chloride is added to deionized water to form a precursor solution, ensuring that the content of cobalt chloride in the solution is 0.03 g / L, and the WC aluminum-lithium alloy sheet treated in step (7) is hydrothermally reacted with the precursor solution. The hydrothermal reaction conditions are 200° C., time 12 h, and pressure 1 MPa to obtain a heterogeneous structure.

[0078] (9) The WC aluminum-lithium alloy sheet treated in step (8) is heated to 180° C. and kept warm for 19 hours to finally obtain a composite aluminum-lithium alloy material having a large amount of fine-grained structure and heterogeneous structure.

[0079] The composite aluminum-lithium alloy material prepared in this embodiment has been measured to have a tensile strength of 540 MPa and an elongation of 8.5%.

[0080] Comparative Example 1

[0081] For comparison, the difference between this embodiment and embodiment 1 is that the bipolar homogenization process is changed to a homogenization process. The specific preparation steps are as follows:

[0082] (1) According to the contents shown in Table 1, Mg blocks, Cu blocks, Mn blocks, Zn blocks, Ce blocks, WC particles, Al blocks and inevitable impurities were placed in a ball mill and ground into powder, which was then pressed into cylindrical pieces of 40 mm x 20 mm.

[0083] (2) The cylindrical piece obtained in step (1) was placed in a combustion reactor, heated at 550°C for 15 minutes, and kept at 250°C for 10 hours. The piece was cooled to room temperature and polished to obtain a WC master alloy.

[0084] (3) The WC master alloy obtained in step (2) was melted and cooled to 700°C, pure lithium blocks were added, and the mixture was placed in an electromagnetic stirrer for stirring. The frequency was set to 35 Hz and the alternating current was set to 100 A. After the melt was fully stirred, it was cast into a WC aluminum-lithium alloy casting of 50 x 50 x 25 mm.

[0085] (4) The WC aluminum-lithium alloy casting obtained in step (3) was heated to 410° C., kept at this temperature for 1 hour, and air-cooled for 1 hour.

[0086] (5) The WC aluminum-lithium alloy casting treated in step (4) was hot rolled. The sample was heated to 200° C. and rolled with a total reduction rate of 80%. The rolling was carried out in 5 steps, with a reduction of 4 mm each time. After each hot rolling, the sample was returned to the furnace and kept warm for 20 minutes at a holding temperature of 147° C. to obtain a WC aluminum-lithium alloy sheet.

[0087] (6) The WC aluminum-lithium alloy sheet obtained in step (5) was heated to 510° C., kept warm for 100 min, and water quenched for 14 s to obtain a heat-treated sample with a primary precipitated phase.

[0088] (7) The WC aluminum-lithium alloy sheet treated in step (6) was cold rolled, with an original thickness of 5 mm. The reduction amount was gradually reduced to 1 mm, 0.5 mm, 0.3 mm, and 0.2 mm, respectively. The final sheet thickness was 3 mm, the total reduction amount was 2 mm, and the total reduction rate was 40%. After each cold rolling, the sample was deep-cold treated with liquid nitrogen to obtain a WC aluminum-lithium alloy sheet with a large amount of fine grain structure.

[0089] (8) Adding cobalt chloride to deionized water to form a precursor solution, ensuring that the content of cobalt chloride in the solution is 0.003 g / L, and subjecting the WC aluminum-lithium alloy sheet treated in step (7) to a hydrothermal reaction with the precursor solution. The conditions of the hydrothermal reaction are a temperature of 200° C., a time of 12 h, and a pressure of 1 MPa to obtain a heterogeneous structure.

[0090] (9) The WC aluminum-lithium alloy sheet treated in step (8) is heated to 180° C. and kept warm for 19 hours to finally obtain a composite aluminum-lithium alloy material having a large amount of fine-grained structure and heterogeneous structure.

[0091] The composite aluminum-lithium alloy material prepared in this embodiment has been measured to have a tensile strength of 530 MPa and an elongation of 8%.

[0092] Compared with Example 1, Comparative Example 1 changed the double-stage homogenization treatment to a homogenization treatment. As a result, the tensile strength and elongation of the material decreased. The reason is that the double-stage homogenization treatment is beneficial to the uniform distribution of WC particles in the material, which proves that the double-stage homogenization treatment helps to improve the strength and toughness of the material.

[0093] Comparative Example 2

[0094] As a comparison, this example differs from Example 1 in that no nano WC particles are added. The chemical composition of the aluminum-lithium alloy in this comparative example is shown in Table 4, and the specific preparation steps are the same as those in Example 1.

