High-hardness aluminum alloy and preparation method thereof

Abstract

The invention discloses a high-hardness aluminum alloy and a preparation method thereof, and belongs to the technical field of aluminum alloys. The high-hardness aluminum alloy is prepared from the following components in percentage by weight: 0.1 percent to 0.2 percent of Si, 0.1 percent to 0.3 percent of Mn, 0.02 percent to 0.05 percent of Zn, 0.02 percent to 0.05 percent of Mg, 0.3 percent to 0.5 percent of Cu, 0.02 percent to 0.05 percent of Cr, 0.05 percent to 0.2 percent of graphene, 2 percent to 3 percent of TiB2 and the balance of Al. The high-hardness aluminum alloy has excellent hardness, toughness and corrosion resistance, is long in service life, can meet the requirements of spaceflight and aviation on material reliability, and also meets the requirement of light weight.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloys, and particularly relates to a high-hardness aluminum alloy and a preparation method thereof. Background Art

[0002] Aluminum alloy is an alloy with a certain amount of other alloying elements added to aluminum. It has low density but relatively high strength, close to or exceeding high-quality steel, good plasticity, can be processed into various profiles, has good casting performance and plastic processing performance, good electrical conductivity, thermal conductivity and weldability, can be used as a structural material, and has a wide range of applications in aerospace, aviation, transportation, construction, electromechanical, light chemicals and daily necessities. At present, although the existing aluminum alloy has a certain mechanical strength, its own toughness is relatively poor, hardness and corrosion resistance are relatively insufficient, it is easy to break, and the anti-fatigue effect is poor.

[0003] Patent CN116179909B discloses a high-hardness aluminum alloy and its production process. The high-hardness aluminum alloy comprises the following components: Si: 0.35-0.45%, Ti: 0.07-0.12%, Mn: 0.45-0.68%, Zn: 7.3-8.9%, Mg: 3.0-3.5%, B: 0.06-0.18%, Cd: 0.25-0.42%, Cu: 2.6-3.3%, Cr: 0.22-0.30%, Li: 0.05-0.1%, Ni: 0.58-0.75%, Mo: 0.06-0.12%, V: 0.1-0.15%, rare earth elements: 0.2-0.28%, inorganic powder: 0.68-0.85%, metal nitride: 0.23-0.38%, metal additives: 0.05-0.1%, and the rest are Al and unavoidable impurities. However, this invention adds a lot of rare earth elements and requires nitriding treatment, which makes it difficult to match its cost and performance.

[0004] Patent CN108359852B discloses a graphene-enhanced aluminum-based composite material and a preparation method thereof, wherein a blank is prepared by hot pressing and sintering a mixed powder of a certain proportion of silicon, copper, magnesium, titanium, boron, graphene and aluminum for a long time after ball milling, and then the blank is heat treated and forged and annealed for 5-10 times to obtain a graphene-enhanced aluminum-based composite material. The graphene-enhanced aluminum-based composite material prepared by this process has a high hardness, but the bonding strength between graphene and the aluminum matrix is ​​low, and the comprehensive performance of the aluminum alloy material is poor. Summary of the invention

[0005] In view of the deficiencies in the prior art, an object of the present invention is to provide a high-hardness aluminum alloy and a preparation method thereof, wherein the high-hardness aluminum alloy has excellent hardness, toughness and corrosion resistance and a long service life.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a high hardness aluminum alloy is provided. The high hardness aluminum alloy components include, by weight percentage: Si: 0.1-0.2%, Mn: 0.1-0.3%, Zn: 0.02-0.05%, Mg: 0.02-0.05%, Cu: 0.3-0.5%, Cr: 0.02-0.05%, graphene: 0.05-0.2%, TiB2: 2-3%, and the balance is Al.

[0007] In the present invention, the graphene is a graphene nanosheet with an average thickness of 1-5nm and an average sheet diameter of 1-3µm. In the aluminum alloy system of the present invention, the size of the graphene nanosheet is critical to the regulation of the internal structure of the alloy. The inventor selects the graphene nanosheet of the above-mentioned specific size and a specific preparation method, so that the prepared aluminum alloy forms a perfect sandwich structure, so that the aluminum alloy material as a whole shows a significant synergistic improvement effect of strength and plasticity.

[0008] In the present invention, the TiB2 is nano TiB2 particles generated in situ. In the present invention, the average diameter of the nano TiB2 particles is 50-100nm. The present invention, through a specific preparation method, especially the control of hot rolling deformation treatment, breaks up the large-sized TiB2 in the alloy to a certain extent, realizes the regulation of the size of the TiB2 particles generated in situ in the alloy material, so that the TiB2 particles can better play the pinning effect, and form a perfect sandwich structure reinforcement layer with the graphene nanosheets. Compared with the method of directly adding TiB2 nanoparticles, the method of the present invention can make the TiB2 particles more evenly dispersed in the system, reduce the structural defects of the aluminum alloy, improve the interface bonding strength between the graphene nanosheets and the aluminum matrix, and make the aluminum alloy material as a whole show a significant synergistic improvement effect of strength and plasticity.

