Aluminum-copper-lithium alloy, method for preparing same, and method for controlling recrystallization thereof

Abstract

The application provides an aluminum-copper-lithium alloy and a preparation method and a recrystallization control method thereof. The preparation method comprises the following steps: melting industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy together at 700-800 DEG C, and adding silver particles, pure magnesium and pure lithium in sequence after the industrial-grade pure aluminum, the aluminum-copper alloy and the aluminum-zirconium alloy are completely melted, wherein the weight fraction of the industrial-grade pure aluminum is 21-23 parts, the weight fraction of the aluminum-copper alloy is 2.8-3.0 parts, the weight fraction of the aluminum-zirconium alloy is 0.02-0.03 parts, the weight fraction of the silver particles is 0.09-1 parts, the weight fraction of the pure magnesium is 0.12-0.14 parts, and the weight fraction of the pure lithium is 0.29-0.31 parts; after all the metals are completely melted, impurities are removed by refining, and then the aluminum-copper-lithium alloy is obtained by pouring into a mold, cooling and solidifying. The aluminum-copper-lithium alloy provided by the application can control the precipitation and dissolution of Ag3Al particles through a suitable heat treatment process, so as to realize the recrystallization control of the aluminum-copper-lithium alloy and meet the forming property and processability required by different components.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of alloy processing, and particularly relates to an aluminum-copper-lithium alloy and a preparation method and a recrystallization control method thereof. BACKGROUND

[0002] Compared with traditional aluminum alloys, the aluminum-copper-lithium alloy has a weight reduction of 10% to 20%, a rigidity increase of 15% to 20%, and meanwhile, maintains a high specific strength, excellent fatigue resistance and strong corrosion resistance, which makes the Al-Cu-Li alloy become an ideal structural material in the field of aerospace.

[0003] Although the as-cast Al-Cu-Li alloy can be shaped into complex parts, the as-cast Al-Cu-Li alloy has a relatively serious element segregation, a grain boundary segregation and a coarse second phase. The non-homogeneity of these microstructures reduces the performance, toughness and ductility of the alloy in the processes of extrusion, forging and rolling. The homogenization annealing heats the alloy to a high temperature and keeps the temperature for a long time, which can promote the dissolution of the coarse primary phase, reduce the segregation of solute elements, and meanwhile, the homogenization process makes the solute elements be redistributed and further promotes the precipitation of nanometer dispersed phases to refine the microstructure of the alloy, and the homogenization process can effectively solve the non-homogeneity problem of the as-cast alloy.

[0004] The micro-alloying technology plays an important role in improving the microstructure of the aluminum-copper-lithium alloy, for example, adding microelements such as Mn, Zr and Ce into the Al-Cu-Li alloy, and during the homogenization annealing process, uniform and dense Al 20 Cu2Mn3, Al3Zr and Al8Cu4Ce nanoscale precipitate particles are formed, and these precipitate particles, as a high-temperature stable phase, can pin the dislocation and subgrain boundary migration during the thermal deformation process, and often only play the role of recrystallization inhibition of the alloy, so as to be unable to form the recrystallization promotion purpose. Since the recrystallization can improve the formability and processability of the alloy, if the recrystallization of the microstructure of the alloy is inhibited, the formability of the complex cross-section part will be reduced, especially when the part with a high rib is shaped by the extrusion process, the recrystallization of the alloy is often inhibited, which makes the skin or rib not be completely shaped. Therefore, the recrystallization control of the Al-Cu-Li alloy becomes a problem to be solved. SUMMARY

[0005] The present application aims to provide a recrystallization-controllable aluminum-copper-lithium alloy, which, after linear heating homogenization heat treatment, makes Ag3Al particles in the aluminum-copper-lithium alloy in a precipitated state to inhibit recrystallization of the aluminum-copper-lithium alloy, and, after linear heating homogenization heat treatment and 470℃ heat preservation treatment, makes Ag3Al precipitate particles in the aluminum-copper-lithium alloy dissolve into the matrix to promote recrystallization of the aluminum-copper-lithium alloy, realizing that recrystallization of the aluminum-copper-lithium alloy can be controlled.

