High-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing and preparation method of high-strength and high-modulus rare earth aluminum alloy

Abstract

The invention discloses a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing and a preparation method of the high-strength and high-modulus rare earth aluminum alloy, and aims at high requirements on high strength and high modulus in the field of aerospace. According to the aluminum alloy, by reasonably designing the contents of Cu and Mg and microalloying elements Ce, La, Zr and Cr, the strength and modulus of the material are improved, the forming performance of additive manufacturing is improved, and the aluminum alloy is more suitable for additive manufacturing. Special powder suitable for additive manufacturing is prepared through vacuum melting and gas atomization, and the aluminum alloy is formed through the laser additive manufacturing technology. The result shows that the grain size of the alloy is obviously refined, the strength and modulus are greatly improved, and the development requirements of the aerospace field can be better met. The composition is reasonable in design, the preparation process is simple, the obtained product is excellent in performance, and large-scale industrial production and practical application are facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of rare earth aluminum alloy manufacturing, and specifically relates to a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing and a preparation method thereof. Background Art

[0002] Lightweight and high-strength aluminum alloys are key materials for the development of the aerospace field. Among them, Al-Cu-Mg aluminum alloys and Al-Zn-Mg aluminum alloys are widely used in the aerospace field, but the research and application of Al-Cu-Mg aluminum alloys are still far from enough. The extensive use of Al-Cu-Mg aluminum alloys is the development trend of the aerospace field in the future. However, the mechanical properties of Al-Cu-Mg aluminum alloys, such as strength and modulus, are poor and cannot fully meet the requirements of civil aircraft service. The Al-Cu-Mg-RE alloy system of rare earth aluminum alloys has experienced a transition from single alloy element modification to the current synergistic modification of multiple alloy elements, and has successively developed a variety of new aluminum alloys with RE as the main added element. As for the current status of the aluminum alloy industry, the application of elements such as Er and Cr in aluminum alloys is becoming increasingly mature, while the research and application of synergistic modification of rare earth elements such as Ce and La is not yet mature. In recent years, domestic and foreign studies have shown that adding 0.40-0.80% Ce and 0.20-0.60% La to Al-Cu-Mg aluminum alloys can significantly improve the strength and hardness of Al-Cu-Mg aluminum alloys.

[0003] At present, the traditional preparation methods of rare earth aluminum alloy materials are mainly directional solidification technology (metal mold casting method) and plastic forming technology (hot extrusion method). Both methods cannot directly process the target components, but require secondary processing or even multiple processing. In addition, the ability of traditional directional solidification technology to obtain higher temperature gradients and solidification rates has been difficult to improve; traditional plastic forming technology is difficult to achieve high-degree-of-freedom component forming, and the complexity and precision of formed components are far from low. In comparison, laser additive manufacturing can not only realize one-time direct forming of complex and precise components due to its forming principle of "model layering, layer-by-layer addition", but also achieves the manufacture of high-performance components by obtaining very high temperature gradients and extremely high cooling rates through the rapid movement of tiny molten pools. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and to provide a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing and a preparation method thereof, so as to solve the problem that the traditional aluminum alloy manufacturing method in the prior art is difficult to directly process the target component and requires secondary processing or even multiple processing. In order to achieve the above object, the present invention adopts the following technical solutions: A high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing comprises, by mass percentage, 4.00-5.00% Cu, 1.00-2.00% Mg, 0.40-0.80% Ce, 0.20-0.60% La, 0.1-0.25% Zr, 0.1-0.25% Cr, and the balance is Al.

[0005] A further improvement of the present invention is: Preferably, the high-strength and high-modulus rare earth aluminum alloy contains nanoscale L 12 (Al3Zr) precipitates.

[0006] A method for preparing the high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing comprises the following steps: Step 1, weighing and preparing raw materials according to the target composition, melting them in a vacuum melting furnace, and then pouring them to obtain an aluminum alloy ingot that meets the composition requirements; Step 2, preparing powder for laser additive manufacturing by using the aluminum alloy ingot obtained in step 1; Step 3, based on the powder obtained in step 2, printing a component by laser additive manufacturing; Step 4: subjecting the printed components to solid solution aging heat treatment to obtain a high-strength and high-modulus rare earth aluminum alloy.