[0009] In the present invention, the graphene is a copper-coated graphene nanosheet. The present invention can effectively improve the wettability and bonding strength between the graphene nanosheet and the alloy matrix by copper-coating the graphene nanosheet, improve the integrity of the graphene nanosheet, and help the graphene nanosheet to be better dispersed in the alloy structure, so as to better play a synergistic effect.

[0010] In the present invention, in the high-hardness aluminum alloy, the weight percentage of the graphene is 0.05-0.2%, preferably 0.1%. In the high-hardness aluminum alloy, the weight percentage of the TiB2 is 2-3%, preferably 2.5%. The inventors found that in the aluminum alloy system of the present invention, the content of graphene and TiB2 has a key influence on the hardness and toughness of the alloy. If the content of graphene is high, graphene is prone to agglomeration, which increases the structural defects in the system, thereby reducing the performance of the alloy; if the content of graphene is low, the layered structure of the alloy is not well developed, and the synergistic effect of graphene and TiB2 is not obvious. At the same time, a high content of TiB2 will also lead to obvious agglomeration, thereby reducing the performance of the alloy; if the content of TiB2 is low, the synergistic pinning of the Al2Cu particles generated on the graphene surface and the dispersed TiB2 particles is significantly reduced, so that the graphene is easily pulled out under the action of external force, thereby greatly improving the stress concentration inside the aluminum alloy and reducing the toughness and strength of the alloy material.

[0011] According to another aspect of the present invention, there is also provided a method for preparing the above-mentioned high hardness aluminum alloy, comprising the following steps: (1) Surface pretreatment of graphene, stirring and dispersing the pretreated graphene in a chemical copper plating solution, slowly dropping a formaldehyde solution, and reacting at 60-65° C. for 30-40 hours to obtain surface copper-coated graphene nanosheets; mixing and ball-milling the surface copper-coated graphene nanosheets and aluminum powder to obtain a first mixed powder; (2) Potassium fluoroborate and potassium fluorotitanate are mixed in proportion and evenly mixed, and preheated to 180-220° C. to obtain a second mixed powder; (3) putting raw materials containing Al, Si, Mn, Zn, Mg, Cu and Cr into a smelting furnace for smelting, adding the second mixed powder, reacting for 20-30 minutes, cooling to 650-700° C., adding the first mixed powder, stirring, and casting to obtain a cast aluminum alloy; (4) The cast aluminum alloy is homogenized, and then subjected to three hot rolling deformation treatments, solution treatment and aging treatment in sequence to obtain the high-hardness aluminum alloy.

[0012] In the present invention, in step (1), the graphene is surface pretreated, the pretreated graphene is stirred and dispersed in a chemical copper plating solution, formaldehyde solution is slowly added, and the reaction is carried out at 60-65°C for 30-40h to obtain surface copper-coated graphene nanosheets; the surface copper-coated graphene nanosheets and aluminum powder are mixed and ball-milled to obtain a first mixed powder. In the present invention, in step (1), the surface pretreatment is specifically: graphene is ultrasonically dispersed in deionized water, hydrochloric acid solution and stannous chloride dihydrate are added, stirred at room temperature for 50-60min, filtered, washed, added to the activation solution, stirred at room temperature for 50-60min, filtered, washed to neutral, and dried. Preferably, the hydrochloric acid solution is a hydrochloric acid solution with a mass concentration of 37wt%. In the present invention, in step (1), the chemical copper plating solution comprises: 15-20g / L copper sulfate pentahydrate, 18-20g / L potassium sodium tartrate, 20-25g / L disodium ethylenediaminetetraacetate and 10-15ml / L formaldehyde. In the present invention, in step (1), the mass ratio of the surface copper-coated graphene nanosheets and the aluminum powder is 1:2-3. The present invention controls the mass ratio of the surface copper-coated graphene nanosheets and the aluminum powder for ball milling, and the ball milling effect is better. In the present invention, in step (1), the activation solution is a mixed solution of silver nitrate and ammonia water, preferably, the ammonia water is a 27wt% ammonia water solution; more preferably, the mass ratio of the silver nitrate and ammonia water is 1:1-2.

[0013] In the present invention, in step (2), potassium fluoroborate and potassium fluorotitanate are mixed in proportion and evenly mixed, and preheated to 180-220° C. to obtain a second mixed powder. Preferably, the molar ratio of potassium fluoroborate to potassium fluorotitanate is 2-2.1:1.

[0014] In the present invention, in step (3), raw materials containing Al, Si, Mn, Zn, Mg, Cu and Cr are put into a smelting furnace for smelting, the second mixed powder is added, reacted for 20-30 minutes, cooled to 650-700°C, the first mixed powder is added, stirred, and cast to obtain a cast aluminum alloy. Preferably, the smelting temperature is 850-900°C.