[0095] Table 4 Chemical composition of the aluminum-lithium alloy in Comparative Example 2

[0096]

[0097] The specific preparation steps are as follows:

[0098] (1) According to the contents shown in Table 1, Mg blocks, Cu blocks, Mn blocks, Zn blocks, Ce blocks, Al blocks and inevitable impurities were placed in a ball mill and ground into powder, which was then pressed into cylindrical pieces of 40 mm x 20 mm.

[0099] (2) The cylindrical piece obtained in step (1) was placed in a combustion reactor, heated at 550°C for 15 minutes, and kept at 250°C for 10 hours. The piece was cooled to room temperature and polished to obtain an intermediate alloy.

[0100] (3) The intermediate alloy obtained in step (2) was melted and cooled to 700°C, pure lithium blocks were added, and the mixture was placed in an electromagnetic stirrer for stirring. The frequency was set to 35 Hz and the alternating current was set to 100 A. After the melt was fully stirred, it was cast into a 50x50x25 mm aluminum-lithium alloy casting.

[0101] (4) The aluminum-lithium alloy casting obtained in step (3) was heated to 410° C., kept at this temperature for 1 hour, air-cooled for 1 hour, then heated to 520° C., kept at this temperature for 3 hours, and water-quenched for 14 seconds.

[0102] (5) The aluminum-lithium alloy casting treated in step (4) was hot-rolled. The sample was heated to 440° C. and rolled with a total reduction rate of 80%. The rolling was carried out in 5 steps, with a reduction of 4 mm each time. After each hot rolling, the sample was returned to the furnace and kept warm for 20 minutes at a holding temperature of 147° C. to obtain an aluminum-lithium alloy sheet.

[0103] (6) The aluminum-lithium alloy sheet obtained in step (5) was heated to 510° C., kept warm for 100 min, and water quenched for 14 s to obtain a heat-treated sample with a primary precipitated phase.

[0104] (7) The aluminum-lithium alloy sheet treated in step (6) is cold-rolled by cyclic rolling. The original thickness is 5 mm, and the reduction amount each time is gradually reduced to 1 mm, 0.5 mm, 0.3 mm, and 0.2 mm, respectively. The final plate thickness is 3 mm, the total reduction amount is 2 mm, and the total reduction rate is 40%. After each cold rolling, the sample is deep-cold treated with liquid nitrogen to obtain a WC aluminum-lithium alloy sheet with a large amount of fine grain structure.

[0105] (8) Adding cobalt chloride in an amount of 0.03 g / L to deionized water to form a precursor solution, and subjecting the aluminum-lithium alloy sheet treated in step (7) to a hydrothermal reaction with the precursor solution. The hydrothermal reaction conditions are 200° C., 12 h, and 1 MPa to obtain a heterogeneous structure.

[0106] (9) The aluminum-lithium alloy sheet treated in step (8) is heated to 180° C. and kept warm for 19 hours to finally obtain a composite aluminum-lithium alloy material having a large amount of fine-grained microstructure and heterogeneous structure.

[0107] The composite aluminum-lithium alloy material prepared in this embodiment has been measured to have a tensile strength of 460 MPa and an elongation of 8%.

[0108] Compared to Example 1, which lacks the addition of nano-WC particles, the tensile strength and elongation of the alloy decrease significantly, demonstrating that the addition of nano-WC particles can significantly improve the toughness of the aluminum-lithium alloy. This is because the nano-WC particles promote the precipitation of the T1 phase in the aluminum-lithium alloy and also ensure its uniform distribution within the aluminum matrix.

[0109] Comparative Example 3

[0110] For comparison, the difference between this embodiment and embodiment 1 is that no cobalt source is added to the precursor solution. The specific preparation steps are as follows:

[0111] (1) According to the contents shown in Table 1, Mg blocks, Cu blocks, Mn blocks, Zn blocks, Ce blocks, WC particles, Al blocks and inevitable impurities were placed in a ball mill and ground into powder, which was then pressed into cylindrical pieces of 40 mm x 20 mm.

[0112] (2) The cylindrical piece obtained in step (1) was placed in a combustion reactor, heated at 550°C for 15 minutes, and kept at 250°C for 10 hours. The piece was cooled to room temperature and polished to obtain a WC master alloy.

[0113] (3) The WC master alloy obtained in step (2) was melted and cooled to 700°C, pure lithium blocks were added, and the mixture was placed in an electromagnetic stirrer for stirring. The frequency was set to 35 Hz and the alternating current was set to 100 A. After the melt was fully stirred, it was cast into a WC aluminum-lithium alloy casting of 50 x 50 x 25 mm.