[0007] Preferably, in step 1, the raw materials include pure aluminum, pure copper, pure magnesium ingots, Al-25Ce master alloy, Al-25La master alloy, Al-25Zr master alloy and Al-25Cr master alloy.

[0008] Preferably, in step 1, during the vacuum furnace smelting process, pure aluminum, pure copper and pure magnesium ingots are first added to the smelting furnace, and after they are completely melted, the temperature is continued to rise, and Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy and La particles wrapped in aluminum foil are added to start vacuum smelting.

[0009] Preferably, in step 1, after vacuum melting, casting is performed under argon protection conditions.

[0010] Preferably, in step 2, before preparing the powder, the oxide layer on the surface of the aluminum alloy ingot is removed.

[0011] Preferably, in step 3, during the laser additive manufacturing process, the laser energy density is 60-120 J / mm 3 .

[0012] Preferably, in step 4, the solution temperature is 250° C. and the holding time is 2 h.

[0013] Preferably, in step 4, the aging temperature is 150° C. and the holding time is 5 h.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing. In view of the high requirements for high strength and high modulus in the aerospace field, the strength and modulus of the material are improved by reasonably designing the Cu and Mg contents, as well as the micro-alloying elements Ce, La, Zr and Cr, and the additive manufacturing forming performance is improved, making it more suitable for additive manufacturing. Special powder suitable for additive manufacturing is prepared by vacuum melting and gas atomization, and the aluminum alloy is formed by laser additive manufacturing technology. The results show that the grain size of the alloy is significantly refined, and the strength and modulus are greatly improved, which can better meet the development requirements of the aerospace field. The alloy has excellent mechanical properties, especially taking into account the simultaneous improvement of strength and modulus, and has good additive manufacturing formability. The component design of the aluminum alloy of the present invention is reasonable, the preparation process is simple, the obtained product has excellent performance, and it is convenient for large-scale industrial production and practical application.

[0015] The present invention also discloses a method for preparing a high-strength and high-modulus rare earth aluminum alloy specially used for additive manufacturing. The method achieves a substantial improvement in the mechanical properties of the prepared rare earth aluminum alloy components, improves the process flow for preparing high-strength and high-modulus aluminum alloy components, can directly form high-precision and high-complexity components, and improves the traditional preparation methods and process flows of aluminum alloys.

[0016] The high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing and the preparation method thereof described in the present invention are expected to realize the whole-line design of "material-process-application" to meet the needs of today's high-tech fields such as aerospace - high strength and high modulus as the purpose, and use the synergistic effect of multiple alloys to design the composition of aluminum alloy materials, and further optimize the material composition through the principle of good adaptability of composition and process; in addition, a laser additive manufacturing method is proposed to prepare high-strength and high-modulus rare earth aluminum alloy components, realize the overall forming of complex and precise components in the fields of aerospace and so on, and greatly reduce production costs and production cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The metallographic diagram of the aluminum alloy sample obtained in Example 1; Figure 2 The metallographic image of the aluminum alloy sample obtained in Example 2; Figure 3 The metallographic diagram of the aluminum alloy sample obtained in Example 3; Figure 4 The metallographic image of the aluminum alloy sample obtained in Example 4; Figure 5 The metallographic diagram of the aluminum alloy sample obtained in Example 5; Figure 6The secondary L in the α-Al matrix of Al-Cu-Mg-Ce-La-Zr-Cr alloy formed by SLM was obtained after solution aging treatment. 12 (Al3Zr) phase characteristics. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with the accompanying drawings: 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.

[0019] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0020] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0021] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0022] The first aspect of the present invention discloses a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing. The high-strength and high-modulus aluminum alloy is based on an Al-Cu-Mg series high-strength aluminum alloy, with a rationally designed main component and the introduction of rare earth and trace elements. Specific mass percentage: 4.00-5.00% Cu, 1.00-2.00% Mg, 0.40-0.80% Ce, 0.20-0.60% La, 0.1-0.25% Zr, 0.1-0.25% Cr, the balance is Al, and also includes Fe and Si impurity elements, and the content of the impurity elements does not exceed 0.05%.