[0015] In the present invention, in step (4), the cast aluminum alloy is homogenized, and then three hot rolling deformation treatments, solution treatment and aging treatment are performed in sequence to obtain the high-hardness aluminum alloy. In the present invention, in step (4), the three hot rolling deformation treatments are specifically: the first hot rolling deformation treatment is performed at 450-460°C for 1-2h, the second hot rolling deformation treatment is performed at 460-470°C for 1-2h, and the third hot rolling deformation treatment is performed at 470-480°C for 1-2h. Preferably, the total deformation is controlled to be 75-82%. In the present invention, the temperature of the homogenization treatment is 550-560°C and the time is 18-20h. In the present invention, the temperature of the solution treatment is 520-550°C and the time is 2-3h. In the present invention, the temperature of the aging treatment is 170-180°C and the time is 3-4h. The present invention can reduce the structural defects of aluminum alloy, improve the distribution of nanoparticles, and enhance the interface bonding strength between graphene nanosheets and aluminum matrix through specific three-step hot rolling deformation treatment, so that the randomly distributed GNPs and TiB2 nanoparticles in the cast aluminum alloy are arranged along the hot rolling direction to form a non-continuous layered structure, thereby making the aluminum alloy material as a whole show a significant synergistic improvement effect of strength and plasticity.

[0016] The inventors found that by using the method of casting in situ generated nano TiB2 particles and adding a specific amount of graphene, a certain amount of two-dimensional and zero-dimensional modified materials are simultaneously introduced into the aluminum alloy system. On this basis, the structure of the aluminum alloy is transformed into a discontinuous layered structure through three hot rolling deformation treatments, in which the TiB2 nanoparticles dispersed on both sides of the graphene nanosheets form a reinforcing layer of a sandwich structure with the graphene nanosheets, and other dispersed TiB2 nanoparticles play a role of dispersion strengthening, stabilizing the alloy lattice, so that the aluminum alloy material as a whole shows a significant synergistic improvement effect of strength and plasticity, improves corrosion resistance, and effectively prolongs the service life of aluminum alloy products to a certain extent.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention adopts a specific mass content of graphene, TiB2 and other alloy elements for combination, and a specific amount of in-situ generated TiB2 nanoparticles and graphene form a sandwich structure reinforcement layer, which realizes good structural regulation of aluminum alloy materials, thereby synergistically enhancing the hardness of the aluminum alloy and effectively improving the toughness of the aluminum alloy.

[0018] (2) The present invention simultaneously introduces a certain amount of two-dimensional and zero-dimensional modified materials into the aluminum alloy system by using a method of casting in situ generated nano-TiB2 particles and adding a specific amount of graphene. On this basis, the structure of the aluminum alloy is transformed into a discontinuous layered structure through three hot rolling deformation treatments, in which the TiB2 nanoparticles dispersed on both sides of the graphene nanosheets form a reinforcing layer of a sandwich structure with the graphene nanosheets, and other dispersed TiB2 nanoparticles play a role of dispersion strengthening and stabilize the alloy lattice, so that the aluminum alloy material as a whole shows a significant synergistic improvement effect of strength and plasticity, improves corrosion resistance, and effectively prolongs the service life of aluminum alloy products to a certain extent.

[0019] (3) The preparation method of the present invention is simple and convenient, the product performance is stable, and it is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is a photo of the surface corrosion degree of the flat tube made of high-hardness aluminum alloy in Example 1 of the present application; Figure 2 This is a photograph of the surface corrosion degree of the flat tube made of high-hardness aluminum alloy in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0023] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0024] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, improvements and equivalents of the methods and materials described in the present invention can be included in the scope limited by the claims.

[0025] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0026] The present invention provides a high-hardness aluminum alloy. The high-hardness aluminum alloy comprises, by weight percentage, components of Si: 0.1-0.2%, Mn: 0.1-0.3%, Zn: 0.02-0.05%, Mg: 0.02-0.05%, Cu: 0.3-0.5%, Cr: 0.02-0.05%, graphene: 0.05-0.2%, TiB2: 2-3%, and the balance is Al.

[0027] In the present invention, the graphene is a graphene nanosheet with an average thickness of 1-5nm and an average sheet diameter of 1-3µm.

[0028] In the present invention, the TiB2 is nano-TiB2 particles generated in situ.

[0029] In the present invention, the graphene is a graphene nanosheet with surface covered with copper.

[0030] In the present invention, the average diameter of the nano-TiB2 particles is 50-100 nm.

