Aluminum-copper-lithium alloy, preparation method thereof and recrystallization regulation and control method

Abstract

The invention provides an aluminum-copper-lithium alloy, a preparation method of the aluminum-copper-lithium alloy and a recrystallization regulation and control method. The preparation method comprises the steps that industrial grade pure aluminum, an aluminum-copper alloy and an aluminum-zirconium alloy are jointly heated to 700-800 DEG C to be melted, silver particles, pure magnesium and pure lithium are sequentially added after the industrial grade pure aluminum, the aluminum-copper alloy and the aluminum-zirconium alloy are completely melted, the weight part of the industrial grade pure aluminum is 21-23, the weight part of the aluminum-copper alloy is 2.8-3.0, and the weight part of the aluminum-zirconium alloy is 1.5-2.5. The weight part of the aluminum-zirconium alloy is 0.02 to 0.03 part, the weight part of the silver particles is 0.09 to 1 part, the weight part of the pure magnesium is 0.12 to 0.14 part, and the weight part of the pure lithium is 0.29 to 0.31 part; and after all the metals are molten, refining to remove impurities, then injecting into a mold, and cooling and solidifying to obtain the aluminum-copper-lithium alloy. According to the aluminum-copper-lithium alloy provided by the invention, precipitation and dissolution of Ag3Al particles can be regulated and controlled through a proper heat treatment process, so that recrystallization regulation and control of the aluminum-copper-lithium alloy are realized, and the formability and machinability required by different components are met.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy processing, and in particular relates to an aluminum-copper-lithium alloy and a preparation method thereof and a recrystallization control method. Background Art

[0002] Compared with traditional aluminum alloys, the weight of aluminum-copper-lithium alloy is reduced by 10% to 20%, and the stiffness is increased by 15% to 20%, while maintaining high specific strength, excellent fatigue resistance and strong corrosion resistance. These characteristics make Al-Cu-Li alloy an ideal structural material in the aerospace field.

[0003] Although the molten-cast Al-Cu-Li alloy can form complex parts, there are serious element segregation, grain boundary segregation and coarse second phases in the molten-cast Al-Cu-Li alloy. These microstructural heterogeneities reduce the performance, toughness and ductility of the alloy during extrusion, forging and rolling. Homogenization annealing heats the alloy to a high temperature and keeps it warm for a long time, which can promote the dissolution of coarse primary phases and reduce the segregation of solute elements. At the same time, the homogenization process redistributes the solute elements and further promotes the precipitation of nano-dispersed phases to refine the microstructure of the alloy. The homogenization process can effectively solve the heterogeneity problem of the molten-cast alloy.

[0004] Microalloying technology plays an important role in improving the microstructure of aluminum-copper-lithium alloys. For example, adding microelements such as Mn, Zr and Ce to Al-Cu-Li alloys will form a uniform and dense Al-Cu-Li alloy during homogenization annealing. 20 Nano-scale precipitate particles such as Cu2Mn3, Al3Zr and Al8Cu4Ce, as a high-temperature stable phase, will pin dislocations and subgrain boundary migration during thermal deformation, and can often only inhibit the recrystallization of the alloy, but cannot promote recrystallization. Since recrystallization can improve the formability and machinability of the alloy, if the microstructure recrystallization of the alloy is inhibited, the formability of parts with complex cross-sections will be reduced, especially for parts with high ribs formed by extrusion. If the alloy recrystallization is inhibited, the skin or ribs will often not be fully formed. Therefore, the recrystallization regulation of Al-Cu-Li alloy has become a problem that needs to be solved. Summary of the invention

[0005] The object of the present invention is to provide an aluminum-copper-lithium alloy with adjustable recrystallization. After the alloy is subjected to linear temperature rising homogenization heat treatment, the Ag3Al particles in the aluminum-copper-lithium alloy are in a precipitation state, thereby inhibiting the recrystallization of the aluminum-copper-lithium alloy. After the alloy is subjected to linear temperature rising homogenization heat treatment and 470°C insulation treatment, the Ag3Al precipitate particles in the aluminum-copper-lithium alloy are dissolved back into the matrix, thereby promoting the recrystallization of the aluminum-copper-lithium alloy, thereby achieving adjustable recrystallization of the aluminum-copper-lithium alloy.