[0006] To achieve the above-mentioned purpose, the present application provides a preparation method of a recrystallization-controllable aluminum-copper-lithium alloy, which comprises: step 1), melting industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy together to 700-800℃, 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 fraction of the industrial-grade pure aluminum is 21-23 parts, the weight fraction of the aluminum-copper alloy is 2.8-3.0 parts, the weight fraction of the aluminum-zirconium alloy is 0.02-0.03 parts, the weight fraction of the silver particles is 0.09-1 part, the weight fraction of the pure magnesium is 0.12-0.14 part, and the weight fraction of the pure lithium is 0.29-0.31 part; and step 2), after all the metals are completely melted, removing impurities by refining, then pouring into a mold, and cooling and solidifying to obtain a melt-cast aluminum-copper-lithium alloy.

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

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

[0009] In a specific embodiment, the step 1) comprises: step (1), vacuum furnace preheating, wherein the preheating temperature is 300-400 DEG 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 the preheated vacuum furnace for melting, first increasing the temperature from the preheating temperature to a first preset temperature, and then keeping the temperature for 30 min, wherein the first preset temperature is 700-800 DEG C; step (3), after the keeping temperature at the first preset temperature is finished, all the metals in the graphite crucible are completely melted, silver particles are added to the melt, then the temperature of the vacuum furnace is set to a second preset temperature, and keeping the temperature for 10-20 min to completely melt the silver particles, wherein the second preset temperature is 700-750 DEG C; step (4), after the keeping temperature at the second preset temperature is finished, under the protection of argon, pure Mg is continuously added to the melt, keeping the temperature at a third preset temperature for 5-10 min under stirring, and during the keeping temperature, pure Li is added after the Mg is completely melted, wherein the third preset temperature is 700-720 DEG C; step (5), after the keeping temperature at the third preset temperature is finished, the melt is refined to remove impurities, then is poured into a mold, and after cooling and solidification, an as-cast aluminum-copper-lithium alloy is obtained.

[0010] The application further provides a recrystallization-controllable aluminum-copper-lithium alloy prepared by the preparation method.

[0011] The application further provides a method for controlling the recrystallization of an aluminum-copper-lithium alloy, comprising 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; and step S20, performing linear heating homogenization heat treatment on the aluminum-copper-lithium alloy, so that the Ag3Al particles in the aluminum-copper-lithium alloy are in a precipitated state to inhibit the recrystallization of the aluminum-copper-lithium alloy.

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

[0013] In a specific embodiment, the method further comprises a step S30 after step S20, wherein: step S30, performing heat treatment on the aluminum-copper-lithium alloy obtained by the linear heating homogenization heat treatment of step S20 according to a preset heat treatment mode, so that the Ag3Al precipitate particles in the aluminum-copper-lithium alloy dissolve into the matrix to promote the recrystallization of the aluminum-copper-lithium alloy.

[0014] In a specific embodiment, the preset heat treatment mode of step S30 is specifically: the aluminum-copper-lithium alloy obtained by the linear temperature increasing homogenization heat treatment of step S20 is heated from room temperature to 470 DEG C, and is kept for 1h, and then is quenched after the keeping.

[0015] The application also provides the aluminum-copper-lithium alloy obtained by the regulation method.

[0016] The application has at least the following beneficial effects:

[0017] I. The application provides a preparation method of a recrystallization-regulated aluminum-copper-lithium alloy, which comprises the following steps: step 1), melting industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy together at 700-800 DEG C, and adding silver particles, pure magnesium and pure lithium in sequence after the complete melting of the industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy, wherein the weight fraction of the industrial-grade pure aluminum is 21-23 parts, the weight fraction of the aluminum-copper alloy is 2.8-3.0 parts, the weight fraction of the aluminum-zirconium alloy is 0.02-0.03 parts, the weight fraction of the silver particles is 0.09-1 part, the weight fraction of the pure magnesium is 0.12-0.14 part, and the weight fraction of the pure lithium is 0.29-0.31 part; step 2), after the complete melting of all the metals, removing impurities by refining, and then pouring into a mold, and obtaining a melt-cast aluminum-copper-lithium alloy by cooling and solidification; in this way, a new type of aluminum-copper-lithium alloy is melt-cast based on the provided preparation method, and the precipitation and dissolution of Ag3Al particles can be regulated by a suitable heat treatment process, so that the recrystallization of the aluminum-copper-lithium alloy is regulated, and the formability and processability required by different components are met.

