Preparation method of Mg2Si in-situ synthesis aluminum-based composite material
By using La or Ce rare earth elements and Al-Sr-RE composite deteriorating agent in aluminum-based composite materials, the problem of poor Mg2Si morphology in traditional casting processes is solved, and the plasticity and mechanical properties of the material are significantly improved. , reduces production costs.
Patent Information
- Application Number
- CN202411085855.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-08
- Publication Date
- 2024-12-10
AI Technical Summary
Under the traditional casting process, the poor morphology of Mg2Si leads to limited plasticity and application performance of Al-Mg2Si alloys. The existing improvement methods have high prices for rare earth elements or have failed to effectively refine eutectic Mg2Si.
La or Ce as rare earth elements, combined with Al-Sr-RE composite deteriorating agent, the primary and eutectic Mg2Si is significantly refined through the fusion and casting process, and its morphology and distribution are improved, forming a high plasticity in situ self-generating aluminum matrix. Composite material.
The morphology and distribution of Mg2Si is significantly improved, the plasticity of Al-Mg2Si composite material is improved, the production cost is reduced, the crystal size and shape is achieved, and the mechanical properties of the material are improved.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of materials, and in particular relates to a method for preparing a Mg2Si in-situ self-generated aluminum-based composite material. Background Art
[0002] Al-Mg-Si casting alloys are widely used in the fields of automobiles, communications, electronics, aerospace, etc. due to their good fluidity, high specific strength, low thermal expansion coefficient, good material casting performance and processing performance. Mg and Si can form Mg2Si intermetallic compounds, which have the characteristics of low density, high elastic modulus, high hardness and good wear resistance. They can be used as reinforcements to prepare Al-Mg2Si composite materials, which are expected to be used in the fields of aviation, aerospace and automobiles.
[0003] However, under the traditional casting process, primary Mg2Si mainly presents coarse dendrites, while eutectic Mg2Si consists of coupled eutectics composed of multi-branched flakes. Coarse dendrites and coupled eutectics of flakes can easily cause stress concentration, leading to the generation and expansion of crack sources, resulting in the elongation of the alloy usually not exceeding 2%. Therefore, improving the morphology, size and distribution of Mg2Si is of great significance to the plasticity and application of Al-Mg2Si alloys.
[0004] Modification and refinement treatment is one of the effective methods to improve the structure and performance of alloys, and it has the advantages of simple operation, low cost, and significant effect, and is the most commonly used in the industry. In recent years, people have explored the improvement of Mg2Si morphology and alloy plasticity, and have achieved certain results. For example, CN109112368A discloses a Sc-containing cast hypoeutectic Al-Mg2Si alloy and its production method. By adding 0.15% to 0.35% Sc, the eutectic Mg2Si is transformed from a coarse Chinese character shape to a fine fiber shape, and the morphology of the primary α-Al is transformed from dendrites to spherical crystals. The mechanical properties, especially the plasticity, are greatly improved, and the tensile strength and elongation of the alloy are increased by 21.41% and 86.11% respectively. CN111118355A provides a rare earth element erbium modified casting hypoeutectic Al-Mg2Si alloy and its preparation method. Through the modification of the rare earth element Er on the alloy, the eutectic Mg2Si is transformed from a coarse Chinese character shape to a fine fiber shape, and the primary α-Al phase is refined at the same time, and the tensile strength and elongation of the alloy are increased by 27.50% and 82.41% respectively. CN111411246A discloses a method for ultrasonic treatment and Bi composite refinement of hypoeutectic Al-Mg2Si alloy structure. By adding Bi to improve the morphology of eutectic Mg2Si, a morphology characterized by coral, fiber and granular is formed, and the alloy casting defects, Bi segregation and primary aluminum are eliminated by ultrasonic treatment, thereby improving the comprehensive mechanical properties of the hypoeutectic alloy. CN109777986A discloses a method for preparing and optimizing the structure of an in-situ generated Mg2Si reinforced aluminum-based composite material, by adding 0.05-0.5% Sr, 0.05-1% P and 0.05-0.5% Ti. The properties of the alloy are improved by the adsorption and poisoning effect of the primary Mg2Si phase and eutectic Si by Sr, the nucleation inhibition effect of AlP on Mg2Si and the grain refinement effect of Al3Ti.