[0006] In order to achieve the above-mentioned object, the present invention provides a method for preparing an aluminum-copper-lithium alloy with adjustable recrystallization, the preparation method comprising: step 1), heating industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy together to 700-800°C for melting, and adding silver particles, pure magnesium and pure lithium in sequence after the industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy are completely melted, wherein the weight portion of industrial-grade pure aluminum is 21-23 parts, the weight portion of aluminum-copper alloy is 2.8-3.0 parts, the weight portion of aluminum-zirconium alloy is 0.02-0.03 parts, the weight portion of silver particles is 0.09-1 parts, the weight portion of pure magnesium is 0.12-0.14 parts, and the weight portion of pure lithium is 0.29-0.31 parts; step 2), after all metals are completely melted, refining to remove impurities, and then injecting into a mold, cooling and solidifying to obtain a molten aluminum-copper-lithium alloy.

[0007] In a specific embodiment, based on the total weight of the aluminum-copper alloy being 100%, the mass fraction of copper in the aluminum-copper alloy is 50%; based on the total weight of the aluminum-zirconium alloy being 100%, the mass fraction of zirconium in the aluminum-zirconium alloy is 10%.

[0008] In a specific embodiment, the adding of silver particles, pure magnesium and pure lithium in sequence after the industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy are completely melted is specifically: adding pure magnesium after the silver particles are completely melted, and adding pure lithium after the pure magnesium is completely melted.

[0009] In a specific embodiment, the step 1) comprises: step (1), preheating in a vacuum furnace, wherein the preheating temperature is 300-400°C and the preheating time is 20-30 minutes; step (2), placing industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy in a graphite crucible, and transferring them to a preheated vacuum furnace for melting, first heating from the preheating temperature to a first preset temperature, and then keeping the temperature for 30 minutes, wherein the first preset temperature is 700-800°C; step (3), after the first preset temperature is kept, all the metals in the graphite crucible are completely melted, silver particles are added to the melt, and then the vacuum furnace temperature is set to a second preheating temperature. The step (4) is to add pure Mg to the melt after the second preset temperature is maintained for 10 to 20 minutes, and to keep the temperature for 10 to 20 minutes to completely melt the silver particles, wherein the second preset temperature is 700 to 750°C; the step (4) is to continue to add pure Mg to the melt under argon protection after the second preset temperature is maintained, and to continue to maintain the temperature for 5 to 10 minutes under stirring at the third preset temperature, and to add pure Li after the Mg is completely melted during the maintenance process, wherein the third preset temperature is 700 to 720°C; the step (5) is to refine the melt to remove impurities after the third preset temperature is maintained, and then inject the melt into a mold, and cool and solidify the melt to obtain a molten aluminum-copper-lithium alloy.

[0010] The present invention also provides an aluminum-copper-lithium alloy with controllable recrystallization, and the aluminum-copper-lithium alloy is prepared by the preparation method described above.

[0011] The present invention also provides a method for regulating the recrystallization of an aluminum-copper-lithium alloy, the method comprising the following steps: step S10, providing an aluminum-copper-lithium alloy, wherein the aluminum-copper-lithium alloy is the aluminum-copper-lithium alloy as described in claim 5; step S20, performing a linear temperature increase homogenization heat treatment on the aluminum-copper-lithium alloy, so that the Ag3Al particles in the aluminum-copper-lithium alloy are in a precipitation state, thereby inhibiting the recrystallization of the aluminum-copper-lithium alloy.

[0012] In a specific embodiment, the linear temperature rise homogenization heat treatment includes: first heating the aluminum-copper-lithium alloy from room temperature to 440°C at a preset heating rate, then keeping it at 440°C for 8 hours, then heating the aluminum-copper-lithium alloy from 440°C to 510°C at the preset heating rate, keeping it at that temperature for 24 hours, and then air cooling it to room temperature.