[0018] II. The aluminum-copper-lithium alloy is subjected to linear temperature increasing homogenization heat treatment, and the Ag3Al particles in the aluminum-copper-lithium alloy are in a precipitated state, so that the recrystallization of the aluminum-copper-lithium alloy is inhibited, and the aluminum-copper-lithium alloy is suitable for forming components with a simple cross section; the aluminum-copper-lithium alloy obtained by the linear temperature increasing homogenization heat treatment is subjected to 470 DEG C / 1h heat treatment, and the Ag3Al precipitate particles in the aluminum-copper-lithium alloy dissolve into the matrix, so that the recrystallization of the aluminum-copper-lithium alloy is promoted, and the aluminum-copper-lithium alloy is suitable for forming skin components with high ribs and the like by an extrusion process; in this way, the recrystallization performance of the alloy is controllable, the alloy can meet the forming and processing requirements of components of different sizes, and it has great significance for promoting the more extensive engineering application of Al-Cu-Li alloy. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The step flow chart of the regulation method of the recrystallization of the aluminum-copper-lithium alloy provided by the application;

[0020] Figure 2 The compression and sampling schematic diagram corresponding to example 2 and example 3 of the application;

[0021] Figure 3 Fig. 2 is a diagram of the recrystallization structure characterization results of the cylindrical sample A provided in Embodiment 2 of the present application after thermal compression;

[0022] Figure 4 Fig. 3 is a TEM diagram of the sample 1 prepared in Embodiment 2 of the present application;

[0023] Figure 5 Fig. 4 is a diagram of the recrystallization structure characterization results of the cylindrical sample B provided in Embodiment 3 of the present application after thermal compression. DETAILED DESCRIPTION

[0024] The present application is described in detail below in conjunction with the accompanying drawings and embodiments, but can be implemented in various different ways according to the limitations and coverage of the claims.

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

[0026] In order to improve the mechanical properties of the alloy material and prolong the service life of the material, the prior art discloses that the recrystallization performance of the aluminum-copper-lithium alloy is inhibited by adding inhibitors and optimizing the processing technology, and the recrystallization of the alloy cannot be promoted after the recrystallization of the alloy is inhibited, which will affect the formability and processability of the alloy, such as forming a part with a high rib on the skin by an extrusion process. The recrystallization of the alloy is inhibited, which will often make the skin or rib not completely formed. The present application improves the formula of the existing aluminum alloy, provides a new type of aluminum-copper-lithium alloy, the alloy can realize the recrystallization control of the alloy by controlling the precipitation and dissolution of Ag3Al particles through a suitable heat treatment process, so as to meet different forming requirements.

[0027] The present application provides a preparation method of a recrystallization-controllable aluminum-copper-lithium alloy, the preparation method comprises the following steps:

[0028] Step 1), melt industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy together at 700-800℃, and after the industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy are completely melted, add silver particles, pure magnesium and pure lithium in sequence, wherein the weight fraction of the industrial-grade pure aluminum is 21-23 parts, the weight fraction of the aluminum-copper alloy is 2.8-3.0 parts, the weight fraction of the aluminum-zirconium alloy is 0.02-0.03 parts, the weight fraction of the silver particles is 0.09-1 part, the weight fraction of the pure magnesium is 0.12-0.14 part, and the weight fraction of the pure lithium is 0.29-0.31 part.

[0029] Preferably, after the industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy are completely melted, the silver particles, pure magnesium and pure lithium are added in sequence, specifically, the pure magnesium is added after the silver particles are completely melted, and the pure lithium is added 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℃, and the preheating time is 20-30min.

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

[0033] Step (3), after the holding at the first preset temperature ends, all the metals in the graphite crucible have completely melted, silver particles are added to the melt, then the temperature of the vacuum furnace is set to a second preset temperature, and holding for 10-20min to completely melt the silver particles, wherein the second preset temperature is 700-750℃.

