A process for achieving strengthening and toughening of aluminum alloys by regulating solute atomic clusters in aluminum alloys

Abstract

This invention discloses a process for strengthening and toughening aluminum alloys by controlling the atomic clusters of solutes, belonging to the technical field of aluminum alloy strengthening and toughening production processes. The aluminum alloy described in this invention contains, by mass percentage, 10%–12% Si, 1%–1.5% Mg, 3%–6% Cu, 2%–2.6% Zr, 2%–3% Ni, Al, and unavoidable impurities. The process for strengthening and toughening aluminum alloys by controlling the atomic clusters of solutes includes induction furnace melting of the aluminum alloy, laser-promoted cluster formation combined with DC current cluster ionization, and pulsed magnetic field casting. The final product is an aluminum alloy ingot with an Al-Si cluster particle size of 20 μm, clusters accounting for 20% of the primary crystals, and the primary Al and Si crystals exhibiting fine-grained spherical equiaxed crystals. The difference between the center and edge of the ingot is within 1.5%, achieving the goal of strengthening and toughening the aluminum alloy.

Description

Technical Field

[0001] This invention relates to a process for strengthening and toughening aluminum alloys by regulating the atomic clusters of aluminum alloy solutes, belonging to the technical field of aluminum alloy strengthening and toughening production processes. Background Technology

[0002] Thanks to the development of advanced characterization techniques such as analog-to-parameter (APT) and scanning transmission electron microscopy (STEM), the strengthening of metal solute atomic clusters has gradually come into the researchers' view. Studying the mechanism of cluster strengthening and regulating solute atomic cluster strengthening to improve the mechanical properties of aluminum alloys are currently research challenges and key areas. Since magnetic fields can lower the cluster formation energy and alter melt flow characteristics, creating energy and structural fluctuations in cluster formation, they are widely used in the cluster strengthening and toughening process of aluminum alloys.

[0003] Invention patent CN111155041B describes a method for strengthening and toughening regenerated deformed aluminum alloys. This method involves applying alternating stress along the deformation direction in a cyclic tensile-compression process, driving dislocation movement to precipitate a second phase and achieve strengthening. While this method can control atomic vacancy clusters by regulating dislocation movement, the large deformation treatment leads to work hardening and decreased toughness in the aluminum alloy. Furthermore, the manufacturing process is complex, and the cyclic hot-cold treatment and tensile-compression deformation reduce the fatigue strength of the aluminum alloy.

[0004] Invention patent CN113061820B describes a method for strengthening and toughening ZL205A aluminum alloy, which involves strengthening the alloy through multiple cold rolling and recrystallization annealing followed by solution treatment. While this method is simple, it cannot effectively control grain distribution, and due to limitations in solution treatment temperature, the solubility is limited at low temperatures, resulting in a less pronounced strengthening effect.

[0005] Invention patent CN108796313B describes an Al-Mg-Si wrought aluminum alloy and its strengthening and toughening treatment method, which improves the hardness of the aluminum alloy through microwave solution treatment and cryogenic treatment. However, this method involves complex processing conditions, requiring liquid nitrogen cryogenic treatment, making the process extremely difficult.

[0006] In summary, current aluminum alloy processing methods largely focus on deformation strengthening and solution treatment combined with aging. This invention considers the solute atom clusters in aluminum alloys, utilizing the high specific surface area and high thermal stability of these clusters to propose cluster strengthening. The small size and high specific surface area of ​​the clusters can effectively hinder dislocation slip, while the high interfacial energy can improve the material's compressive strength, forming a buffer layer. Compared to other strengthening methods, the nanoscale size of the clusters can also influence grain refinement. Regarding the control of solute atom cluster formation, unlike other methods that regulate cluster formation through temperature, this invention proposes a method that regulates cluster formation through a magnetic field. Starting from the origin of the clusters, the magnetic field lowers the energy barrier for vacancy migration, increasing the vacancy concentration to induce cluster formation. This method is simple, low-cost, and can effectively control the size and concentration area of ​​the clusters. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a process for strengthening and toughening aluminum alloys by controlling the atomic clusters of aluminum alloy solutes. The specific processing steps for strengthening and toughening aluminum alloys using a combination of cluster ionization and pulsed magnetic field treatment, as well as asynchronous magnetic field and casting processes, are as follows:

[0008] (1) Aluminum alloy melt is obtained by melting Si, Mg, Cu, Zr, Ni, Al and unavoidable impurities.