[0013] In a specific embodiment, the method also includes a step S30 after step S20, wherein: step S30, heat treating the aluminum-copper-lithium alloy obtained by the linear heating homogenization heat treatment of step S20 according to a preset heat treatment method, so that the Ag3Al precipitate particles in the aluminum-copper-lithium alloy are dissolved back into the matrix, thereby promoting the recrystallization of the aluminum-copper-lithium alloy.

[0014] In a specific embodiment, the preset heat treatment method of step S30 is specifically: heating the aluminum-copper-lithium alloy obtained by the linear temperature increase homogenization heat treatment of step S20 from room temperature to 470°C, and keeping it warm for 1 hour, and performing quenching treatment after the insulation is completed.

[0015] The present invention also provides an aluminum-copper-lithium alloy obtained by the regulation method described above.

[0016] The beneficial effects of the present invention include at least:

[0017] 1. The present invention provides a method for preparing an aluminum-copper-lithium alloy with adjustable recrystallization, the method comprising: step 1), heating industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy to 700-800° C. for melting, and adding silver particles, pure magnesium and pure lithium in sequence after the industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy are completely melted, wherein the weight proportion of industrial-grade pure aluminum is 21-23 parts, the weight proportion of aluminum-copper alloy is 2.8-3.0 parts, the weight proportion of aluminum-zirconium alloy is 0.02-0.03 parts, the weight proportion of silver particles is 0. .09 to 1 part, the weight portion of pure magnesium is 0.12 to 0.14 parts, and the weight portion of pure lithium is 0.29 to 0.31 parts; step 2), after all the metals are melted, they are refined to remove impurities, and then injected into a mold, and cooled and solidified to obtain a molten aluminum-copper-lithium alloy; in this way, a new type of aluminum-copper-lithium alloy is melt-cast based on the preparation method provided by the present invention, and the precipitation and dissolution of Ag3Al particles can be regulated by a suitable heat treatment process, thereby realizing the regulation of recrystallization of the aluminum-copper-lithium alloy and meeting the formability and machinability required by different components.

[0018] 2. The aluminum-copper-lithium alloy is subjected to a linear temperature rise homogenization heat treatment, and the Ag3Al particles in the aluminum-copper-lithium alloy are in a precipitated state, thereby inhibiting the recrystallization of the aluminum-copper-lithium alloy, and is suitable for forming components with simple cross-sections; the aluminum-copper-lithium alloy obtained by the linear temperature rise homogenization heat treatment is subjected to a 470°C / 1h heat treatment, and the Ag3Al precipitate particles in the aluminum-copper-lithium alloy are dissolved back into the matrix, thereby promoting the recrystallization of the aluminum-copper-lithium alloy, and is suitable for forming covered belt high-rib components through an extrusion process, etc.; in this way, the recrystallization performance of the alloy is controllable, so that the alloy can meet the forming and processing requirements of components of different sizes, which is of great significance for promoting a wider range of engineering applications of Al-Cu-Li alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A flow chart of the steps of the method for regulating the recrystallization of the aluminum-copper-lithium alloy provided by the present invention;

[0020] Figure 2 Schematic diagram of compression and sampling corresponding to Embodiment 2 and Embodiment 3 of the present invention;

[0021] Figure 3 This is a diagram showing the characterization results of the recrystallization structure of the cylindrical sample A provided in Example 2 of the present invention after hot compression;

[0022] Figure 4 TEM image of sample 1 prepared in Example 2 of the present invention;

[0023] Figure 5 This is a diagram showing the characterization results of the recrystallization structure of the cylindrical sample B provided in Example 3 of the present invention after hot compression. DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to the accompanying drawings and embodiments, but the present invention can be implemented in many different ways as limited and covered by the claims.

[0025] The present invention generally relates to a novel aluminum-copper-lithium alloy, a preparation method thereof and a recrystallization control method of the novel aluminum-copper-lithium alloy.

[0026] In order to improve the mechanical properties of alloy materials and extend the service life of materials, the prior art discloses suppressing the recrystallization performance of aluminum-copper-lithium alloys by adding inhibitors, optimizing processing technology, etc., and after the recrystallization of the alloy is suppressed, recrystallization promotion cannot be formed, which will affect the formability and processability of the alloy. For example, when forming parts with high ribs on the skin by extrusion process, if the alloy recrystallization is suppressed, the skin or ribs will often not be fully formed. The present invention improves the formula of the existing aluminum alloy to provide a new type of aluminum-copper-lithium alloy. The alloy can control the precipitation and dissolution of Ag3Al particles through a suitable heat treatment process, and the recrystallization control of the alloy can be achieved, thereby meeting different forming requirements.