[0034] Step (4), after the holding at the second preset temperature ends, under the protection of argon, pure Mg is continuously added to the melt, and holding for 5-10min at a third preset temperature under stirring, and during the holding, pure Li is added after the Mg is completely melted, wherein the third preset temperature is 700-720℃.

[0035] Step (5), after the holding at the third preset temperature ends, the melt is refined to remove impurities, then poured into a mold, and cooled and solidified to obtain the aluminum-copper-lithium alloy in a cast state.

[0036] Preferably, the temperature increasing rate from the preheating temperature to the first preset temperature is 200℃ / h.

[0037] Preferably, the second preset temperature and the third preset temperature are the same, 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℃, and the second preset temperature and the third preset temperature are 720℃.

[0039] Step 2), after all the metals are completely melted, refining to remove impurities, then pouring into a mold, and cooled and solidified to obtain the aluminum-copper-lithium alloy in a cast state.

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

[0041] The application further provides a recrystallization-controllable aluminum-copper-lithium alloy prepared by the preparation method.

[0042] Referring to Figure 1 The application further provides a recrystallization-controllable aluminum-copper-lithium alloy prepared by the preparation method.

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

[0044] The aluminum-copper-lithium alloy is prepared by the preparation method described above, and will not be described here again.

[0045] Step S20, performing linear temperature increasing homogenization heat treatment on the aluminum-copper-lithium alloy, so that Ag3Al particles in the aluminum-copper-lithium alloy are in a precipitated state, thereby inhibiting recrystallization of the aluminum-copper-lithium alloy.

[0046] Preferably, the linear temperature increasing homogenization heat treatment comprises: first increasing the temperature of the aluminum-copper-lithium alloy from room temperature to 440 DEG C at a preset temperature increasing rate, then keeping the temperature at 440 DEG C for 8 hours, then increasing the temperature of the aluminum-copper-lithium alloy from 440 DEG C to 510 DEG C at the preset temperature increasing rate, and continuing to keep the temperature for 24 hours, and then air cooling to room temperature.

[0047] In the application, the linear temperature increasing homogenization heat treatment can improve the heterogeneous problems of the microstructure of the as-cast Al-Cu-Li alloy, such as element segregation, grain boundary segregation, and coarse second phase.

[0048] Preferably, the preset temperature increasing rate is 25 DEG C / h.

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

[0050] Step S30, performing heat treatment on the aluminum-copper-lithium alloy obtained by the linear temperature increasing homogenization heat treatment of step S20 according to a preset heat treatment mode, so that Ag3Al precipitate particles in the aluminum-copper-lithium alloy dissolve into the matrix, thereby promoting recrystallization of the aluminum-copper-lithium alloy.

[0051] Preferably, the preset heat treatment mode of step S30 is specifically that the aluminum-copper-lithium alloy obtained by the linear temperature increasing homogenization heat treatment of step S20 is increased from room temperature to 470 DEG C and kept for 1 hour, and then quenched after the end of the keeping.

[0052] The application further provides an aluminum-copper-lithium alloy obtained by performing linear temperature increasing homogenization heat treatment on a recrystallization-controllable aluminum-copper-lithium alloy.

[0053] Preferably, the linear temperature increasing homogenization heat treatment comprises: firstly increasing the temperature of the aluminum-copper-lithium alloy from room temperature to 440 DEG C at a preset temperature increasing rate, then keeping the temperature at 440 DEG C for 8 hours, then increasing the temperature of the aluminum-copper-lithium alloy from 440 DEG C to 510 DEG C at the preset temperature increasing rate, and then keeping the temperature for 24 hours, and then air cooling to room temperature.

[0054] It can be understood that the aluminum-copper-lithium alloy herein is a recrystallization-inhibited aluminum-copper-lithium alloy.

[0055] The application further provides an aluminum-copper-lithium alloy, which is obtained by sequentially subjecting a recrystallization-controllable aluminum-copper-lithium alloy to linear temperature increasing homogenization heat treatment and preset heat treatment.