[0031] According to another aspect of the present invention, there is also provided a method for preparing the above-mentioned high hardness aluminum alloy, comprising the following steps: (1) Surface pretreatment of graphene, stirring and dispersing the pretreated graphene in a chemical copper plating solution, slowly dropping a formaldehyde solution, and reacting at 60-65° C. for 30-40 hours to obtain surface copper-coated graphene nanosheets; mixing and ball-milling the surface copper-coated graphene nanosheets and aluminum powder to obtain a first mixed powder; (2) Potassium fluoroborate and potassium fluorotitanate are mixed in proportion and evenly mixed, and preheated to 180-220° C. to obtain a second mixed powder; (3) putting raw materials containing Al, Si, Mn, Zn, Mg, Cu and Cr into a smelting furnace for smelting, adding the second mixed powder, reacting for 20-30 minutes, cooling to 650-700° C., adding the first mixed powder, stirring, and casting to obtain a cast aluminum alloy; (4) The cast aluminum alloy is subjected to a homogenization treatment and three hot rolling deformation treatments in sequence, and then cooled to obtain the high-hardness aluminum alloy.

[0032] In the present invention, in step (1), the surface pretreatment is specifically as follows: ultrasonically dispersing graphene in deionized water, adding hydrochloric acid solution and stannous chloride dihydrate, stirring at room temperature for 50-60 minutes, filtering, washing, adding to the activation solution, stirring at room temperature for 50-60 minutes, filtering, washing until neutral, and drying.

[0033] In the present invention, in step (1), the chemical copper plating solution comprises: 15-20 g / L copper sulfate pentahydrate, 18-20 g / L potassium sodium tartrate, 20-25 g / L disodium ethylenediaminetetraacetate and 10-15 ml / L formaldehyde.

[0034] In the present invention, in step (3), the smelting temperature is 850-900°C.

[0035] In the present invention, in step (4), the three hot rolling deformation treatments are specifically: a first hot rolling deformation treatment is performed at 450-460°C for 1-2h, a second hot rolling deformation treatment is performed at 460-470°C for 1-2h, and a third hot rolling deformation treatment is performed at 470-480°C for 1-2h.

[0036] The present invention will be described in detail below by way of examples. It should be understood that the following examples are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention. Among them, Example 1 is the best embodiment of the present invention.

[0037] The chemical additives used in the examples and comparative examples of the present invention are all commercially available, and their specific information is as follows: Graphene: graphene nanosheets with an average thickness of 1-5 nm and an average sheet diameter of 1-3 µm, purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.; Al-Cr: aluminum-chromium alloy, purchased from Jinzhou Haixin Metal Materials Co., Ltd.; copper sulfate pentahydrate, potassium sodium tartrate, disodium ethylenediaminetetraacetic acid, formaldehyde, hydrochloric acid, stannous chloride dihydrate, high-purity aluminum, manganese powder, magnesium powder, copper powder, silicon powder and zinc powder: the above raw materials were all purchased from Aladdin Reagent Co., Ltd.

[0038] Example 1 The high-hardness aluminum alloy described in this embodiment includes, by weight percentage, the following components: Si: 0.1%, Mn: 0.2%, Zn: 0.04%, Mg: 0.03%, Cu: 0.4%, Cr: 0.02%, graphene: 0.1%, TiB2: 2.5%, and the balance is Al.

[0039] The method for preparing the high-hardness aluminum alloy comprises the following steps: (1) Surface pretreatment of graphene, stirring and dispersing the pretreated graphene in a chemical copper plating solution, slowly adding formaldehyde solution, reacting at 60°C for 40h, and obtaining surface copper-coated graphene nanosheets; mixing and ball-milling the surface copper-coated graphene nanosheets and aluminum powder at a mass ratio of 1:2 to obtain a first mixed powder; wherein the surface pretreatment is specifically as follows: ultrasonically dispersing 1g of graphene in deionized water, adding 25mL of a hydrochloric acid solution with a mass concentration of 37wt% and 15g of stannous chloride dihydrate, stirring at room temperature for 50min, filtering, washing, and then adding to an activation solution containing 5g of silver nitrate and 6mL of ammonia water, stirring at room temperature for 50min, filtering, washing until neutral, and drying. The chemical copper plating solution includes: 20g / L copper sulfate pentahydrate, 20g / L potassium sodium tartrate, 25g / L disodium ethylenediaminetetraacetic acid, and 15ml / L formaldehyde.

[0040] (2) Potassium fluoroborate and potassium fluorotitanate in a molar ratio of 2.1:1 are mixed in proportion and uniformly mixed, and preheated to 220° C. to obtain a second mixed powder; (3) High-purity aluminum, Al-Cr, manganese powder, magnesium powder, copper powder, silicon powder and zinc powder are mixed according to the proportion, put into a smelting furnace for smelting at a smelting temperature of 850° C., add the second mixed powder, react for 30 minutes, cool to 650° C., add the first mixed powder, stir, and cast to obtain a cast aluminum alloy; (4) The cast aluminum alloy is subjected to homogenization treatment and three hot rolling deformation treatments in sequence, the total deformation amount is controlled to be 82%, and the alloy is cooled to obtain the high-hardness aluminum alloy. The three hot rolling deformation treatments are as follows: the first hot rolling deformation treatment is carried out at 450°C for 1 hour, the second hot rolling deformation treatment is carried out at 470°C for 2 hours, and the third hot rolling deformation treatment is carried out at 480°C for 2 hours.