[0114] (4) The WC aluminum-lithium alloy casting obtained in step (3) was heated to 410° C., kept at this temperature for 1 hour, air-cooled for 1 hour, then heated to 520° C., kept at this temperature for 3 hours, and water-quenched for 14 seconds.

[0115] (5) The WC aluminum-lithium alloy casting treated in step (4) was hot rolled. The sample was heated to 200° C. and rolled with a total reduction rate of 80%. The rolling was carried out in 5 steps, with a reduction of 4 mm each time. After each hot rolling, the sample was returned to the furnace and kept warm for 20 minutes at a holding temperature of 147° C. to obtain a WC aluminum-lithium alloy sheet.

[0116] (6) The WC aluminum-lithium alloy sheet obtained in step (5) was heated to 510° C., kept warm for 100 min, and water quenched for 14 s to obtain a heat-treated sample with a primary precipitated phase.

[0117] (7) The WC aluminum-lithium alloy sheet treated in step (6) is cold rolled by cyclic rolling. The original thickness is 5 mm, and the reduction amount each time is gradually reduced to 1 mm, 0.5 mm, 0.3 mm, and 0.2 mm, respectively. The final plate thickness is 3 mm, the total reduction amount is 2 mm, and the total reduction rate is 40%. After each cold rolling, the sample is deep-cold treated with liquid nitrogen to obtain a WC aluminum-lithium alloy sheet with a large amount of fine grain structure.

[0118] (8) The WC aluminum-lithium alloy sheet treated in step (7) was subjected to a hydrothermal reaction at 200° C., for 12 h, and at a pressure of 1 MPa.

[0119] (9) The WC aluminum-lithium alloy sheet treated in step (8) is heated to 180° C. and kept warm for 19 hours to finally obtain a composite aluminum-lithium alloy material having a large amount of fine-grained structure and heterogeneous structure.

[0120] The composite aluminum-lithium alloy material prepared in this embodiment has been measured to have a tensile strength of 542 MPa and an elongation of 8.5%.

[0121] Compared with Example 1, this comparative example does not add a cobalt source, and its mechanical properties are not as good as Example 1. The reason is that cobalt and aluminum form a new coordination compound, which has high strength and good corrosion resistance. Adhering to the alloy surface can improve the tensile strength and corrosion resistance of the material to a certain extent.

[0122] Comparative Example 4

[0123] As a comparison, this embodiment differs from embodiment 1 in that no cryogenic liquid nitrogen treatment is performed after each cold rolling. The specific preparation steps are as follows:

[0124] (1) According to the contents shown in Table 1, Mg blocks, Cu blocks, Mn blocks, Zn blocks, Ce blocks, WC particles, Al blocks and inevitable impurities were placed in a ball mill and ground into powder, which was then pressed into cylindrical pieces of 40 mm x 20 mm.

[0125] (2) The cylindrical piece obtained in step (1) was placed in a combustion reactor, heated at 550°C for 15 minutes, and kept at 250°C for 10 hours. The piece was cooled to room temperature and polished to obtain a WC master alloy.

[0126] (3) The WC master alloy obtained in step (2) was melted and cooled to 700°C, pure lithium blocks were added, and the mixture was placed in an electromagnetic stirrer for stirring. The frequency was set to 35 Hz and the alternating current was set to 100 A. After the melt was fully stirred, it was cast into a WC aluminum-lithium alloy casting of 50 x 50 x 25 mm.

[0127] (4) The WC aluminum-lithium alloy casting obtained in step (3) was heated to 410° C., kept at this temperature for 1 hour, air-cooled for 1 hour, then heated to 520° C., kept at this temperature for 3 hours, and water-quenched for 14 seconds.

[0128] (5) The WC aluminum-lithium alloy casting treated in step (4) was hot rolled. The sample was heated to 200° C. and rolled with a total reduction rate of 80%. The rolling was carried out in 5 steps, with a reduction of 4 mm each time. After each hot rolling, the sample was returned to the furnace and kept warm for 20 minutes at a holding temperature of 147° C. to obtain a WC aluminum-lithium alloy sheet.

[0129] (6) The WC aluminum-lithium alloy sheet obtained in step (5) was heated to 510° C., kept warm for 100 min, and water quenched for 14 s to obtain a heat-treated sample with a primary precipitated phase.

[0130] (7) The WC aluminum-lithium alloy sheet processed in step (6) is cold-rolled, with an original thickness of 5 mm and a reduction amount decreasing step by step to 1 mm, 0.5 mm, 0.3 mm, and 0.2 mm, respectively. The final sheet thickness is 3 mm, the total reduction amount is 2 mm, and the total reduction rate is 40%, thereby obtaining a WC aluminum-lithium alloy sheet.