[0023] The high-strength and high-modulus rare earth aluminum alloy is obtained by regulating the alloy composition, utilizing the synergistic effect of multiple alloy elements and the principle of good adaptability between composition and process to rationally design the content of each element, and meeting the development needs of high-tech fields such as aerospace. Specifically, Ce can not only reduce the size of the eutectic component and the morphological changes of the intermetallic compound, refine the grain size, but also reduce the solidification temperature interval to reduce the formation of defects such as hot cracks, pores and segregation, thereby significantly improving the performance of the Al alloy; La can not only introduce fine thermally stable dispersed phases to pin dislocations and produce precipitation strengthening, but also increase the recrystallization temperature of the alloy. The key lies in the combined addition of Ce and La, which can form a finer precipitation phase; due to the fast diffusion rate of Ce and La in the aluminum matrix, segregation can be formed at the interface in advance to buy sufficient time for the diffusion of Zr and Cr, thereby reducing the interface energy to enhance the coarsening resistance and improve the strength of the alloy.

[0024] The second aspect of the present invention discloses a method for preparing a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing, comprising the following steps: Step 1, pouring ingots: using pure aluminum, pure copper, pure magnesium ingots and Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy as raw materials, calculating and proportioning according to the mass percentage of the aluminum alloy components, preheating, opening the smelting furnace, and when the furnace temperature reaches 400-450° C., adding the preheated pure aluminum, pure copper, and pure magnesium ingots into the smelting furnace, heating the temperature to 660-700° C. until all the ingots are completely melted; then continuously heating to 740-760° C., adding the preheated Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy and La particles wrapped in aluminum foil, stirring and salvaging the melt foam after all the alloys are melted; finally, after keeping warm at 720-740° C. for 10-20 minutes, casting in a metal mold under argon protection conditions to obtain an aluminum alloy ingot.

[0025] The purity of the pure aluminum, pure copper and pure magnesium ingots is above 99.9%, and the purity of the Al-25Ce master alloy, Al-25La master alloy, Al-25Zr master alloy and Al-25Cr master alloy is above 99.5%.

[0026] Step 2: prepare powder, mechanically remove the surface oxide layer of the aluminum alloy ingot obtained in step 1, and prepare powder for laser additive manufacturing by gas atomization.

[0027] The sphericity of the rare earth aluminum alloy powder obtained by the laser additive manufacturing method is above 99%.

[0028] Step 3, additive manufacturing: After the rare earth aluminum alloy powder obtained in step 2 is screened and dried, the component is manufactured using a laser additive manufacturing method. The specific laser additive manufacturing method is selective laser melting technology (SLM) or other laser additive manufacturing technologies.

[0029] The laser energy density of the laser additive manufacturing is 60-120 J / mm 3 In some specific examples, the laser energy density can be 60 J / mm 3 , 70 J / mm 3 、80 J / mm 3 , 90 J / mm 3 , 100 J / mm 3 , 110 J / mm 3 and 120 J / mm 3 Any one of .

[0030] Step 4, aging heat treatment, placing the rare earth aluminum alloy component obtained in step 3 in a heat treatment furnace for aging heat treatment, the solution temperature is 250°C, the holding time is 2h, the aging temperature is 150°C, and the holding time is 5h.

[0031] In the preparation method adopted by the present invention, the highly focused light beam and the rapid movement of the tiny molten pool in the additive manufacturing process make the solution have a very high temperature gradient and an extremely high cooling rate. The rapid solidification increases the supersaturation of Zr in the FCC-Al matrix, providing more Zr for precipitation, thereby increasing the nanoscale L 12 Volume fraction of (Al3Zr) precipitates to promote the formation of nanoscale L during aging treatment 12 The formation of (Al3Zr) precipitation significantly improves the tensile strength and creep resistance of the alloy. In addition, Ce and La may form a micro-fine grain structure different from that of traditional processing under the non-equilibrium solidification conditions of high cooling rate in additive manufacturing.