[0027] The present invention provides a method for preparing an aluminum-copper-lithium alloy with controllable recrystallization, the preparation method comprising:

[0028] Step 1), heating industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy together to 700-800° C. for melting, and adding silver particles, pure magnesium and pure lithium in sequence after the industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy are completely melted, wherein the weight portion of industrial-grade pure aluminum is 21-23 parts, the weight portion of aluminum-copper alloy is 2.8-3.0 parts, the weight portion of aluminum-zirconium alloy is 0.02-0.03 parts, the weight portion of silver particles is 0.09-1 parts, the weight portion of pure magnesium is 0.12-0.14 parts, and the weight portion of pure lithium is 0.29-0.31 parts.

[0029] Preferably, the adding of silver particles, pure magnesium and pure lithium in sequence after the industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy are completely melted is specifically: adding pure magnesium after the silver particles are completely melted, and adding pure lithium after the pure magnesium is completely melted.

[0030] Preferably, the step 1) comprises:

[0031] Step (1), preheating in a vacuum furnace, wherein the preheating temperature is 300-400° C. and the preheating time is 20-30 minutes.

[0032] Step (2), placing industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy in a graphite crucible, and transferring them to a preheated vacuum furnace for melting, first heating from the preheating temperature to a first preset temperature, and then keeping the temperature for 30 minutes, wherein the first preset temperature is 700-800°C.

[0033] Step (3), after the first preset temperature is maintained, all the metal in the graphite crucible has been completely melted, silver particles are added to the melt, and then the vacuum furnace temperature is set to a second preset temperature and maintained for 10 min to 20 min to completely melt the silver particles, wherein the second preset temperature is 700 to 750°C.

[0034] Step (4), after the insulation at the second preset temperature is completed, pure Mg is continued to be added to the melt under the protection of argon, and the melt is continued to be heated at the third preset temperature for 5 minutes to 10 minutes under stirring. During the insulation process, pure Li is added after Mg is completely melted, wherein the third preset temperature is 700 to 720°C.

[0035] Step (5), after the third preset temperature is maintained, the melt is refined to remove impurities, and then injected into a mold, cooled and solidified to obtain a molten aluminum-copper-lithium alloy.

[0036] Preferably, the heating rate from the preheating temperature to the first preset temperature is 200° C. / h.

[0037] Preferably, the second preset temperature is the same as the third preset temperature, and the first preset temperature is greater than the second preset temperature and the third preset temperature.

[0038] More preferably, the first preset temperature is 750°C, and the second preset temperature and the third preset temperature are 720°C.

[0039] Step 2) After all the metals are melted, they are refined to remove impurities and then poured into a mold to be cooled and solidified to obtain a molten aluminum-copper-lithium alloy.

[0040] Preferably, based on the total weight of the aluminum-copper alloy being 100%, the mass fraction of copper in the aluminum-copper alloy is 50%; based on the total weight of the aluminum-zirconium alloy being 100%, the mass fraction of zirconium in the aluminum-zirconium alloy is 10%.

[0041] The present invention also provides an aluminum-copper-lithium alloy with controllable recrystallization, and the aluminum-copper-lithium alloy is prepared by the preparation method described above.

[0042] See also Figure 1 The present invention also provides a method for regulating the recrystallization of an aluminum-copper-lithium alloy, the method comprising the following steps:

[0043] Step S10: providing an aluminum-copper-lithium alloy.

[0044] The aluminum-copper-lithium alloy is an aluminum-copper-lithium alloy prepared by the preparation method described above, which will not be described in detail here.

[0045] Step S20, performing a linear temperature increase homogenization heat treatment on the aluminum-copper-lithium alloy to place the Ag3Al particles in the aluminum-copper-lithium alloy in a precipitation state, thereby inhibiting the recrystallization of the aluminum-copper-lithium alloy.