[0131] (8) Adding cobalt chloride to deionized water to form a precursor solution, ensuring that the content of cobalt chloride in the solution is 0.003 g / L, and subjecting the WC aluminum-lithium alloy sheet treated in step (7) to a hydrothermal reaction with the precursor solution. The hydrothermal reaction conditions are 200° C., 12 h, and 1 MPa to obtain a heterogeneous structure.

[0132] (9) The WC aluminum-lithium alloy sheet treated in step (8) is heated to 180° C. and kept warm for 19 hours to finally obtain a composite aluminum-lithium alloy material having a large amount of fine-grained structure and heterogeneous structure.

[0133] The composite aluminum-lithium alloy material prepared in this embodiment has been measured to have a tensile strength of 520 MPa and an elongation of 8.1%.

[0134] The mechanical properties of this comparative example are not as good as those of Example 1. The reason is that the residual internal stress in the material is eliminated and its plastic toughness is improved through deep-cold liquid nitrogen treatment.

[0135] Comparative Example 5

[0136] For comparison, the difference between this embodiment and embodiment 1 is that cold rolling is first performed after hot rolling, and then solution treatment is performed. The specific preparation steps are as follows:

[0137] (1) According to the contents shown in Table 1, Mg blocks, Cu blocks, Mn blocks, Zn blocks, Ce blocks, WC particles, Al blocks and inevitable impurities were placed in a ball mill and ground into powder, which was then pressed into cylindrical pieces of 40 mm x 20 mm.

[0138] (2) The cylindrical piece obtained in step (1) was placed in a combustion reactor, heated at 550°C for 15 minutes, and kept at 250°C for 10 hours. The piece was cooled to room temperature and polished to obtain a WC master alloy.

[0139] (3) The WC master alloy obtained in step (2) was melted and cooled to 700°C, pure lithium blocks were added, and the mixture was placed in an electromagnetic stirrer for stirring. The frequency was set to 35 Hz and the alternating current was set to 100 A. After the melt was fully stirred, it was cast into a WC aluminum-lithium alloy casting of 50 x 50 x 25 mm.

[0140] (4) The WC aluminum-lithium alloy casting obtained in step (3) was heated to 410° C., kept at this temperature for 1 hour, air-cooled for 1 hour, then heated to 520° C., kept at this temperature for 3 hours, and water-quenched for 14 seconds.

[0141] (5) The WC aluminum-lithium alloy casting treated in step (4) was hot rolled. The sample was heated to 200° C. and rolled with a total reduction rate of 80%. The rolling was carried out in 5 steps, with a reduction of 4 mm each time. After each hot rolling, the sample was returned to the furnace and kept warm for 20 minutes at a holding temperature of 147° C. to obtain a WC aluminum-lithium alloy sheet.

[0142] (6) The WC aluminum-lithium alloy sheet treated in step (5) was cold rolled, with an original thickness of 5 mm. The reduction amount was gradually reduced to 1 mm, 0.5 mm, 0.3 mm, and 0.2 mm, respectively. The final sheet thickness was 3 mm, the total reduction amount was 2 mm, and the total reduction rate was 40%. After each cold rolling, the sample was deep-cold treated with liquid nitrogen to obtain a WC aluminum-lithium alloy sheet with a large amount of fine grain structure.

[0143] (7) The WC aluminum-lithium alloy sheet obtained in step (6) was heated to 510° C., kept warm for 100 min, and water quenched for 14 s to obtain a heat-treated sample with a primary precipitated phase.

[0144] (8) Adding cobalt chloride to deionized water to form a precursor solution, ensuring that the content of cobalt chloride in the solution is 0.003 g / L, and subjecting the WC aluminum-lithium alloy sheet treated in step (7) to a hydrothermal reaction with the precursor solution. The hydrothermal reaction conditions are a temperature of 200° C., a time of 12 h, and a pressure of 1 MPa to obtain a heterogeneous structure.

[0145] (9) The WC aluminum-lithium alloy sheet treated in step (8) is heated to 180° C. and kept warm for 19 hours to finally obtain a composite aluminum-lithium alloy material having a large amount of fine-grained structure and heterogeneous structure.

[0146] The composite aluminum-lithium alloy material prepared in this embodiment has been measured to have a tensile strength of 515 MPa and an elongation of 8.6%.

[0147] Compared with Example 1, the mechanical properties of this comparative example are not as good as those of Example 1. The reason is that after cold rolling, the solid solution treatment is performed, and the alloy elements are not well mixed with the solute atoms. At the same time, the grain structure that was originally refined by cold rolling becomes coarser again through the solid solution treatment.