[0032] The following is further described in conjunction with specific embodiments.

[0033] Example 1 Step 1, pouring ingots: using pure aluminum, pure copper, pure magnesium ingots and Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy as raw materials, according to 4% Cu, 1% Mg, 0.4% Ce, 0.2% La, 0.1% Zr and 0.1% Cr, the balance is Al, preheating all raw materials, opening the smelting furnace, and when the furnace temperature reaches 420°C, pour the preheated pure aluminum, pure copper and pure magnesium ingots into the smelting furnace. The mixture was added into a smelting furnace and heated to 680°C until all the ingots were completely melted. The mixture was then heated to 750°C and preheated Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy and La particles wrapped in aluminum foil were added. After all the alloy ingots were completely melted, the melt foam was salvaged by stirring. The mixture was kept warm at 730°C for 15 minutes and cast into a metal mold under argon protection to obtain aluminum alloy ingots with uniform composition and no defects for powder preparation.

[0034] Step 2: prepare powder, mechanically remove the surface oxide layer of the aluminum alloy ingot obtained in step 1, and prepare powder for laser additive manufacturing by gas atomization.

[0035] Step 3, additive manufacturing: The rare earth aluminum alloy powder obtained in step 2 is sieved and dried, and then the components are manufactured by SLM. The laser energy density in the laser additive manufacturing process is 100 J / mm 3 .

[0036] Step 4, aging heat treatment, placing the rare earth aluminum alloy component obtained in step 3 in a heat treatment furnace for aging heat treatment, the solution temperature is 250°C, the holding time is 2h, the aging temperature is 150°C, and the holding time is 5h.

[0037] Example 2 Step 1, pouring ingots: using pure aluminum, pure copper, pure magnesium ingots and Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy as raw materials, in terms of mass percentage, according to 4.25% Cu, 1.25% Mg, 0.5% Ce, 0.3% La, 0.15% Zr and 0.15% Cr, the balance is Al, after preheating all the raw materials, start the smelting furnace, and when the furnace temperature reaches 420°C, pour the preheated pure aluminum and pure Copper and pure magnesium ingots are added to a smelting furnace and heated to 680°C until all the ingots are completely melted; then the temperature is continuously raised to 750°C, and preheated Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy and La particles wrapped in aluminum foil are added, and after all the alloy ingots are completely melted, the melt foam is stirred and salvaged; the temperature is kept at 730°C for 15 minutes, and metal mold casting is performed under argon protection conditions to obtain aluminum alloy ingots with uniform composition and no defects for powder preparation.

[0038] Step 2: prepare powder, mechanically remove the surface oxide layer of the aluminum alloy ingot obtained in step 1, and prepare powder for laser additive manufacturing by gas atomization.

[0039] Step 3, additive manufacturing: The rare earth aluminum alloy powder obtained in step 2 is sieved and dried, and then the components are manufactured by SLM. The laser energy density in the laser additive manufacturing process is 100 J / mm 3 .

[0040] Step 4, aging heat treatment, placing the rare earth aluminum alloy component obtained in step 3 in a heat treatment furnace for aging heat treatment, the solution temperature is 250°C, the holding time is 2h, the aging temperature is 150°C, and the holding time is 5h.

[0041] Example 3 Step 1, pouring ingots: using pure aluminum, pure copper, pure magnesium ingots and Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy as raw materials, in terms of mass percentage, according to 4.5% Cu, 1.5% Mg, 0.6% Ce, 0.4% La, 0.2% Zr and 0.2% Cr, the balance is Al, after preheating all the raw materials, start the smelting furnace, and when the furnace temperature reaches 420°C, pour the preheated pure aluminum, pure copper, Pure magnesium ingots are added into a smelting furnace and heated to 680°C until all the ingots are completely melted; then the temperature is continuously raised to 750°C, and preheated Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy and La particles wrapped in aluminum foil are added, and after all the alloy ingots are completely melted, the melt foam is stirred and salvaged; the temperature is kept at 730°C for 15 minutes, and metal mold casting is performed under argon protection conditions to obtain aluminum alloy ingots with uniform composition and no defects for powder preparation.