[0046] Preferably, the linear temperature rise homogenization heat treatment includes: first heating the aluminum-copper-lithium alloy from room temperature to 440°C at a preset heating rate, then keeping it at 440°C for 8 hours, then heating the aluminum-copper-lithium alloy from 440°C to 510°C at the preset heating rate, keeping it at that temperature for 24 hours, and then air cooling it to room temperature.

[0047] In the present invention, the alloy is subjected to linear temperature increase homogenization heat treatment to improve the inhomogeneity of the microstructure of the Al-Cu-Li alloy in the molten-cast state, such as element segregation, grain boundary segregation and coarse second phase.

[0048] Preferably, the preset heating rate is 25°C / h.

[0049] Preferably, the method further comprises step S30 after step S20, wherein:

[0050] Step S30, heat treating the aluminum-copper-lithium alloy obtained by the linear heating homogenization heat treatment in step S20 according to a preset heat treatment method, so that the Ag3Al precipitate particles in the aluminum-copper-lithium alloy are dissolved back into the matrix to promote the recrystallization of the aluminum-copper-lithium alloy.

[0051] Preferably, the preset heat treatment method of step S30 is specifically: heating the aluminum-copper-lithium alloy obtained by the linear temperature increase homogenization heat treatment of step S20 from room temperature to 470°C, and keeping it warm for 1 hour, and performing quenching treatment after the end of the insulation.

[0052] The present invention also provides an aluminum-copper-lithium alloy, which is obtained by subjecting the aluminum-copper-lithium alloy with adjustable recrystallization to a linear heating homogenization heat treatment.

[0053] Preferably, the linear temperature rise homogenization heat treatment includes: first heating the aluminum-copper-lithium alloy from room temperature to 440°C at a preset heating rate, then keeping it at 440°C for 8 hours, then heating the aluminum-copper-lithium alloy from 440°C to 510°C at the preset heating rate, keeping it at that temperature for 24 hours, and then air cooling it to room temperature.

[0054] It can be understood that the aluminum-copper-lithium alloy here is an aluminum-copper-lithium alloy in which recrystallization is suppressed.

[0055] The present invention also provides an aluminum-copper-lithium alloy, which is obtained by sequentially subjecting the recrystallization-controllable aluminum-copper-lithium alloy to a linear temperature increase homogenization heat treatment and a preset heat treatment method.

[0056] Preferably, the linear temperature rise homogenization heat treatment includes: first heating the aluminum-copper-lithium alloy from room temperature to 440°C at a preset heating rate, then keeping it at 440°C for 8 hours, then heating the aluminum-copper-lithium alloy from 440°C to 510°C at the preset heating rate, keeping it warm for 24 hours, and then air cooling it to room temperature; the preset heat treatment method is specifically: heating the aluminum-copper-lithium alloy obtained by the linear temperature rise homogenization heat treatment from room temperature to 470°C, keeping it warm for 1 hour, and performing quenching treatment after the insulation is completed.

[0057] It can be understood that the aluminum-copper-lithium alloy here is an aluminum-copper-lithium alloy in which recrystallization is promoted.

[0058] Example 1

[0059] Preparation of copper-aluminum-lithium alloy with controllable recrystallization

[0060] Step 1: Preheating the vacuum furnace. Specifically, set the temperature of the vacuum furnace to 400°C and the preheating time to 20 minutes.

[0061] Step 2: Place 22.5 kg of industrial pure aluminum, 2.85 kg of Al-50% wt Cu alloy and 0.026 kg of Al-10% wt Zr alloy in a graphite crucible, transfer to a preheated vacuum furnace, set the vacuum furnace temperature to 750° C., and keep warm for 30 minutes.

[0062] Step 3: After being kept at 750°C for 30 minutes, the melt in the graphite crucible is completely melted. 0.10 kg of silver particles are added to the melt, and the vacuum furnace temperature is set to 720°C and kept at this temperature for 20 minutes to completely melt the silver particles.

[0063] Step 4: After keeping the temperature at 720°C for 20 minutes, 0.13 kg of pure Mg was added under argon protection, and the temperature was kept at 720°C for 10 minutes under stirring. During the heat preservation process, 0.3 kg of pure Li was added after Mg was completely melted.