[0056] Preferably, the linear temperature increasing homogenization heat treatment comprises: firstly increasing the temperature of the aluminum-copper-lithium alloy from room temperature to 440 DEG C at a preset temperature increasing rate, then keeping the temperature at 440 DEG C for 8 hours, then increasing the temperature of the aluminum-copper-lithium alloy from 440 DEG C to 510 DEG C at the preset temperature increasing rate, and then keeping the temperature for 24 hours, and then air cooling to room temperature; and the preset heat treatment specifically comprises: increasing the temperature of the aluminum-copper-lithium alloy obtained by the linear temperature increasing homogenization heat treatment from room temperature to 470 DEG C, keeping the temperature for 1 hour, and then quenching after the keeping.

[0057] It can be understood that the aluminum-copper-lithium alloy herein is a recrystallization-promoted aluminum-copper-lithium alloy.

[0058] Example 1

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

[0060] Step 1, preheat the vacuum furnace, specifically: set the loading temperature of the vacuum furnace to 400 DEG C, and the preheating time to 20 min.

[0061] Step 2, place the to-be-melted melt of 22.5 kg of industrial pure aluminum, 2.85 kg of Al-50wt% Cu alloy and 0.026 kg of Al-10wt% Zr alloy in a graphite crucible, and then transfer the graphite crucible to the preheated vacuum furnace, set the temperature of the vacuum furnace to 750 DEG C, and keep the temperature for 30 min.

[0062] Step 3, after keeping the temperature at 750 DEG C for 30 min, the melt in the graphite crucible has been completely melted, 0.10 kg of silver particles are added to the melt, the temperature of the vacuum furnace is set to 720 DEG C, and the temperature is kept for 20 min to completely melt the silver particles.

[0063] Step 4, after keeping the temperature at 720 DEG C for 20 min, 0.13 kg of pure Mg is then added under the protection of argon, and the temperature is kept at 720 DEG C for 10 min under stirring, and during the keeping, 0.3 kg of pure Li is added after the complete melting of the Mg.

[0064] Step 5, after holding at 720℃ for 10 min, the melt was refined to remove impurities, and then the melt was poured into a preheated cylindrical metal mold coated with boron nitride, and solidified by cooling to obtain an as-cast aluminum lithium copper alloy.

[0065] The chemical composition of the aluminum lithium copper alloy was measured by inductively coupled plasma emission spectrometer (ICP) element analysis: 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%, the balance being aluminum, represented 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] Regulation method for inhibiting recrystallization of aluminum lithium copper alloy

[0068] The Al-5.47Cu-1.19Li-0.51Mg-0.38Ag alloy was subjected to linear heating homogenization heat treatment, and the heat treatment process was as follows: heating from room temperature to 440℃ at a rate of 25℃ / h, holding at 440℃ for 8h, then heating from 440℃ to 510℃ at a rate of 25℃ / h, and then holding for 24h, then taking the sample out of the heating furnace, and air cooling the sample 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 8mm and a length of 12mm was taken from the center of the alloy after linear heating heat treatment (sample 1), and a Gleeble 3180 thermal simulator was used to heat compress the cylindrical sample A, and the heat compression conditions were as follows: the cylindrical sample A was heated to 450℃, the strain rate was 0.15s -1 , and the cylindrical sample A was compressed to 70% along the length direction of the cylindrical sample. In order to prevent further grain growth after compression, the cylindrical sample A was immediately taken out of the thermal simulator and then placed in a container with water medium. Then the center of the compressed cylindrical sample A was sampled by wire cutting, and the sampling area was as shown in Figure 2As shown, firstly, the removed sample was coarsely ground to make the two end faces of the sample flat, one of which was pasted on a counterweight, and the other was sequentially ground with 800-grit sandpaper, 1500-grit sandpaper, and 2000-grit sandpaper, 400-grit sandpaper, and then the red velvet polishing cloth was replaced to continue grinding the sample end face with the abrasive paste with particle sizes of 2.5 μm, 1.5 μm, and 0.5 μm, respectively, until the sample end face was ground to a mirror state. Finally, the porous neoprene polishing cloth was replaced to continue suspending the mirror sample with the silica polishing liquid with a particle size of 0.05 μm, and the suspending time was 3 h. Finally, the sample was washed clean for electron backscatter diffraction (EBSD) characterization experiments.