[0009] (2) The aluminum alloy melt obtained in step (1) is subjected to laser irradiation treatment by laser evaporation equipment, and nano-level clusters are formed in the melt after treatment.

[0010] (3) The aluminum alloy melt treated in step (2) is passed through a direct current.

[0011] (4) The aluminum alloy melt treated in step (3) is placed in a continuous cooling casting machine and a pulsed magnetic field is introduced to obtain aluminum alloy rods. The opening of the pulsed magnetic field is asynchronous with the casting process. The uniform distribution of clusters is controlled by the pulsed magnetic field, and the uniformity of grain size at the edge and core of the ingot is controlled by the asynchronous operation of the pulsed magnetic field and casting.

[0012] (5) The aluminum alloy rods treated in step (4) are water quenched.

[0013] Preferably, in step (1), the total mass percentage of Si, Mg, Cu, Zr, Ni, Al and unavoidable impurities is 100%, which includes 10% to 12% Si, 1% to 1.5% Mg, 3% to 6% Cu, 2% to 2.6% Zr, 2% to 3% Ni, and the balance is Al and unavoidable impurities.

[0014] Preferably, the melting temperature in step (1) is 650-750℃.

[0015] Preferably, in step (2), the laser power is controlled at 30-50W and the irradiation time is 30-50s.

[0016] Preferably, in step (3), the DC voltage is controlled at 10-30V, the current at 10-20μA, the temperature of the ionization process should be 500℃ lower than the nucleation temperature, and the ionization is more complete when the temperature is controlled at 440-480℃, and the reaction time is controlled at 30-50ms.

[0017] Preferably, in step (4), casting is performed first and then a pulsed magnetic field is introduced. The magnetic field is turned on when the casting length is between 25% and 40% of the total length.

[0018] Preferably, in step (4), the magnetic field does not directly contact the melt, and the magnetic field is located 3 to 5 mm above the aluminum alloy.

[0019] Preferably, in step (4), the magnetic induction intensity is controlled at 150-200mT, the frequency is controlled at 40-60Hz, the pulse interval is 20-40ms, the positive pulse duty cycle is 15%, and the pulse time is 30-50s.

[0020] Preferably, the water temperature in step (5) is 20°C.

[0021] The principle of this invention is as follows: Applying a pulsed magnetic field to molten aluminum alloy can reduce the formation of α-Al clusters and increase their number. The gradient distribution of magnetic induction intensity in the melt generates an induced current, altering the melt's viscosity. Due to the penetration of magnetic field energy, the internal structure of the clusters fluctuates, reducing the cluster decomposition rate and causing the clusters to spontaneously transform towards the critical size, ultimately leading to an increase in the number of clusters in the melt. Furthermore, the magnetic field generates a polarization effect on solute atoms, causing spontaneous atomic diffusion and increasing the local vacancy concentration, thus promoting cluster formation.

[0022] Beneficial effects of the present invention

[0023] (1) The present invention uses pulsed magnetic field to regulate the formation of solute atomic clusters in aluminum alloys, thereby obtaining clusters of a certain size and number, and thus achieving the purpose of improving the mechanical properties of aluminum alloys.

[0024] (2) This invention employs cluster ionization + pulsed magnetic field. When the nascent clusters are in an activated and highly excited state, the external magnetic field can improve the magnetic field effect. The magnetic field treats the polarized melt, changes the energy fluctuations and structural fluctuations of cluster nucleation, and controls the number and size of clusters.