[0064] Step 5: After keeping at 720°C for 10 minutes, the melt is refined to remove impurities, and then the melt is poured into a preheated cylindrical metal mold coated with boron nitride, and cooled and solidified to obtain a molten aluminum-copper-lithium alloy.

[0065] The chemical composition of the aluminum-copper-lithium alloy was measured by elemental analysis using an inductively coupled plasma emission spectrometer (ICP): Cu: 5.47wt%, Li: 1.19wt%, Mg: 0.51wt%, Ag: 0.38wt%, Fe: 0.078wt%, Mn: 0.012wt%, Zr: 0.01wt%, Ti: 0.002wt%, Zn: 0.006wt%, Si: 0.006wt%, and the remainder is aluminum, expressed as Al-5.47Cu-1.19Li-0.51Mg-0.38Ag-0.078Fe-0.012Mn-0.01Zr-0.002Ti-0.006Zn-0.006Si (wt.%), abbreviated as: Al-5.47Cu-1.19Li-0.51Mg-0.38Ag alloy.

[0066] Example 2

[0067] Control method for inhibiting recrystallization of aluminum-copper-lithium alloy

[0068] The Al-5.47Cu-1.19Li-0.51Mg-0.38Ag alloy was subjected to linear heating homogenization heat treatment. The specific heat treatment process was as follows: heating from room temperature to 440°C at a heating rate of 25°C / h, keeping at 440°C for 8 hours, then heating from 440°C to 510°C at a heating rate of 25°C / h, and then keeping at this temperature for 24 hours. Subsequently, the sample was taken out of the heating furnace and air-cooled to room temperature to obtain sample 1.

[0069] In order to characterize the dynamic recrystallization fraction of the alloy, a cylindrical sample A with a diameter of 8 mm and a length of 12 mm was taken from the center of the alloy (sample 1) after linear temperature rise heat treatment, and the cylindrical sample A was hot compressed using a Gleeble3180 thermal simulator. The hot compression conditions were: the heating temperature of the cylindrical sample A was 450 ° C, the strain rate was 0.15s -1 , the cylindrical sample A is compressed to 70% along the length direction of the cylindrical sample. To prevent the grains from growing further after compression, the cylindrical sample A is immediately removed from the thermal simulator after compression and placed in a container with water medium. Then, the center of the compressed cylindrical sample A is sampled by wire cutting. The sampling area is as follows: Figure 2As shown, the sample is firstly rough ground to make the two end faces of the sample flat, one of the end faces is pasted on the counterweight, and the other end face is ground with 800 mesh sandpaper, 1500 mesh sandpaper, 2000 mesh sandpaper, and 400 mesh sandpaper in turn, and then the red velvet polishing cloth is replaced with grinding pastes of 2.5μm, 1.5μm, and 0.5μm in turn to continue grinding the end face of the sample until the end face of the sample is ground to a mirror state. Finally, the porous chloroprene rubber polishing cloth is replaced with a silica polishing liquid with a particle size of 0.05μm to continue suspending the mirror sample for 3h, and finally the sample is rinsed clean for electron backscatter diffraction EBSD characterization experiment.

[0070] The recrystallization of sample 1 was analyzed by EBSD post-processing software TSL OIM analysis software, and the dynamic recrystallization structure of the sample was characterized by setting the grain orientation spread value (GOS) < 2°, such as Figure 3 As shown in the figure. After compression, the cylindrical sample A has RD as the compression direction and the grains are elongated along the TD direction. The black filled area is a completely recrystallized structure, and the recrystallization fraction of the sample is 2.3%. The low recrystallization fraction indicates that the recrystallization of the alloy is significantly suppressed after the linear temperature increase heat treatment.

[0071] The linearly heated samples were further observed by transmission electron microscopy (TEM). Figure 4 ,from Figure 4 It can be seen that Ag3Al precipitate particles can precipitate along the grain boundaries and inside the grains. These dense Ag3Al precipitate particles can pin dislocations and subgrain boundary migration during the subsequent hot deformation process, thereby inhibiting recrystallization.