[0042] Step 2: prepare powder, mechanically remove the surface oxide layer of the aluminum alloy ingot obtained in step 1, and prepare powder for laser additive manufacturing by gas atomization.

[0043] Step 3, additive manufacturing: The rare earth aluminum alloy powder obtained in step 2 is sieved and dried, and then the components are manufactured by SLM. The laser energy density in the laser additive manufacturing process is 100 J / mm 3 .

[0044] Step 4, aging heat treatment, placing the rare earth aluminum alloy component obtained in step 3 in a heat treatment furnace for aging heat treatment, the solution temperature is 250°C, the holding time is 2h, the aging temperature is 150°C, and the holding time is 5h.

[0045] Example 4 Step 1, pouring ingots: using pure aluminum, pure copper, pure magnesium ingots and Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy as raw materials, according to the mass percentage, according to 4.75% Cu, 1.75% Mg, 0.7% Ce, 0.5% La, 0.25% Zr and 0.25% Cr, the balance is Al, all raw materials are preheated, the smelting furnace is turned on, and when the furnace temperature reaches 420°C, the preheated pure aluminum, pure copper and pure magnesium ingots are added. The mixture is put into a melting furnace and heated to 680°C until all the ingots are completely melted; then the temperature is continuously raised to 750°C, and preheated Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy and La particles wrapped in aluminum foil are added, and after all the alloy ingots are completely melted, the melt foam is stirred and salvaged; the mixture is kept warm at 730°C for 15 minutes, and finally, after appropriate heat preservation treatment, metal mold casting is carried out under argon protection conditions to obtain aluminum alloy ingots with uniform composition and no defects for powder preparation.

[0046] Step 2: prepare powder, mechanically remove the surface oxide layer of the aluminum alloy ingot obtained in step 1, and prepare powder for laser additive manufacturing by gas atomization.

[0047] Step 3, additive manufacturing: The rare earth aluminum alloy powder obtained in step 2 is sieved and dried, and then the components are manufactured by SLM. The laser energy density in the laser additive manufacturing process is 100 J / mm 3 .

[0048] Step 4, aging heat treatment, placing the rare earth aluminum alloy component obtained in step 3 in a heat treatment furnace for aging heat treatment, the solution temperature is 250°C, the holding time is 2h, the aging temperature is 150°C, and the holding time is 5h.

[0049] Example 5 Step 1, pouring ingots: using pure aluminum, pure copper, pure magnesium ingots and Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy as raw materials, according to 5% Cu, 2% Mg, 0.8% Ce, 0.6% La, 0.25% Zr and 0.25% Cr, the balance is Al, preheating all raw materials, opening the smelting furnace, and when the furnace temperature reaches 420°C, pour the preheated pure aluminum, pure copper and pure magnesium into the smelting furnace. The ingots are added into a melting furnace and heated to 680°C until all the ingots are completely melted; then the temperature is continuously raised to 750°C, and preheated Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy and La particles wrapped in aluminum foil are added, and after all the alloy ingots are completely melted, the melt foam is stirred and salvaged; the temperature is kept at 730°C for 15 minutes, and metal mold casting is performed under argon protection conditions to obtain aluminum alloy ingots with uniform composition and no defects for powder preparation.

[0050] Step 2: prepare powder, mechanically remove the surface oxide layer of the aluminum alloy ingot obtained in step 1, and prepare powder for laser additive manufacturing by gas atomization.

[0051] Step 3, additive manufacturing: The rare earth aluminum alloy powder obtained in step 2 is sieved and dried, and then the components are manufactured by SLM. The laser energy density in the laser additive manufacturing process is 100 J / mm 3 .

[0052] Step 4, aging heat treatment, placing the rare earth aluminum alloy component obtained in step 3 in a heat treatment furnace for aging heat treatment, the solution temperature is 250°C, the holding time is 2h, the aging temperature is 150°C, and the holding time is 5h.