[0025] (3) The present invention uses a pulsed magnetic field and a casting process that is asynchronous, which makes the structure of each region of the ingot more uniform. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the production process for regulating aluminum alloy solute atom clusters according to the present invention.

[0027] Figure 2 This is a comparison chart of the tensile strength and hardness of aluminum alloy before and after pulsed magnetic field modulation. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0029] Example 1

[0030] The chemical composition of an aluminum alloy in Example 1 is shown in Table 1.

[0031] Table 1. Chemical composition (%) of aluminum alloys in specific embodiments of the present invention

[0032] Zr Si Cu Ni Mg margin 2.3 10.5 3 2.6 1.5 Al and unavoidable impurities

[0033] The specific preparation steps are as follows:

[0034] (1) The aluminum alloy melt was obtained by melting at 650℃ according to the composition in Table 1.

[0035] (2) The aluminum alloy melt obtained in step (1) is passed through a laser evaporation device. The laser energy and particle collisions are used to increase the vacancy concentration and create conditions for the formation of primary clusters. The laser power is 50W and the irradiation time is 30s.

[0036] (3) The aluminum alloy melt treated in step (2) is passed through a DC current to promote cluster ionization, which facilitates subsequent magnetic field control. The voltage is controlled at 30V, the current at 20μA, the temperature of the ionization process is controlled at 480℃, and the reaction time is controlled at 50ms.

[0037] (4) Then the aluminum alloy melt treated in step (3) is placed in a continuous cooling casting machine. When the casting length is 25% of the total length, the magnetic field is turned on, the pulse frequency is 40Hz, the pulse interval is 30μs, the magnetic induction intensity of the pulse magnetic field is 200mT, the positive pulse duty cycle is 15%, and the pulse processing time is 30s, and finally the aluminum alloy rod is obtained.

[0038] (5) The aluminum alloy rod obtained in step (4) is quenched in water at 20°C to obtain a high-strength and high-toughness aluminum alloy material.

[0039] The hardness and room temperature tensile strength of different regions of the aluminum alloy sample were measured using a microhardness tester and a universal tensile test. The results are shown in Table 2. Table 2 shows that the core hardness of the aluminum alloy is higher than that of the edges, which is due to the increased atomic cluster density in the core caused by asynchronous rolling. Furthermore, the tensile strength is improved compared to ordinary aluminum alloys (260 MPa).

[0040] Table 2. Results of hardness and room temperature tensile strength of aluminum alloy material in different regions of Example 1.

[0041] Edge hardness HV Heart hardness HV Tensile strength (MPa) 130 138 320

[0042] Example 2

[0043] The chemical composition of an aluminum alloy according to the present invention is shown in Table 3.

[0044] Table 3 Chemical composition (%) of aluminum alloy in Example 2

[0045] Zr Si Cu Ni Mg margin 2 10 3 2 1 Al and unavoidable impurities

[0046] The specific preparation steps are as follows:

[0047] (1) The aluminum alloy melt was obtained by melting at 700℃ according to the composition in Table 3.

[0048] (2) The aluminum alloy melt obtained in step (1) is passed through a laser evaporation device. The laser energy and particle collisions are used to increase the vacancy concentration and create conditions for the formation of primary clusters. The laser power is 30W and the irradiation time is 40s.

[0049] (3) The aluminum alloy melt treated in step (2) is passed through a DC current to promote cluster ionization, which facilitates subsequent magnetic field control. The voltage is controlled at 15V, the current at 10μA, the temperature of the ionization process is controlled at 480℃, and the reaction time is controlled at 30ms.

[0050] (4) Then the aluminum alloy melt treated in step (3) is placed in a continuous cooling casting machine. When the casting length is 32.5% of the total length, the magnetic field is turned on, the pulse frequency is 60Hz, the pulse interval is 20μs, the magnetic induction intensity of the pulse magnetic field is 150mT, the positive pulse duty cycle is 15%, and the pulse processing time is 50s, and finally the aluminum alloy rod is obtained.