[0005] In the above methods, rare earths such as Sc and Er in CN109112368A and CN111118355A can refine Mg2Si and matrix structure, but Sc and Er are expensive and the addition amount is high, which limits their application. CN111411246A and CN109777986A use Bi / ultrasound and Sr-P-Ti to refine primary Mg2Si and matrix structure respectively, but do not involve eutectic Mg2Si. Summary of the invention
[0006] In order to overcome the problems existing in the prior art, one of the objectives of the present invention is to provide a method for preparing a Mg2Si in-situ self-generated aluminum-based composite material.
[0007] A second object of the present invention is to provide a Mg2Si in-situ self-generated aluminum-based composite material.
[0008] The third object of the present invention is to provide a method for preparing the above-mentioned Mg2Si in-situ self-generated aluminum-based composite material and the application of the prepared composite material in the automotive, communication, electronic or aerospace fields.
[0009] In order to achieve the above object, the technical solution adopted by the present invention is:
[0010] The first aspect of the present invention provides a method for preparing a Mg2Si in-situ self-generated aluminum-based composite material, comprising the following steps:
[0011] S1: melting and refining raw materials including Al and Si to obtain a first melt;
[0012] S2: melting Al-Be, Mg, and optionally added RE with the first melt, and then refining to obtain a second melt;
[0013] S3: fusing the second melt with the Al-Sr-RE composite modifier, and then casting to obtain the Mg2Si in-situ self-generated aluminum-based composite material;
[0014] RE is selected from at least one of La and Ce.
[0015] The present invention adopts the cheapest La and Ce rare earth elements, which have large reserves and are easy to obtain, and can significantly reduce production costs. In addition, by adding them in the form of Al-Sr-RE alloy, the modification effect on eutectic Mg2Si can be significantly improved, the Mg2Si phase can be refined and distributed more evenly, thereby improving the reinforcement effect of Mg2Si on aluminum-based composite materials, and the aluminum-based composite materials have higher plasticity.
[0016] In the present invention, fusion refers to the melting and integration of two or more solid metals or alloys.
[0017] Preferably, taking the mass percentage of the Mg2Si in-situ self-generated aluminum-based composite material as 100%, when the mass percentage of Mg2Si is greater than 13.9%, the step S2 is: melting Al-Be, Mg, RE and the first melt, and then refining to obtain a second melt.
[0018] Preferably, taking the mass percentage of the Mg2Si in-situ self-generated aluminum-based composite material as 100%, when the mass percentage of Mg2Si is ≤13.9%, the step S2 is: melting Al-Be and Mg with the first melt, and then refining to obtain a second melt.
[0019] According to the binary phase diagram of Al-Mg2Si, the eutectic point of Al-Mg2Si is 13.9%. When the mass percentage of Mg2Si is higher than this value, it is called a hypereutectic alloy, and the structure contains primary phase and eutectic phase. Otherwise, it is a hypoeutectic or eutectic alloy, and Mg2Si only exists in eutectic phase. Different modification methods need to be selected according to the different types of Mg2Si in the aluminum alloy. When Al-Mg2Si is eutectic or hypoeutectic, it only needs to be modified by Al-Sr-RE composite modification, that is, by adding a trace amount of Al-Sr-RE composite modifier, which contains Al4 (SrRE) and Al doped with Sr and RE. 11 (SrRE)3, with its high formation temperature and high chemical activity, gathers at the solid-liquid interface of the Mg2Si eutectic phase, inhibits the lateral growth of the eutectic Mg2Si, promotes its twinning transformation, and finally obtains fine whisker-like and granular eutectic Mg2Si, which significantly improves the plasticity of the aluminum alloy. When Al-Mg2Si is a hypereutectic, both the primary Mg2Si and the eutectic Mg2Si need to be modified at the same time. Therefore, it is necessary to add RE rare earth modifier in step S2 to modify the primary Mg2Si. The principle is that RE rare earth elements such as Ce and La have a high solid solubility in Mg2Si, but the solid solution of RE atoms causes a certain lattice distortion of Mg2Si, that is, it changes the surface energy of the Mg2Si crystal and inhibits the anisotropic growth of the Mg2Si crystal, thereby obtaining fine and dense polygonal primary Mg2Si.