[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°, as shown in Figure 3 After compression of the cylindrical sample A, the RD is the compression direction, and the grains are elongated along the TD direction. The black filled area is a complete recrystallization structure, and the recrystallization fraction of the sample is 2.3%. The low recrystallization fraction indicates that the recrystallization of the alloy is significantly inhibited after linear heating heat treatment.

[0071] Further transmission electron microscopy (TEM) observation was performed on the linearly heated sample, as shown in Figure 4 It can be seen from Figure 4 that Ag3Al precipitate particles can precipitate along the grain boundary and inside the grain. These dense Ag3Al precipitate particles can pin dislocations and subgrain boundaries during subsequent thermal deformation, serving to inhibit recrystallization.

[0072] According to the Ag-Al phase diagram, μ phase (Ag3Al) will dissolve above 440℃, and μ phase (Ag3Al) will dissolve at 450℃. Therefore, Ag3Al is not precipitated during the holding stage of linear heating heat treatment, but is precipitated during air cooling to room temperature. Long holding time causes supersaturation of solute, which provides conditions for the precipitation of Ag3Al during the cooling stage.

[0073] Example 3

[0074] Method for promoting recrystallization of aluminum-copper-lithium alloy

[0075] The aluminum-copper-lithium alloy prepared in Example 1 was treated according to the linear heating homogenization heat treatment process provided in Example 2, and then was subjected to 470℃ / 1h heat treatment and finally quenched to obtain sample 2.

[0076] In order to characterize the dynamic recrystallization fraction of the alloy, the sample 2 is 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 is quickly subjected to hot compression, and the hot compression condition is that the sample is heated to 450 DEG C, the strain rate is about 0.15 s -1 , and the cylindrical sample B is compressed to 70% along the length direction of the cylindrical sample. The center region of the compressed sample (which can be referred to as shown in Figure 2 ) is taken, and the cut sample is again coarsely ground so that the two end faces of the sample are flat, one of which is pasted on a counterweight, and the other end face is sequentially ground by 800 mesh sandpaper, 1500 mesh sandpaper and 2000 mesh sandpaper, 400 mesh sandpaper, and then the red velvet polishing cloth is replaced to continue grinding the end face of the sample by sequentially matching the abrasive paste with a particle size of 2.5 μm, 1.5 μm and 0.5 μm, until the end face of the sample is ground to a mirror state. Finally, the porous neoprene polishing cloth is replaced to continue suspending the mirror sample by matching the silica polishing liquid with a particle size of 0.05 μm, and the suspending time is 3 h, and finally the sample is washed clean for electron backscatter diffraction (EBSD) characterization experiment.

[0077] The recrystallization of the sample subjected to linear temperature rise and 470 DEG C / 1 h heat treatment is analyzed by EBSD post-processing software TSL OIM software, and the dynamic recrystallization structure of the sample is characterized by setting the grain orientation spread value (GOS) <2 DEG, as shown in Figure 5 . After the compression of the cylindrical sample B, the RD is the compression direction, and the grains are elongated along the TD direction. The black filled area is a complete recrystallization 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 temperature rise and 470 DEG C / 1 h heat treatment.

[0078] The Al-Cu-Li alloy prepared by the preparation method provided by the present application is subjected to linear temperature rise homogenization heat treatment, and the recrystallization of the Al-Cu-Li alloy is inhibited, and the Al-Cu-Li alloy is subjected to linear temperature rise homogenization heat treatment and 470 DEG C / 1 h heat treatment, and the recrystallization of the Al-Cu-Li alloy is promoted, so that the recrystallization of the alloy can be controlled, and the alloy can meet the forming and processing requirements of different components, which has great significance for promoting the more extensive engineering application of the Al-Cu-Li alloy.

[0079] The above is a further detailed description of the present application in combination with specific preferred embodiments, and the specific implementation of the present application cannot be limited to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, without departing from the concept of the present application, a number of simple deductions and substitutions can be made, which should be regarded as falling within the protection scope of the present application.