[0051] (5) The aluminum alloy rod obtained in step (4) is quenched in water at 20°C to obtain a high-strength and high-toughness aluminum alloy material.

[0052] The hardness and room temperature tensile strength of different regions of the aluminum alloy sample were measured using a microhardness tester and a universal tensile test. The results are shown in Table 4. Table 4 shows that the core of the aluminum alloy has a higher hardness than the edge, which is due to the increased atomic cluster density in the core caused by asynchronous rolling. Furthermore, the tensile strength is higher than that of ordinary aluminum alloy (260 MPa). Increasing the pulse processing time decreases the tensile strength; this is because excessive polarization causes atomic spin magnetic moments to rearrange, leading to a decrease in atomic vacancy concentration and cluster density.

[0053] Table 4. Results of hardness and room temperature tensile strength of aluminum alloy material in different regions in Example 2.

[0054] Edge hardness / HV Heart hardness / HV Tensile strength / MPa 129 134 311

[0055] Example 3

[0056] The chemical composition of an aluminum alloy according to the present invention is shown in Table 5.

[0057] Table 5 Chemical composition (%) of aluminum alloy in Example 3

[0058] Zr Si Cu Ni Mg margin 2.6 12 6 3 1.5 Al and unavoidable impurities

[0059] (1) The aluminum alloy melt was obtained by melting at 750℃ according to the composition in Table 5.

[0060] (2) The aluminum alloy melt obtained in step (1) is passed through a laser evaporation device. The laser energy and particle collisions are used to increase the vacancy concentration and create conditions for the formation of primary clusters. The laser power is 30W and the irradiation time is 50s.

[0061] (3) The aluminum alloy melt treated in step (2) is passed through a DC current to promote cluster ionization, which facilitates subsequent magnetic field control. The voltage is controlled at 10V, the current at 10μA, the temperature of the ionization process is controlled at 440℃, and the reaction time is controlled at 50ms.

[0062] (4) Then the aluminum alloy melt treated in step (3) is placed in a continuous cooling casting machine. When the casting length is 40% of the total length, the magnetic field is turned on, the pulse frequency is 50Hz, the pulse interval is 40μs, the magnetic induction intensity of the pulse magnetic field is 150mT, the positive pulse duty cycle is 15%, and the pulse treatment time is 50s, and finally the aluminum alloy rod is obtained.

[0063] (5) The aluminum alloy rod obtained in step (4) is quenched in water at 20°C to obtain a high-strength and high-toughness aluminum alloy material.

[0064] The hardness and room temperature tensile strength of different regions of the aluminum alloy sample were measured using a microhardness tester and a universal tensile test. The results are shown in Table 6. Table 6 shows that the core hardness of the aluminum alloy is higher than that of the edges, which is due to the increased atomic cluster density in the core caused by asynchronous rolling. Furthermore, the tensile strength is higher than that of ordinary aluminum alloy (260 MPa). With further increases in pulse treatment time, the tensile strength increases again. This is because prolonged magnetic field pulses may induce atomic migration or diffusion, providing sufficient energy for atoms to cross potential barriers. This migration or diffusion process may lead to an increase in atomic vacancy concentration.

[0065] Table 6. Results of hardness and room temperature tensile strength properties of aluminum alloy materials in different regions of Example 3.

[0066] Edge hardness / HV Heart hardness / HV Tensile strength / MPa 127 136 318

[0067] Comparative Example 1

[0068] The only difference between this embodiment and Embodiment 1 is that in step (4), only casting is performed, without pulsed magnetic field treatment. The raw materials and other preparation processes are the same as in Embodiment 1, specifically:

[0069] (1) The aluminum alloy melt was obtained by melting at 650℃ according to the composition in Table 1.

[0070] (2) The aluminum alloy melt obtained in step (1) is passed through a laser evaporation device. The laser energy and particle collisions are used to increase the vacancy concentration and create conditions for the formation of primary clusters. The laser power is 50W and the irradiation time is 30s.