[0020] Preferably, the refining step in step S1 is: using an inert gas as a carrier gas and introducing a halide salt refining agent for refining.
[0021] Preferably, the halide salt refining agent contains NaCl, KCl, and Na3AlF6.
[0022] Preferably, the refining step in step S2 is: using an inert gas as a carrier gas and introducing a sodium-free halide salt refining agent for refining.
[0023] Preferably, the sodium-free halide salt refining agent contains MgCl2, KCl, K3AlF6. The use of the sodium-free halide salt refining agent eliminates its adverse effects on high-Mg melt.
[0024] Preferably, the inert gas is selected from at least one of nitrogen, argon and xenon.
[0025] Preferably, based on the mass percentage of the composite modifier being 100%, the total mass percentage of Sr and RE is 10-18%.
[0026] Preferably, in the composite modifier, the mass ratio of Sr to RE is (0.5-1):1.
[0027] Preferably, based on the total mass percentage of the second melt being 100%, the mass percentage of the composite modifier does not exceed 1%.
[0028] Preferably, the amount of Be added is 0.002% to 0.01% based on the mass percentage of the first melt being 100%. In the present invention, the Be element can reduce the burning loss of Mg, Sr, and RE during the smelting process by forming a dense Be-containing oxide film on the surface of the aluminum melt to reduce the oxidation of Mg, Sr, and RE.
[0029] Preferably, based on the mass percentage of the first melt being 100%, the added amount of the RE is 0.06% to 0.1%.
[0030] Preferably, the preparation method further comprises a step of supplementing raw materials until the alloy composition meets the requirements; the step is located at least one of before step S2, during step S2, and after step S2.
[0031] Preferably, the casting step specifically comprises: removing scum on the surface of the melt, introducing the melt into a flow channel, and casting the melt after rotary degassing and double-layer filtration.
[0032] The second aspect of the present invention provides a Mg2Si in-situ self-generated aluminum-based composite material, which is prepared by the preparation method described in the first aspect of the present invention, and the average equivalent circular diameter of primary Mg2Si in the Mg2Si in-situ self-generated aluminum-based composite material does not exceed 15μm.
[0033] Preferably, the average equivalent circular diameter of the eutectic Mg2Si in the Mg2Si in-situ self-generated aluminum-based composite material does not exceed 3 μm.
[0034] Preferably, the average equivalent circular diameter of the primary Mg2Si in the Mg2Si in-situ self-generated aluminum-based composite material does not exceed 15 μm, and the sphericity is not less than 0.9; further preferably, the average equivalent circular diameter of the primary Mg2Si in the Mg2Si in-situ self-generated aluminum-based composite material does not exceed 13 μm, and the sphericity is not less than 0.9.
[0035] The third aspect of the present invention provides the application of the preparation method described in the first aspect of the present invention and / or the Mg2Si in-situ self-generated aluminum-based composite material described in the second aspect of the present invention in the automotive, communication, electronic or aerospace fields.
[0036] The beneficial effect of the present invention is that the preparation method of the present invention adopts Al-Sr-RE composite modifier to carry out composite modification of eutectic Mg2Si, and can simultaneously cooperate with RE to modify primary Mg2Si, thereby efficiently refining primary and eutectic Mg2Si, and significantly improving the morphology and distribution of primary and eutectic Mg2Si.