[0041] Example 2 The high-hardness aluminum alloy described in this embodiment includes, by weight percentage, the following components: Si: 0.2%, Mn: 0.1%, Zn: 0.05%, Mg: 0.05%, Cu: 0.3%, Cr: 0.05%, graphene: 0.2%, TiB2: 3%, and the balance is Al.

[0042] The method for preparing the high-hardness aluminum alloy comprises the following steps: (1) Surface pretreatment of graphene, stirring and dispersing the pretreated graphene in a chemical copper plating solution, slowly adding formaldehyde solution, reacting at 65°C for 30 hours, and obtaining surface copper-coated graphene nanosheets; mixing and ball-milling the surface copper-coated graphene nanosheets and aluminum powder at a mass ratio of 1:3 to obtain a first mixed powder; wherein the surface pretreatment is specifically as follows: ultrasonically dispersing 1g of graphene in deionized water, adding 25mL of a hydrochloric acid solution with a mass concentration of 37wt% and 15g of stannous chloride dihydrate, stirring at room temperature for 60min, filtering, washing, and then adding to an activation solution containing 5g of silver nitrate and 6mL of ammonia water, stirring at room temperature for 60min, filtering, washing until neutral, and drying. The chemical copper plating solution includes: 15g / L copper sulfate pentahydrate, 18g / L potassium sodium tartrate, 20g / L disodium ethylenediaminetetraacetic acid, and 10ml / L formaldehyde.

[0043] (2) Potassium fluoroborate and potassium fluorotitanate in a molar ratio of 2:1 are mixed in proportion and uniformly, and preheated to 220° C. to obtain a second mixed powder; (3) High-purity aluminum, Al-Cr, manganese powder, magnesium powder, copper powder, silicon powder and zinc powder are mixed according to the proportion, put into a smelting furnace for smelting at a smelting temperature of 900° C., add the second mixed powder, react for 20 minutes, cool to 700° C., add the first mixed powder, stir, and cast to obtain a cast aluminum alloy; (4) The cast aluminum alloy is subjected to homogenization treatment and three hot rolling deformation treatments in sequence, the total deformation amount is controlled to be 75%, and the alloy is cooled to obtain the high-hardness aluminum alloy. The three hot rolling deformation treatments are as follows: the first hot rolling deformation treatment is carried out at 450°C for 2 hours, the second hot rolling deformation treatment is carried out at 460°C for 1 hour, and the third hot rolling deformation treatment is carried out at 470°C for 1 hour.

[0044] Example 3 The high-hardness aluminum alloy described in this embodiment includes, by weight percentage, the following components: Si: 0.1%, Mn: 0.3%, Zn: 0.02%, Mg: 0.02%, Cu: 0.5%, Cr: 0.04%, graphene: 0.05%, TiB2: 2%, and the balance is Al.

[0045] The method for preparing the high-hardness aluminum alloy comprises the following steps: (1) Surface pretreatment of graphene, stirring and dispersing the pretreated graphene in a chemical copper plating solution, slowly adding formaldehyde solution, reacting at 60°C for 35h, and obtaining surface copper-coated graphene nanosheets; mixing and ball-milling the surface copper-coated graphene nanosheets and aluminum powder at a mass ratio of 1:2 to obtain a first mixed powder; wherein the surface pretreatment is specifically as follows: ultrasonically dispersing 1g of graphene in deionized water, adding 25mL of a hydrochloric acid solution with a mass concentration of 37wt% and 15g of stannous chloride dihydrate, stirring at room temperature for 50min, filtering, washing, and then adding to an activation solution containing 5g of silver nitrate and 6mL of ammonia water, stirring at room temperature for 60min, filtering, washing until neutral, and drying. The chemical copper plating solution includes: 15g / L copper sulfate pentahydrate, 20g / L potassium sodium tartrate, 20g / L disodium ethylenediaminetetraacetic acid, and 15ml / L formaldehyde.

[0046] (2) Potassium fluoroborate and potassium fluorotitanate in a molar ratio of 2.1:1 are mixed in proportion and uniformly mixed, and preheated to 200° C. to obtain a second mixed powder; (3) High-purity aluminum, Al-Cr, manganese powder, magnesium powder, copper powder, silicon powder and zinc powder are mixed according to the proportion, put into a smelting furnace for smelting at a smelting temperature of 890° C., add the second mixed powder, react for 25 minutes, cool to 700° C., add the first mixed powder, stir, and cast to obtain a cast aluminum alloy; (4) The cast aluminum alloy is subjected to homogenization treatment and three hot rolling deformation treatments in sequence, the total deformation amount is controlled to be 80%, and the alloy is cooled to obtain the high-hardness aluminum alloy. The three hot rolling deformation treatments are as follows: the first hot rolling deformation treatment is carried out at 455°C for 2 hours, the second hot rolling deformation treatment is carried out at 465°C for 1 hour, and the third hot rolling deformation treatment is carried out at 475°C for 2 hours.