[0072] According to the Ag-Al phase diagram, the μ phase (Ag3Al) will dissolve when the temperature exceeds 440°C, and the μ phase (Ag3Al) will dissolve at 450°C, while the maximum temperature of the linear heating heat treatment is 510°C. Therefore, Ag3Al is not precipitated during the insulation stage of the linear heating heat treatment, but is precipitated during the air cooling to room temperature stage. The long-term insulation makes the solute supersaturated, and the supersaturation provides conditions for the precipitation of Ag3Al during the cooling stage.

[0073] Example 3

[0074] Control method to promote recrystallization of aluminum-copper-lithium alloy

[0075] The aluminum-copper-lithium alloy prepared in Example 1 was treated according to the linear temperature increase homogenization heat treatment process provided in Example 2, and then subjected to a heat treatment at 470°C / 1h, and finally quenched to obtain Sample 2.

[0076] In order to characterize the dynamic recrystallization fraction of the alloy, sample 2 was quickly cut to obtain a cylindrical sample B with a diameter of 8 mm and a length of 12 mm, and the cylindrical sample B was quickly hot compressed. The hot compression conditions were that the sample was heated to 450 °C and the strain rate was approximately 0.15 s -1 , compress the cylindrical specimen B to 70% along the length direction of the cylindrical specimen. Take the center area of ​​the compressed specimen (refer to Figure 2 As shown), the cut sample is coarsely ground again to make the two end faces of the sample flat. One end face is pasted on the counterweight block, and the other end face is ground with 800 mesh sandpaper, 1500 mesh sandpaper, 2000 mesh sandpaper, and 400 mesh sandpaper in turn. Then, the red velvet polishing cloth is replaced with grinding pastes of 2.5μm, 1.5μm, and 0.5μm in turn to continue grinding the end face of the sample until the end face of the sample is ground to a mirror state. Finally, the porous chloroprene rubber polishing cloth is replaced with a silica polishing liquid with a particle size of 0.05μm to continue suspending the mirror sample for 3h. Finally, the sample is rinsed clean for electron backscatter diffraction EBSD characterization experiment.

[0077] The recrystallization of the samples after linear heating and 470℃ / 1h heat treatment was analyzed by EBSD post-processing software TSL OIM software, and the dynamic recrystallization structure of the samples was characterized by setting the grain orientation spread value (GOS) <2°, such as Figure 5 As shown. After compression, the cylindrical sample B has RD as the compression direction and the grains are elongated along the TD direction. The black filled area is a completely recrystallized structure, and the recrystallization fraction of the sample is 20.8%. The recrystallization fraction is significantly improved, indicating that the recrystallization of the alloy is significantly promoted after linear heating and 470℃ / 1h heat treatment.

[0078] The Al-Cu-Li alloy prepared by the preparation method provided by the present invention is subjected to linear temperature rise homogenization heat treatment, and the recrystallization of the Al-Cu-Li alloy is suppressed. The recrystallization of the Al-Cu-Li alloy is promoted after linear temperature rise homogenization heat treatment and 470°C / 1h heat treatment. In this way, the recrystallization of the alloy can be controlled, and the alloy can meet the forming and processing requirements of different components, which is of great significance for promoting a wider range of engineering applications of the Al-Cu-Li alloy.

[0079] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing an aluminum-copper-lithium alloy with controllable recrystallization, characterized in that: The preparation method comprises: Step 1), heating industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy together to 700-800° C. for melting, and adding silver particles, pure magnesium and pure lithium in sequence after the industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy are completely melted, wherein the weight portion of industrial-grade pure aluminum is 21-23 parts, the weight portion of aluminum-copper alloy is 2.8-3.0 parts, the weight portion of aluminum-zirconium alloy is 0.02-0.03 parts, the weight portion of silver particles is 0.09-1 parts, the weight portion of pure magnesium is 0.12-0.14 parts, and the weight portion of pure lithium is 0.29-0.31 parts; Step 2) After all the metals are melted, they are refined to remove impurities and then poured into a mold to be cooled and solidified to obtain a molten aluminum-copper-lithium alloy.