[0037] The average equivalent circular diameter of the primary Mg2Si of the Mg2Si in-situ self-generated aluminum-based composite material prepared by the preparation method of the present invention does not exceed 15μm, the sphericity is not less than 0.9, and the average equivalent circular diameter of the whiskers and particles of the eutectic Mg2Si does not exceed 3μm, which has more uniformity and significantly improves the plasticity of the Al-Mg2Si in-situ self-generated aluminum-based composite material. BRIEF DESCRIPTION OF THE DRAWINGS
[0038] Figure 1 This is a scanning electron microscope image of the Mg2Si in-situ self-generated aluminum-based composite material in Example 1.
[0039] Figure 2 This is a scanning electron microscope image of the Mg2Si in-situ self-generated aluminum-based composite material in Comparative Example 1.
[0040] Figure 3 This is a scanning electron microscope image of the Mg2Si in-situ self-generated aluminum-based composite material in Comparative Example 2.
[0041] Figure 4 This is the XRD diagram of the Mg2Si in-situ self-generated aluminum-based composite material in Example 1. DETAILED DESCRIPTION
[0042] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. The reagents or instruments used that do not indicate the manufacturer are all conventional products that can be purchased commercially.
[0043] When preparing the Mg2Si in-situ self-generated aluminum-based composite material of the present invention, first, the existence form of Mg2Si in the composite material is determined. According to the binary phase diagram of Al-Mg2Si, the eutectic point of Al-Mg2Si is 13.9%. When the mass percentage of Al-Mg2Si is greater than 13.9%, it is called a hypereutectic alloy, and the structure contains a primary phase and a eutectic phase; on the contrary, when the mass percentage of Al-Mg2Si is less than or equal to 13.9%, it is a hypoeutectic or eutectic alloy, and only a eutectic phase exists. Secondly, different preparation methods are selected according to the type of composite material. When Al-Mg2Si is a hypereutectic (i.e., the mass percentage of Al-Mg2Si is greater than 13.9%), rare earth metals need to be added in step (5) for modification treatment to modify the primary Mg2Si. The principle is that rare earth elements such as Ce and La have a high solid solubility in Mg2Si. The solid solution of Ce and La causes a certain lattice distortion of Mg2Si, that is, the surface energy of the Mg2Si crystal is changed, and the anisotropic growth of the Mg2Si crystal is inhibited, thereby obtaining fine and dense polygonal primary Mg2Si. When Al-Mg2Si is a eutectic or hypoeutectic (i.e., the mass percentage of Al-Mg2Si is ≤13.9%), there is no need to add rare earth metals for modification treatment in step (5). It is only necessary to use Al-Sr-RE composite modifier treatment, that is, by adding a trace amount of Al-Sr-RE intermediate alloy, which contains Al4 (SrRE) and Al doped with Sr and RE. 11 (SrRE)3, by virtue of its higher formation temperature and high chemical activity, aggregates at the solid-liquid interface of the eutectic Mg2Si phase, inhibits the lateral growth of the eutectic Mg2Si, promotes its twinning transformation, and ultimately obtains fine whisker-like and granular eutectic Mg2Si, significantly improving the plasticity of the alloy.
[0044] The specific implementation of the present invention is further described in detail below in conjunction with specific embodiments:
[0045] Example 1
[0046] This example provides a method for preparing a Mg2Si in-situ self-generated aluminum-based composite material, the preparation method comprising the following steps:
[0047] (1) Component design and ingredients: The mass ratio of each element is calculated according to the composition of Al-15% Mg2Si alloy (i.e., the mass percentage of Mg2Si in-situ self-generated aluminum-based composite material is 100%, and the mass percentage of Mg2Si is 15%), and then the required weight of various raw materials is formulated.
[0048] (2) Melting: Si and 80% Al are added into a melting furnace and then heated to 800°C for melting.