[0071] (3) The aluminum alloy melt treated in step (2) is passed through a DC current to promote cluster ionization, which facilitates subsequent magnetic field control. The voltage is controlled at 30V, the current at 20μA, the temperature of the ionization process is controlled at 480℃, and the reaction time is controlled at 50ms.

[0072] (4) Then the aluminum alloy melt treated in step (3) is placed in a continuous cooling casting machine, and the casting length is 25% of the total length, finally obtaining an aluminum alloy rod.

[0073] (5) The aluminum alloy rod obtained in step (4) is quenched in water at 20°C to obtain a high-strength and high-toughness aluminum alloy material.

[0074] The hardness and room temperature tensile strength of different regions of the aluminum alloy sample were measured using a microhardness tester and a universal tensile test. The results are shown in Table 7. The table shows that without pulsed magnetic field treatment, the hardness and tensile strength of each region decreased significantly. This is because magnetic field treatment increases the vacancy concentration and thus the cluster density. Clusters are short-range ordered structures, which significantly improve the strength and toughness of the aluminum alloy. Figure 2 It can also be seen that without pulsed magnetic field treatment, the hardness and tensile strength of each region decrease significantly.

[0075] Table 7. Results of hardness and room temperature tensile strength of aluminum alloy materials in different regions of Comparative Example 1.

[0076] Edge hardness HV Heart hardness HV Tensile strength (MPa) 108 114 262

[0077] Comparative Example 2

[0078] In contrast, the only difference in Example 2 is that the laser irradiation treatment in step (2) is omitted. The raw materials and the remaining steps are the same as in Example 2, specifically:

[0079] (1) The aluminum alloy melt was obtained by melting at 700℃ according to the composition in Table 3.

[0080] (2) The aluminum alloy melt obtained in step (1) is passed through a DC current to promote cluster ionization, which facilitates subsequent magnetic field control. The voltage is controlled at 15V, the current at 10μA, the temperature of the ionization process is controlled at 480℃, and the reaction time is controlled at 30ms.

[0081] (3) Then the aluminum alloy melt treated in step (2) is placed in a continuous cooling casting machine. When the casting length is 32.5% of the total length, the magnetic field is turned on, the pulse frequency is 60Hz, the pulse interval is 30μs, the magnetic induction intensity of the pulse magnetic field is 150mT, the positive pulse duty cycle is 15%, and the pulse processing time is 40s, and finally the aluminum alloy rod is obtained.

[0082] (4) The aluminum alloy rod obtained in step (3) is quenched in water at 20°C to obtain a high-strength and high-toughness aluminum alloy material.

[0083] The hardness and room temperature tensile strength of different regions of the aluminum alloy sample were measured by a microhardness tester and a universal tensile test. The measurement results are shown in Table 8. It can be seen from the table that compared with Comparative Example 1 without any treatment, the tensile strength and hardness of each region were significantly improved after magnetic field treatment. However, since laser irradiation was not used to reduce the energy barrier of vacancy migration, the cluster concentration was still not high enough compared with laser irradiation, and the tensile strength and hardness were low.

[0084] Table 8. Results of hardness and room temperature tensile strength of aluminum alloy materials in different regions of Comparative Example 2.

[0085] Edge hardness / HV Heart hardness / HV Tensile strength / MPa 116 124 287

[0086] Comparative Example 3

[0087] As a comparison, the only difference from Example 3 is that step (3) is not performed; all other processes and raw materials are the same as in Example 3. The specific operating steps are as follows:

[0088] (1) The aluminum alloy melt was obtained by melting at 750℃ according to the composition in Table 5.

[0089] (2) The aluminum alloy melt obtained in step (1) is passed through a laser evaporation device. The laser energy and particle collisions are used to increase the vacancy concentration and create conditions for the formation of primary clusters. The laser power is 30W and the irradiation time is 50s.