[0047] Example 4 The high-hardness aluminum alloy described in this embodiment includes, by weight percentage, the following components: Si: 0.2%, Mn: 0.3%, Zn: 0.05%, Mg: 0.05%, Cu: 0.3%, Cr: 0.02%, graphene: 0.2%, TiB2: 2%, and the balance is Al.

[0048] The method for preparing the high-hardness aluminum alloy comprises the following steps: (1) Surface pretreatment of graphene, stirring and dispersing the pretreated graphene in a chemical copper plating solution, slowly adding formaldehyde solution, reacting at 60°C for 30h, and obtaining surface copper-coated graphene nanosheets; mixing and ball-milling the surface copper-coated graphene nanosheets and aluminum powder at a mass ratio of 1:2 to obtain a first mixed powder; wherein the surface pretreatment is specifically as follows: ultrasonically dispersing 1g of graphene in deionized water, adding 25mL of a hydrochloric acid solution with a mass concentration of 37wt% and 15g of stannous chloride dihydrate, stirring at room temperature for 50min, filtering, washing, and then adding to an activation solution containing 5g of silver nitrate and 6mL of ammonia water, stirring at room temperature for 50min, filtering, washing until neutral, and drying. The chemical copper plating solution includes: 20g / L copper sulfate pentahydrate, 18g / L potassium sodium tartrate, 22g / L disodium ethylenediaminetetraacetic acid, and 10ml / L formaldehyde.

[0049] (2) Potassium fluoroborate and potassium fluorotitanate in a molar ratio of 2:1 are mixed in proportion and uniformly, and preheated to 220° C. to obtain a second mixed powder; (3) High-purity aluminum, Al-Cr, manganese powder, magnesium powder, copper powder, silicon powder and zinc powder are mixed according to the proportion, put into a smelting furnace for smelting at a smelting temperature of 850° C., add the second mixed powder, react for 30 minutes, cool to 650° C., add the first mixed powder, stir, and cast to obtain a cast aluminum alloy; (4) The cast aluminum alloy is subjected to homogenization treatment and three hot rolling deformation treatments in sequence, the total deformation amount is controlled to be 78%, and the alloy is cooled to obtain the high-hardness aluminum alloy. The three hot rolling deformation treatments are as follows: the first hot rolling deformation treatment is carried out at 460°C for 1 hour, the second hot rolling deformation treatment is carried out at 470°C for 2 hours, and the third hot rolling deformation treatment is carried out at 480°C for 2 hours.

[0050] Comparative Example 1 The preparation method of the high-hardness aluminum alloy described in this comparative example is the same as that of Example 1, except that the mass percentage of graphene is 0.5%.

[0051] Comparative Example 2 The preparation method of the high hardness aluminum alloy described in this comparative example is the same as that of Example 1, the only difference being that the mass percentage of TiB2 is 5%.

[0052] Comparative Example 3 The preparation method of the high-hardness aluminum alloy described in this comparative example is the same as that of Example 1, except that the TiB2 is non-in-situ generated TiB2 particles. The specific preparation method of the aluminum alloy comprises the following steps: (1) Surface pretreatment of graphene, stirring and dispersing the pretreated graphene in a chemical copper plating solution, slowly adding formaldehyde solution, reacting at 60°C for 30h, and obtaining surface copper-coated graphene nanosheets; mixing and ball-milling the surface copper-coated graphene nanosheets and aluminum powder at a mass ratio of 1:2 to obtain a first mixed powder; wherein the surface pretreatment is specifically as follows: ultrasonically dispersing 1g of graphene in deionized water, adding 25mL of a hydrochloric acid solution with a mass concentration of 37wt% and 15g of stannous chloride dihydrate, stirring at room temperature for 50min, filtering, washing, and then adding to an activation solution containing 5g of silver nitrate and 6mL of ammonia water, stirring at room temperature for 50min, filtering, washing until neutral, and drying. The chemical copper plating solution includes: 20g / L copper sulfate pentahydrate, 20g / L potassium sodium tartrate, 25g / L disodium ethylenediaminetetraacetic acid, and 15ml / L formaldehyde.

[0053] (2) High-purity aluminum, Al-Cr, manganese powder, magnesium powder, copper powder, silicon powder and zinc powder are mixed according to the proportion, put into a smelting furnace for smelting at a smelting temperature of 850° C., TiB2 nanoparticles (average diameter of 100 nm) are added, react for 30 minutes, cool to 650° C., add the first mixed powder, stir, and cast to obtain a cast aluminum alloy; (3) The cast aluminum alloy is subjected to homogenization treatment and three hot rolling deformation treatments in sequence, the total deformation amount is controlled to be 78%, and the alloy is cooled to obtain the high-hardness aluminum alloy. The three hot rolling deformation treatments are as follows: the first hot rolling deformation treatment is carried out at 460°C for 1 hour, the second hot rolling deformation treatment is carried out at 470°C for 2 hours, and the third hot rolling deformation treatment is carried out at 480°C for 2 hours.