[0049] (3) First refining: add 20% aluminum ingots, reduce the melt temperature to 750°C, use 99.99% pure nitrogen as a carrier, and introduce a halide refining agent mainly composed of NaCl, KCl, and Na3AlF6. The halide refining agent is a commercially available product. Any commercially available refining agent containing these three components can be used;
[0050] (4) Be addition: adding Al-Be alloy to a Be addition amount of 0.005% of the total mass of the melt, then removing the surface scum and taking samples to test the alloy composition;
[0051] (5) Adding Mg and adjusting the composition: According to the composition test results, the raw materials and Mg are supplemented; and a mixed rare earth of La and Ce accounting for 0.06% of the total mass of the melt is added, in which the mass ratio of La to Ce is 1:1; then the electromagnetic stirring system is turned on to promote the melting of the raw materials; the alloy composition is tested for the second time and the alloy composition is adjusted to meet the requirements.
[0052] (6) Second refining: using 99.99% pure argon as a carrier, a Na-free halide refining agent mainly composed of MgCl2, KCl, and K3AlF6 is introduced. The halide refining agent is a commercially available product. Any commercially available refining agent containing these three components can be used;
[0053] (7) Al-Sr-RE composite modifier: add 0.4% Al-6Sr-10Ce composite modifier (the mass percentage of Sr is 6% and the mass percentage of Ce is 10% based on the mass percentage of the composite modifier as 100%) to the total mass of the melt, and keep it at a temperature for 30 min;
[0054] (8) Casting: Remove the surface scum, introduce the melt into the flow channel, and after rotary degassing and double-layer filtration, introduce it into the insulation furnace to directly supply the casting equipment. After casting and cooling, the Mg2Si in-situ self-generated aluminum-based composite material in this example is obtained, which is recorded as Al-15%Mg2Si alloy.
[0055] Example 2
[0056] This example provides a method for preparing a Mg2Si in-situ self-generated aluminum-based composite material, the preparation method comprising the following steps:
[0057] (1) Component design and formulation: According to the composition of Al-13.9% Mg2Si alloy (the mass percentage of Mg2Si in-situ self-generated aluminum-based composite material is 100%, and the mass percentage of Mg2Si is 13.9%), the mass ratio of each element is calculated and the required weight of various raw materials is formulated.
[0058] (2) Melting: Si and 85% aluminum ingots are added into a melting furnace, and then heated to 780°C for melting.
[0059] (3) First refining: Add the remaining aluminum ingots, lower the melt temperature to 740°C, use 99.99% pure nitrogen as a carrier, and introduce a halide refining agent (commercially available product) mainly composed of NaCl, KCl, and Na3AlF6;
[0060] (4) Be addition: adding Al-Be alloy to a Be addition amount of 0.002% of the total mass of the melt, then removing the surface scum and taking samples to test the alloy composition;
[0061] (5) Adding Mg and adjusting the composition: According to the composition test results, the raw materials and Mg are added; then the electromagnetic stirring system is turned on to promote the melting of the raw materials; the alloy composition is tested for the second time and the alloy composition is adjusted to meet the requirements.
[0062] (6) Second refining: using 99.99% pure argon as a carrier, introducing a Na-free halide refining agent (commercially available product) mainly composed of MgCl2, KCl, and Na3AlF6;
[0063] (7) Al-Sr-RE composite modification: add 0.3% Al-8Sr-8RE composite modifier to the total mass of the melt (the mass percentage of the composite modifier is 100%, the mass percentage of Sr is 8%, the mass percentage of RE is 8%, and RE is a melt of La and Ce with a mass ratio of 1:3), and keep it at temperature for 20 min;
[0064] (8) Casting: Remove the surface scum, introduce the melt into the flow channel, and cast it into an ingot after rotary degassing and double-layer filtration to obtain the Mg2Si in-situ self-generated aluminum-based composite material in this example, which is recorded as Al-13.9% Mg2Si alloy.