Claims

1. A method of controlling recrystallization of an aluminum-lithium-copper alloy, characterized by, The method comprises the following steps: Step S10, providing an aluminum-copper-lithium alloy, a preparation method of the aluminum-copper-lithium alloy comprising: Step 1), melting industrial-grade pure aluminum, aluminum-copper alloy and aluminum-zirconium alloy together at 700-800°C, and adding silver particles, pure magnesium and pure lithium in sequence after the industrial-grade pure aluminum, the aluminum-copper alloy and the aluminum-zirconium alloy are completely melted, wherein the weight fraction of the industrial-grade pure aluminum is 21-23 parts, the weight fraction of the aluminum-copper alloy is 2.8-3.0 parts, the weight fraction of the aluminum-zirconium alloy is 0.02-0.03 parts, the weight fraction of the silver particles is 0.09-1 part, the weight fraction of the pure magnesium is 0.12-0.14 parts, and the weight fraction of the pure lithium is 0.29-0.31 parts; Step 2), after all the metals are completely melted, impurities are removed by refining, and then the aluminum-copper-lithium alloy is poured into a mold, cooled and solidified to obtain a cast aluminum-copper-lithium alloy; Step S20, linear temperature increasing homogenization heat treatment is performed on the aluminum-copper-lithium alloy to make Ag3Al particles in the aluminum-copper-lithium alloy in a precipitated state to inhibit recrystallization of the aluminum-copper-lithium alloy; Step S30, the aluminum-copper-lithium alloy obtained by the linear temperature increasing homogenization heat treatment of step S20 is heat treated in a preset heat treatment mode to make Ag3Al precipitate particles in the aluminum-copper-lithium alloy dissolve into the matrix to promote recrystallization of the aluminum-copper-lithium alloy; The linear temperature increasing homogenization heat treatment comprises: first, 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, and continuing to keep the temperature for 24 hours, and then air cooling to room temperature; The preset heat treatment mode of step S30 is specifically that the aluminum-copper-lithium alloy obtained by the linear temperature increasing homogenization heat treatment of step S20 is heated from room temperature to 470°C and kept for 1 hour, and then quenched after the keeping.

2. The method of claim 1, wherein the aluminum-lithium-copper alloy is an alloy having a composition of 1.8-2.2 wt% Li, 0.8-1.2 wt% Cu, and the balance Al. The mass fraction of copper in the aluminum-copper alloy is 50% based on the total weight of the aluminum-copper alloy; and the mass fraction of zirconium in the aluminum-zirconium alloy is 10% based on the total weight of the aluminum-zirconium alloy.

3. The method for controlling the recrystallization of aluminum-copper-lithium alloy according to claim 1 or 2, characterized in that, The silver particles are added after the industrial-grade pure aluminum, the aluminum-copper alloy and the aluminum-zirconium alloy are completely melted, the pure magnesium is added after the silver particles are completely melted, and the pure lithium is added after the pure magnesium is completely melted.

4. The method of claim 3, wherein the aluminum-lithium-copper alloy is an alloy having a composition of 1.8-2.2 wt% Li, 0.8-1.2 wt% Cu, and the balance Al. 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 the industrial-grade pure aluminum, the aluminum-copper alloy and the aluminum-zirconium alloy in a graphite crucible and transferring them to the preheated vacuum furnace for melting, first heating from the preheating temperature to a first preset temperature, and then keeping the temperature for 30 min, wherein the first preset temperature is 700-800°C; Step (3), after the end of the first preset temperature holding, all the metals in the graphite crucible are completely melted, silver particles are added to the melt, then the temperature of the vacuum furnace is set to a second preset temperature, and the temperature is held for 10-20 min to completely melt the silver particles, wherein the second preset temperature is 700-750 DEG C; Step (4), after the end of the second preset temperature holding, pure Mg is continuously added to the melt under the protection of argon, and the temperature is continuously held at a third preset temperature for 5-10 min under stirring, and pure Li is added after the Mg is completely melted during the holding process, wherein the third preset temperature is 700-720 DEG C; Step (5), after the end of the third preset temperature holding, the melt is refined to remove impurities, then poured into a mold, and cooled and solidified to obtain a cast aluminum-copper-lithium alloy.

5. An aluminum lithium copper alloy characterized in that, The aluminum-copper-lithium alloy is treated according to the regulation method of any one of claims 1 to 4. The aluminum-copper-lithium alloy is treated according to the regulation method of any one of claims 1 to 4.

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