[0054] Comparative Example 4 The preparation method of the high hardness aluminum alloy described in this comparative example is the same as that of Example 1, except that the hot rolling deformation treatment is a hot rolling deformation treatment at 480° C. for 5 hours.

[0055] Comparative Example 5 The preparation method of the high hardness aluminum alloy described in this comparative example is the same as that of Example 1, the only difference being that the hot rolling deformation treatment is performed at 450° C. for 3 h for the first time and at 480° C. for 2 h for the second time.

[0056] Comparative Example 6 The method for preparing the high-hardness aluminum alloy described in this comparative example is the same as that in Example 1, except that the graphene surface is not subjected to pretreatment and copper coating, that is, step (1) is omitted.

[0057] Performance Testing The microstructure and mechanical properties of the high hardness aluminum alloys described in Examples 1-4 and Comparative Examples 1-6 were tested according to the following methods. The specific results are shown in Table 1.

[0058] TiB2 size: obtained through the SEM image of the microstructure of aluminum alloy material; Tensile strength, yield strength and elongation: tested in accordance with standard GB / T228.1-2021; Hardness: Tested in accordance with standard GB / T230.1-2018.

[0059] Table 1 Performance data of high hardness aluminum alloys in Examples 1-4 and Comparative Examples 1-6 .

[0060] It can be seen from Table 1 that the high-hardness aluminum alloy described in Examples 1-4 of the present invention has both excellent hardness and toughness, indicating that the specific mass content of graphene, TiB2 and other alloying elements are matched to achieve good structural regulation of the aluminum alloy material, thereby synergistically enhancing the hardness of the aluminum alloy and effectively improving the toughness of the aluminum alloy. It can be seen from Example 1 and Comparative Examples 1 and 2 that the graphene content in Comparative Example 1 is relatively high, and the content of TiB2 in Comparative Example 2 is relatively high, and the toughness of the material is reduced, indicating that the agglomeration phenomenon produces stress concentration, thereby reducing the toughness of the material. It can be seen from Example 1 and Comparative Example 3 that the TiB2 in Comparative Example 3 is non-in-situ generated TiB2 particles, and the toughness of the material is also significantly reduced. It can be seen from Example 1 and Comparative Examples 4 and 5 that the hot rolling deformation treatment in Comparative Examples 4 and 5 is different, and the toughness of the material is also deteriorated, indicating that the hot rolling deformation treatment is very critical for the regulation of the internal structure of the alloy. It can be seen from Example 1 and Comparative Example 6 that the graphene in Comparative Example 6 is not copper-coated, and the tensile strength and toughness of the material are also significantly reduced, indicating that the interface bonding strength of graphene and the aluminum alloy matrix is ​​weak, thereby damaging the mechanical properties of the material.

[0061] Corrosion resistance test: The aluminum alloys in Examples 1-4 and Comparative Examples 1-6 were made into flat tubes (length 200 mm) and subjected to a cyclic acidic seawater test (SWAAT) according to standard ASTM G85 for a total test time of 1960 h. During the test, photos were taken and the corrosion conditions were observed and recorded. After 1960 h, 1 MPa nitrogen was introduced at a constant pressure for 60 s to observe whether the flat tubes leaked. The specific results are shown in Table 2 and Figure 1-2 shown.

[0062] Table 2 Corrosion resistance data of high hardness aluminum alloys in Examples 1-4 and Comparative Examples 1-6 .

[0063] It can be seen from Table 2 that the flat tubes made of high-hardness aluminum alloys described in Examples 1-4 of the present invention have excellent corrosion resistance and no leakage after 1960 hours. Figure 1It can be seen that the flat tube made of high-hardness aluminum alloy in Example 1 only began to slightly increase in flaky corrosion after 1920 hours, indicating that the material has excellent corrosion resistance. It can be seen from Example 1 and Comparative Examples 1 and 2 that the graphene content in Comparative Example 1 is relatively high, and the TiB2 content in Comparative Example 2 is relatively high. Both materials began to suffer large-scale corrosion after 480 hours, and corrosion cascade phenomenon began to occur after 960 hours, indicating that the corrosion resistance of Comparative Examples 1 and 2 is significantly reduced. Figure 2 It can be clearly observed that the flat tube in Comparative Example 1 showed large-area corrosion at 480h, and the degree of corrosion became more serious with the increase of time. It can be seen from Example 1 and Comparative Example 3 that the TiB2 in Comparative Example 3 is TiB2 particles generated non-in situ, and the corrosion resistance of the material is also significantly reduced. It can be seen from Example 1 and Comparative Examples 4 and 5 that the hot rolling deformation treatments in Comparative Examples 4 and 5 are different, and the corrosion resistance of the material also deteriorates, indicating that the hot rolling deformation treatment is very critical for the regulation of the internal structure of the alloy. It can be seen from Example 1 and Comparative Example 6 that the graphene in Comparative Example 6 has no copper coating treatment, and the corrosion resistance of the material is also significantly reduced, indicating that the interface bonding strength between graphene and the aluminum alloy matrix is ​​weak, the reinforcing layer of the sandwich structure is not well developed, and the internal structure of the alloy material is poorly regulated, thereby damaging the corrosion resistance of the material.