[0065] Example 3
[0066] This example provides a method for preparing a Mg2Si in-situ self-generated aluminum-based composite material, the preparation method comprising the following steps:
[0067] (1) Component design and formulation: According to the composition of Al-20% Mg2Si alloy (the mass percentage of Mg2Si in-situ self-generated aluminum-based composite material is 100%, and the mass percentage of Mg2Si is 20%), the mass ratio of each element is calculated and the required weight of various raw materials is formulated.
[0068] (2) Melting: Si and 70% aluminum ingots are added into a melting furnace, and then the temperature is raised to 820°C for melting.
[0069] (3) First refining: Add the remaining aluminum ingots, lower the melt temperature to 760°C, use 99.99% pure nitrogen as a carrier, and introduce a halide refining agent (commercially available product) mainly composed of NaCl, KCl, and Na3AlF6;
[0070] (4) Be addition: Add Al-Be alloy to a Be addition amount of 0.01% of the total mass of the melt, then remove the surface scum and take samples to test the alloy composition;
[0071] (5) Adding Mg and adjusting the composition: According to the composition test results, the raw materials and Mg are supplemented; and 0.1% of Ce rare earth is added to the total mass of the melt; then the electromagnetic stirring system is turned on to promote the melting of the raw materials; the alloy composition is tested for the second time and the alloy composition is adjusted to meet the requirements.
[0072] (6) Second refining: using 99.99% pure argon as a carrier, introducing a Na-free halide refining agent (commercially available product) mainly composed of MgCl2, KCl, and Na3AlF6;
[0073] (7) Al-Sr-RE composite modification: add 0.5% of Al-5Sr-7RE composite modifier to the total mass of the melt (the mass percentage of the composite modifier is 100%, the mass percentage of Sr is 5%, the mass percentage of RE is 7%, and RE is Ce), and keep it at temperature for 45 min;
[0074] (8) Casting: Remove the surface scum, introduce the melt into the flow channel, and cast it into a rod after rotary degassing and double-layer filtration to obtain the Mg2Si in-situ self-generated aluminum-based composite material in this example, which is recorded as Al-20% Mg2Si alloy.
[0075] Example 4
[0076] This example provides a method for preparing a Mg2Si in-situ self-generated aluminum-based composite material, the preparation method comprising the following steps:
[0077] (1) Component design and formulation: According to the composition of Al-10% Mg2Si alloy (the mass percentage of Mg2Si in-situ self-generated aluminum-based composite material is 100%, and the mass percentage of Mg2Si is 10%), the mass ratio of each element is calculated and the required weight of various raw materials is formulated.
[0078] (2) Melting: Si and 95% Al are added into a melting furnace and then heated to 760°C for melting.
[0079] (3) First refining: Add the remaining aluminum ingots, lower the melt temperature to 750°C, use 99.99% pure nitrogen as a carrier, and introduce a halide refining agent (commercially available product) mainly composed of NaCl, KCl, and Na3AlF6;
[0080] (4) Be addition: adding Al-Be alloy to a Be addition amount of 0.003% of the total mass of the melt, then removing the surface scum and taking samples to test the alloy composition;
[0081] (5) Adding Mg and adjusting the composition: According to the composition test results, the raw materials and Mg are added; then the electromagnetic stirring system is turned on to promote the melting of the raw materials; the alloy composition is tested for the second time and the alloy composition is adjusted to meet the requirements.
[0082] (6) Second refining: using 99.99% pure argon as a carrier, introducing a Na-free halide refining agent (commercially available product) mainly composed of MgCl2, KCl, and Na3AlF6;
[0083] (7) Al-Sr-RE composite modification: add 0.4% Al-5Sr-5La composite modifier to the total mass of the melt (the mass percentage of Sr is 5% and the mass percentage of La is 5%, based on the mass percentage of the composite modifier as 100%), and keep it at a temperature for 60 min;
[0084] (8) Casting: Remove the surface scum, introduce the melt into the flow channel, and after rotary degassing and double-layer filtration, introduce it into the insulation furnace to directly supply the casting equipment. After casting and cooling, the Mg2Si in-situ self-generated aluminum-based composite material in this example is obtained, which is recorded as Al-10% Mg2Si alloy.