2. The method for preparing an aluminum-copper-lithium alloy with controllable recrystallization according to claim 1, characterized in that: Taking the total weight of the aluminum-copper alloy as 100%, the mass fraction of copper in the aluminum-copper alloy is 50%; taking the total weight of the aluminum-zirconium alloy as 100%, the mass fraction of zirconium in the aluminum-zirconium alloy is 10%.

3. The method for preparing an aluminum-copper-lithium alloy with controllable recrystallization according to claim 1 or 2, characterized in that: The step of sequentially adding silver particles, pure magnesium and pure lithium after the industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy are completely melted is specifically as follows: adding pure magnesium after the silver particles are completely melted, and adding pure lithium after the pure magnesium is completely melted.

4. The method for preparing the aluminum-copper-lithium alloy with controllable recrystallization according to claim 3, characterized in that: The step 1) comprises: Step (1), preheating in a vacuum furnace, wherein the preheating temperature is 300-400° C. and the preheating time is 20-30 min; Step (2), placing industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy in a graphite crucible, and transferring to a preheated vacuum furnace for melting, first heating from the preheating temperature to a first preset temperature, and then keeping the temperature for 30 minutes, wherein the first preset temperature is 700-800° C.; Step (3), after the first preset temperature is maintained, all the metal in the graphite crucible is completely melted, silver particles are added to the melt, and then the vacuum furnace temperature is set to a second preset temperature, and the temperature is maintained for 10 min to 20 min to completely melt the silver particles, wherein the second preset temperature is 700 to 750° C.; Step (4), after the second preset temperature is maintained, pure Mg is continued to be added to the melt under argon protection, and the melt is maintained at a third preset temperature for 5 to 10 minutes under stirring. During the maintenance process, pure Li is added after Mg is completely melted, wherein the third preset temperature is 700 to 720°C; Step (5), after the third preset temperature is maintained, the melt is refined to remove impurities, and then injected into a mold, cooled and solidified to obtain a molten aluminum-copper-lithium alloy.

5. An aluminum-copper-lithium alloy with adjustable recrystallization, characterized in that: The aluminum-copper-lithium alloy is prepared by the preparation method according to any one of claims 1 to 4.

6. A method for regulating the recrystallization of an aluminum-copper-lithium alloy, characterized in that: The method comprises the following steps: Step S10, providing an aluminum-copper-lithium alloy, wherein the aluminum-copper-lithium alloy is the aluminum-copper-lithium alloy according to claim 5; Step S20, performing a linear temperature increase homogenization heat treatment on the aluminum-copper-lithium alloy to place the Ag3Al particles in the aluminum-copper-lithium alloy in a precipitation state, thereby inhibiting the recrystallization of the aluminum-copper-lithium alloy.

7. The method for regulating recrystallization of aluminum-copper-lithium alloy according to claim 6, characterized in that: The linear temperature rise homogenization heat treatment includes: firstly heating the aluminum-copper-lithium alloy from room temperature to 440°C at a preset heating rate, then keeping the temperature at 440°C for 8 hours, then heating the aluminum-copper-lithium alloy from 440°C to 510°C at the preset heating rate, keeping the temperature for 24 hours, and then air cooling to room temperature.

8. The method for regulating recrystallization of aluminum-copper-lithium alloy according to claim 6 or 7, characterized in that: The method further comprises step S30 after step S20, wherein: Step S30, heat treating the aluminum-copper-lithium alloy obtained by the linear heating homogenization heat treatment in step S20 according to a preset heat treatment method, so that the Ag3Al precipitate particles in the aluminum-copper-lithium alloy are dissolved back into the matrix to promote the recrystallization of the aluminum-copper-lithium alloy.

9. The method for regulating recrystallization of aluminum-copper-lithium alloy according to claim 8, characterized in that: The preset heat treatment method of step S30 is specifically: heating the aluminum-copper-lithium alloy obtained by the linear temperature increase homogenization heat treatment of step S20 from room temperature to 470° C., and keeping it warm for 1 hour, and performing quenching treatment after the end of the heat preservation.

10. An aluminum-copper-lithium alloy, characterized in that: The aluminum-copper-lithium alloy of claim 5 is obtained by processing according to the control method of claim 6 or by processing according to the control method of claim 8.

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