[0053] In order to facilitate the strength test of aluminum alloy, the part model is set as a tensile specimen model.

[0054] The rare earth aluminum alloy samples obtained in the above examples were subjected to performance tests, including tensile strength test and hardness test.

[0055] Table 1 Performance test results

[0056] As can be seen from Table 1, the rare earth aluminum alloy of the present invention has a maximum hardness of 136 HIV, has a high modulus, and can meet the needs of practical applications. In aluminum alloys, hardness can be used as a measure of modulus, so the rare earth aluminum alloy of the present invention has the characteristics of high strength and high modulus.

[0057] from Figures 1 to 5It can be seen from the analysis that with the increase of alloying element content, the number of precipitated phase particles increases significantly and the distribution becomes more uniform. The formation of precipitated phase effectively improves the strength and modulus of the alloy through the precipitation strengthening mechanism. Figures 3 to 5 It can be observed that when the alloying element content is too high, the precipitated phase will coarsen or aggregate, thus affecting the uniformity of the structure. Combined with the performance data in Table 1, Figure 5 The alloy shown exhibits the highest hardness; this shows that, although excessive alloying element contents may lead to coarsening of the precipitates, within a certain range the mechanical properties can still be significantly optimized. Figure 6 The secondary L in the α-Al matrix of the SLM-formed Al-Cu-Mg-Ce-La-Zr-Cr alloy of Example 5 after solution aging treatment 12 (Al3Zr) phase characteristics.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing, characterized in that: Calculated by mass percentage, it includes 4.00-5.00% Cu, 1.00-2.00% Mg, 0.40-0.80% Ce, 0.20-0.60% La, 0.1-0.25% Zr, 0.1-0.25% Cr, and the balance is Al.

2. A high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing according to claim 1, characterized in that: The high-strength and high-modulus rare earth aluminum alloy contains nano-scale L 12 (Al3Zr) precipitates.

3. A method for preparing a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing as claimed in claim 1, characterized in that: The following steps are involved: Step 1, weighing and preparing raw materials according to the target composition, melting them in a vacuum melting furnace, and then pouring them to obtain an aluminum alloy ingot that meets the composition requirements; Step 2, preparing powder for laser additive manufacturing by using the aluminum alloy ingot obtained in step 1; Step 3, based on the powder obtained in step 2, printing a component by laser additive manufacturing; Step 4: subjecting the printed components to solid solution aging heat treatment to obtain a high-strength and high-modulus rare earth aluminum alloy.

4. The method for preparing a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing according to claim 3, characterized in that: In step 1, the raw materials include pure aluminum, pure copper, pure magnesium ingots, Al-25Ce master alloy, Al-25La master alloy, Al-25Zr master alloy and Al-25Cr master alloy.

5. The method for preparing a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing according to claim 3, characterized in that: In step 1, during the vacuum furnace smelting process, pure aluminum, pure copper and pure magnesium ingots are first added to the smelting furnace. After they are completely melted, the temperature is continued to rise, and Al-25Ce master alloy, Al-25Zr master alloy, Al-25Cr master alloy and La particles wrapped in aluminum foil are added to start vacuum smelting.

6. The method for preparing a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing according to claim 3, characterized in that: In step 1, after vacuum melting, casting is performed under argon protection conditions.

7. The method for preparing a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing according to claim 3, characterized in that: In step 2, before preparing the powder, the oxide layer on the surface of the aluminum alloy ingot is removed.

8. The method for preparing a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing according to claim 3, characterized in that: In step 3, during the laser additive manufacturing process, the laser energy density is 60-120 J / mm 3 .

9. The method for preparing a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing according to claim 2, characterized in that: In step 4, the solution temperature is 250°C and the holding time is 2h.

10. The method for preparing a high-strength and high-modulus rare earth aluminum alloy suitable for additive manufacturing according to claim 2, characterized in that: In step 4, the aging temperature is 150°C and the holding time is 5 hours.

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