[0085] Comparative Example 1
[0086] The preparation method of the Mg2Si in-situ self-generated aluminum-based composite material in this example is different from that in Example 1 only in that: in this example, the mixed rare earth of La and Ce is not added in step (5), and the Al-6Sr-10RE composite modifier is not used in step (7).
[0087] Comparative Example 2
[0088] The only difference between the preparation method of the Mg2Si in-situ self-generated aluminum-based composite material in this example and that in Example 1 is that the Al-6Sr-10RE composite modifier is not used in step (7) of this example.
[0089] Comparative Example 3
[0090] The preparation method of the Mg2Si in-situ self-generated aluminum-based composite material in this example is different from that in Example 1 only in that an equal amount of Al-Sr is used in step (7) of this example to replace the Al-6Sr-10Ce composite modifier in Example 1.
[0091] Performance Test:
[0092] The surface morphologies of the Mg2Si in-situ self-generated aluminum-based composite materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 were tested by scanning electron microscopy. The specific test images are shown in FIG. Figure 1 , Figure 2 and Figure 3 As shown. Figures 1 to 3It can be seen that compared with comparative examples 1 to 2, Example 1 can significantly improve the morphology and distribution of primary Mg2Si and eutectic Mg2Si by introducing mixed rare earths of La and Ce and Al-Sr-RE composite modifiers into the composite material, refine the size of primary Mg2Si and eutectic Mg2Si, and make the distribution of primary Mg2Si and eutectic Mg2Si more uniform.
[0093] The XRD data of the Mg2Si in-situ self-generated aluminum-based composite material in Example 1 were tested by X-ray diffractometer. The specific test results are as follows: Figure 4 As shown by Figure 4 It can be seen that in the Mg2Si in-situ self-generated aluminum-based composite material in Example 1, Mg and Si react in-situ to generate Mg2Si.
[0094] The mechanical properties of the Mg2Si in-situ self-generated aluminum-based composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were tested respectively, and the tensile strength, yield strength and elongation were tested according to the methods listed in the national standard GB / T 228.1-2021 "Tensile test of metal materials Part 1: Room temperature test method"; the mechanical properties data measured according to the above test method are recorded in Table 1 below.
[0095] Table 1 Mechanical properties of Mg2Si in-situ aluminum matrix composites
[0096]
[0097] As shown in Table 1, with the increase of Mg2Si content in the Mg2Si in-situ self-generated aluminum-based composite material, the tensile strength and yield strength are improved to a certain extent, while the elongation is significantly reduced. By comparing Example 1 with Comparative Examples 1 to 3, it can be seen that the introduction of mixed rare earths of La and Ce, Al-6Sr-10RE, into the aluminum-based composite material can improve the tensile strength and yield strength of the composite material to a certain extent, and the elongation is greatly improved. Among them, compared with Comparative Example 1, the elongation of Example 1 is increased by 1.6 times, compared with Comparative Example 2, the elongation of Example 1 is increased by about 60%, and compared with Comparative Example 3, the elongation of Example 1 is increased by about 30%.
[0098] The average equivalent circle diameters of the primary Mg2Si and the eutectic Mg2Si in the preparation methods of Examples 1 to 4 and Comparative Examples 1 to 3 were tested respectively. The specific testing method was: image processing software was used to test and analyze Mg2Si in 5 to 30 50 to 500 times magnification metallographic photographs. The statistically measured average equivalent circle diameter data were shown in Table 2 below.
[0099] Table 2 Average equivalent circle diameter of primary Mg2Si and eutectic Mg2Si
[0100]
[0101] It can be seen from Table 2 that compared with comparative examples 1 to 3, the sizes of the primary Mg2Si and eutectic Mg2Si in Example 1 are significantly refined, with a reduction of about 50%. Compared with comparative example 2, the size of the eutectic Mg2Si in Example 1 is reduced by about 50%, and compared with comparative example 3, the size of the eutectic Mg2Si in Example 1 is reduced by 33.7%.