[0090] (3) Then the aluminum alloy melt treated in step (2) is placed in a continuous cooling casting machine. When the casting length is 40% of the total length, the magnetic field is turned on, the pulse frequency is 50Hz, the pulse interval is 30μs, the magnetic induction intensity of the pulse magnetic field is 150mT, the positive pulse duty cycle is 15%, and the pulse processing time is 50s, and finally the aluminum alloy rod is obtained.

[0091] (4) The aluminum alloy rod obtained in step (3) is quenched in water at 20°C to obtain a high-strength and high-toughness aluminum alloy material.

[0092] The hardness and room temperature tensile strength of different regions of the aluminum alloy sample were measured by a microhardness tester and a universal tensile test. The measurement results are shown in Table 9. It can be seen from the table that the core hardness is not high enough without DC treatment. This is because DC can apply a pre-polarization effect to the atoms in the core. When the magnetic field is treated in the subsequent process, the relaxation degree of the atomic magnetic moment increases, the migration of vacancies increases, and the cluster concentration increases, so that the core hardness can be higher.

[0093] Table 9. Results of hardness and room temperature tensile strength of aluminum alloy materials in different regions of Comparative Example 3.

[0094] Edge hardness / HV Heart hardness / HV Tensile strength / MPa 124 118 302

Claims

1. A process for achieving strengthening and toughening of aluminum alloys by regulating solute atomic clusters in aluminum alloys, characterized by: A process combining cluster ionization with pulsed magnetic field treatment, and asynchronous magnetic field and casting processes, is used to strengthen and toughen aluminum alloys. The specific processing steps are as follows: (1) Aluminum alloy melt is obtained by melting Si, Mg, Cu, Zr, Ni, Al and unavoidable impurities; (2) The aluminum alloy melt obtained in step (1) is subjected to laser irradiation treatment using a laser evaporation device; (3) The aluminum alloy melt treated in step (2) is then subjected to direct current; (4) The aluminum alloy melt treated in step (3) is placed in a continuous cooling casting machine and a pulsed magnetic field is introduced to obtain aluminum alloy bars; (5) The aluminum alloy bar treated in step (4) is water quenched to obtain aluminum alloy material; In step (2), the laser power is controlled at 30-50W and the irradiation time is 30-50s; In step (3), the DC voltage is controlled at 10 ~ 30V, the current is 10 ~ 20μA, the temperature of the ionization process should be 500℃ lower than the nucleation temperature, and the ionization is more complete when the temperature is controlled at 440 ~ 480℃. The reaction time is controlled at 30 ~ 50ms. In step (4), casting is performed first, and then a pulsed magnetic field is introduced. The magnetic field is turned on when the casting length is 25 to 40% of the total length. In step (4), the magnetic induction intensity is controlled at 150 ~ 200mT, the frequency is controlled at 40 ~ 60Hz, the pulse interval is 20 ~ 40μs, the positive pulse duty cycle is 15%, and the pulse time is 30 ~ 50s.

2. The process for achieving strengthening and toughening of aluminum alloys by modulating solute atomic clusters in aluminum alloys as claimed in claim 1, wherein: In step (1), the total mass percentage of Si, Mg, Cu, Zr, Ni, Al and unavoidable impurities is 100%, which includes 10 ~ 12% Si, 1 ~ 1.5% Mg, 3 ~ 6% Cu, 2 ~ 2.6% Zr, 2 ~ 3% Ni, and the balance is Al and unavoidable impurities.

3. The process for strengthening and toughening aluminum alloys by controlling the atomic clusters of aluminum alloy solutes according to claim 1, characterized in that: The melting temperature in step (1) is 650 ~ 750℃.

4. The process for strengthening and toughening aluminum alloys by controlling the atomic clusters of aluminum alloy solutes according to claim 1, characterized in that: In step (4), the magnetic field does not directly contact the melt; the magnetic field is located 3 to 5 mm above the aluminum alloy.

5. The process for achieving strengthening and toughening of aluminum alloys by modulating solute atomic clusters in aluminum alloys as claimed in claim 1 wherein: In step (5), the water temperature during water quenching is 20℃.

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