Claims

1. A processing technology for a nano-WC particle reinforced aluminum-lithium alloy composite material, characterized by: WC particles are added to the aluminum-lithium alloy, and rolling and heat treatment are used to obtain a fine-grained structure. A cobalt source is added to the precursor and a hydrothermal reaction is carried out. The specific operation steps are as follows: (1) Mg blocks, Cu blocks, Mn blocks, Zn blocks, Ce blocks, WC particles, Al blocks and inevitable impurities are placed in a ball mill and ground into powder, which is then pressed into cylindrical pieces; (2) heating the cylindrical piece obtained in step (1), cooling it to room temperature after keeping it warm, and polishing it to obtain a WC master alloy; (3) The WC master alloy obtained in step (2) is melted, cooled, and then pure Li blocks are added. After the lithium blocks are melted, electromagnetic stirring is performed. After the melt is fully stirred, it is cast into a mold to obtain a WC aluminum-lithium alloy casting; (4) The WC aluminum-lithium alloy casting obtained in step (3) is subjected to a two-stage homogenization treatment, and the process parameters are: first, treatment at 410°C for 3 hours, air cooling for more than 1 hour, then treatment at 520°C for 2 hours, and water quenching; (5) hot rolling the WC aluminum-lithium alloy casting processed in step (4) to obtain a WC aluminum-lithium alloy sheet; (6) The WC aluminum-lithium alloy sheet obtained in step (5) was subjected to solution treatment at 510°C for 100 min, followed by water quenching at 30°C; (7) cold rolling the WC aluminum-lithium alloy sheet processed in step (6), and performing liquid nitrogen deep cooling after each cold rolling; (8) adding a cobalt source to deionized water and dissolving it to form a precursor solution; subjecting the WC aluminum-lithium alloy sheet treated in step (7) to a hydrothermal reaction with the precursor solution; (9) The WC aluminum-lithium alloy sheet treated in step (8) was artificially aged at 180° C. for 19 h to obtain a composite aluminum-lithium alloy material having a large amount of fine-grained microstructure and a heterogeneous structure.

2. The processing technology of the nano WC particle reinforced aluminum-lithium alloy composite material according to claim 1 is characterized in that: The WC aluminum-lithium alloy contains alloying elements of 1.3% to 3% Li, 0.4% to 0.5% Mg, 0.4% to 1.6% Cu, 0.2% to 1.5% Mn, 1% to 1.5% Zn, 0.3% to 0.4% Ce, 30% nano WC particles, and the balance of Al and unavoidable impurities.

3. The processing technology of the nano WC particle reinforced aluminum-lithium alloy composite material according to claim 1 is characterized in that: The cylindrical size in step (1) is 40 mm x 20 mm.

4. The processing technology of the nano WC particle reinforced aluminum-lithium alloy composite material according to claim 1 is characterized in that: In step (2), the heating temperature is 550°C for 15 minutes and the temperature is kept at 250°C for 10 hours.

5. The processing technology of the nano WC particle reinforced aluminum-lithium alloy composite material according to claim 1 is characterized in that: In step (3), the mixture was cooled to 700°C and Li blocks were added. The frequency of electromagnetic stirring was 35 Hz and the alternating current was 100 A. The final casting size was 50 x 50 x 25 mm.

6. The processing technology of the nano WC particle reinforced aluminum-lithium alloy composite material according to claim 1, characterized in that: The process parameters of the hot rolling treatment in step (5) are as follows: the temperature is set to 200°C, the pressing is performed 5 times, the time of each hot rolling should be kept within 30 minutes, and the sample is returned to the furnace and kept warm for 20 minutes after each hot rolling. The holding temperature is 147°C, and the total reduction rate is 80%.

7. The processing technology of the nano WC particle reinforced aluminum-lithium alloy composite material according to claim 1, characterized in that: The process parameters of the cold rolling treatment in step (7) are as follows: the temperature is set to 20°C, the pressing is performed 4 times, and the total pressing reduction is 40%.

8. The processing technology of the nano WC particle reinforced aluminum-lithium alloy composite material according to claim 1, characterized in that: In step (8), the cobalt source is cobalt chloride, and the amount added is 0.03 g / L.

9. The processing technology of the nano WC particle reinforced aluminum-lithium alloy composite material according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step (8) is 200°C, the time is 12 h, and the pressure is 1 MPa.

10. The processing technology of the nano WC particle reinforced aluminum-lithium alloy composite material according to claim 1, characterized in that: The water quenching time in all steps should be kept within 15 s.

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