[0102] In summary, the preparation method of the present invention improves the morphology of primary and eutectic Mg2Si by introducing mixed rare earth of La and Ce and Al-Sr-RE composite modifier into the composite material, thereby improving the comprehensive mechanical properties of the composite material, especially improving the elongation. Specifically, in the Mg2Si in-situ self-generated aluminum-based composite material of the present invention, the average equivalent circular diameter of primary Mg2Si does not exceed 15μm, and the sphericity is not less than 0.9. The average equivalent circular diameter of eutectic Mg2Si does not exceed 3μm, and the plasticity of the alloy is more than 2 times higher than that of the unmodified one.
[0103] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.
Claims
1. A method for preparing a Mg2Si in-situ self-generated aluminum-based composite material, characterized in that: The following steps are involved: S1: melting and refining raw materials including Al and Si to obtain a first melt; S2: melting Al-Be, Mg, and optionally added RE with the first melt, and then refining to obtain a second melt; S3: fusing the second melt with the Al-Sr-RE composite modifier, and then casting to obtain the Mg2Si in-situ self-generated aluminum-based composite material; RE is selected from at least one of La and Ce.
2. The method for preparing the Mg2Si in-situ self-generated aluminum-based composite material according to claim 1, characterized in that: Taking the mass percentage of the Mg2Si in-situ self-generated aluminum-based composite material as 100%, when the mass percentage of Mg2Si is greater than 13.9%, the step S2 is: melting Al-Be, Mg, RE and the first melt, and then refining to obtain a second melt.
3. The method for preparing the Mg2Si in-situ self-generated aluminum-based composite material according to claim 1, characterized in that: Taking the mass percentage of the Mg2Si in-situ self-generated aluminum-based composite material as 100%, when the mass percentage of Mg2Si is ≤13.9%, the step S2 is: melting Al-Be and Mg with the first melt, and then refining to obtain a second melt.
4. The method for preparing the Mg2Si in-situ self-generated aluminum-based composite material according to claim 1, characterized in that: The refining step in step S1 is: using an inert gas as a carrier gas and introducing a halide salt refining agent for refining; and / or, The refining step in step S2 is: using an inert gas as a carrier gas and introducing a sodium-free halide salt refining agent for refining.
5. The method for preparing the Mg2Si in-situ self-generated aluminum-based composite material according to claim 1, characterized in that: Taking the mass percentage of the composite modifier as 100%, the total mass percentage of Sr and RE is 10-18%.
6. The method for preparing the Mg2Si in-situ self-generated aluminum-based composite material according to claim 5, characterized in that: In the composite modifier, the mass ratio of Sr to RE is (0.5-1):
1.
7. The method for preparing the Mg2Si in-situ self-generated aluminum-based composite material according to claim 1, characterized in that: Taking the total mass percentage of the second melt as 100%, the mass percentage of the composite modifier does not exceed 1%.
8. The method for preparing the Mg2Si in-situ self-generated aluminum-based composite material according to claim 1, characterized in that: Taking the mass percentage of the first melt as 100%, the amount of Be added is 0.002% to 0.01%; And / or, based on the mass percentage of the first melt being 100%, the added amount of the RE is 0.06% to 0.1%.
9. A Mg2Si in-situ self-generated aluminum-based composite material, characterized in that: The Mg2Si in-situ self-generated aluminum-based composite material is prepared by the preparation method described in any one of claims 1 to 8, and the average equivalent circle diameter of the primary Mg2Si does not exceed 15 μm.
10. Application of the preparation method according to any one of claims 1 to 8 and / or the Mg2Si in-situ self-generated aluminum-based composite material according to claim 9 in the fields of automobiles, communications, electronics or aerospace.