[0064] It can be seen that the present invention adopts graphene, TiB2 and other alloy elements with a specific mass content to cooperate, and a specific amount of in-situ generated TiB2 nanoparticles and graphene form a sandwich structure reinforcement layer, which realizes good structural regulation of aluminum alloy materials, thereby synergistically enhancing the hardness of aluminum alloys and effectively improving the toughness of aluminum alloys, and reducing the stress corrosion cracking sensitivity of aluminum alloys. In addition, the present invention simultaneously introduces a certain amount of two-dimensional and zero-dimensional modified materials into the aluminum alloy system by using a method of casting in-situ generated nano TiB2 particles and adding specific graphene. On this basis, the structure of the aluminum alloy is transformed into a non-continuous layered structure through three hot rolling deformation treatments, wherein the TiB2 nanoparticles dispersed on both sides of the graphene nanosheets form a sandwich structure reinforcement layer with the graphene nanosheets, and other dispersed TiB2 nanoparticles play a role of dispersion strengthening, so that the aluminum alloy material as a whole shows a significant synergistic improvement effect of strength and plasticity, and effectively prolongs the service life of aluminum alloy products to a certain extent.

[0065] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A high hardness aluminum alloy, characterized in that: In terms of weight percentage, the high hardness aluminum alloy composition Including: Si: 0.1-0.2%, Mn: 0.1-0.3%, Zn: 0.02-0.05%, Mg: 0.02-0.05%, Cu: 0.3-0.5%, Cr: 0.02-0.05%, graphene: 0.05-0.2%, TiB2: 2-3%, and the balance is Al.

2. The high hardness aluminum alloy according to claim 1, characterized in that: The graphene is a graphene nanosheet with an average thickness of 1-5nm and an average sheet diameter of 1-3µm.

3. The high hardness aluminum alloy according to claim 1, characterized in that: The TiB2 is nano-TiB2 particles generated in situ.

4. The high hardness aluminum alloy according to claim 1, characterized in that: The graphene is a graphene nanosheet with copper coated on the surface.

5. The high hardness aluminum alloy according to claim 3, characterized in that: The average diameter of the nano-TiB2 particles is 50-100 nm.

6. A method for preparing the high hardness aluminum alloy according to any one of claims 1 to 5, characterized in that: The steps include: (1) Surface pretreatment of graphene, stirring and dispersing the pretreated graphene in a chemical copper plating solution, slowly dropping a formaldehyde solution, and reacting at 60-65° C. for 30-40 hours to obtain surface copper-coated graphene nanosheets; mixing and ball-milling the surface copper-coated graphene nanosheets and aluminum powder to obtain a first mixed powder; (2) Potassium fluoroborate and potassium fluorotitanate are mixed in proportion and evenly mixed, and preheated to 180-220° C. to obtain a second mixed powder; (3) putting raw materials containing Al, Si, Mn, Zn, Mg, Cu and Cr into a smelting furnace for smelting, adding the second mixed powder, reacting for 20-30 minutes, cooling to 650-700° C., adding the first mixed powder, stirring, and casting to obtain a cast aluminum alloy; (4) The cast aluminum alloy is subjected to a homogenization treatment and three hot rolling deformation treatments in sequence, and then cooled to obtain the high-hardness aluminum alloy.

7. The method for preparing a high-hardness aluminum alloy according to claim 6, characterized in that: In step (1), the surface pretreatment is specifically as follows: ultrasonically dispersing graphene in deionized water, adding hydrochloric acid solution and stannous chloride dihydrate, stirring at room temperature for 50-60 minutes, filtering, washing, adding to the activation solution, stirring at room temperature for 50-60 minutes, filtering, washing until neutral, and drying.

8. The method for preparing a high-hardness aluminum alloy according to claim 6, characterized in that: In step (1), the chemical copper plating solution comprises: 15-20 g / L copper sulfate pentahydrate, 18-20 g / L potassium sodium tartrate, 20-25 g / L disodium ethylenediaminetetraacetate and 10-15 ml / L formaldehyde.

9. The method for preparing a high-hardness aluminum alloy according to claim 6, characterized in that: In step (3), the smelting temperature is 850-900°C.

10. The method for preparing a high-hardness aluminum alloy according to claim 6, characterized in that: In step (4), the three hot rolling deformation treatments are specifically: the first hot rolling deformation treatment is performed at 450-460°C for 1-2h, the second hot rolling deformation treatment is performed at 460-470°C for 1-2h, and the third hot rolling deformation treatment is performed at 470-480°C for 1-2h.

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