Method for preparing high-toughness mixed-crystal isomeric magnesium-based composite material through cooperation of silicon carbide particles and large plastic deformation
By adding micron silicon carbide particles to the magnesium alloy and using a multi-step process, a high-strength mixed crystal isomer magnesium-based composite material was successfully prepared, which solved the problem of low elongation of breaking at room temperature, and improved its strength, wear resistance and plasticity.
Patent Information
- Application Number
- CN202510088574.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-21
- Publication Date
- 2025-05-13
AI Technical Summary
Magnesium-based composites have low elongation of fracture at room temperature, making it difficult to prepare high-strength magnesium-based composites, and their plasticity and wear resistance are insufficient, which limits their application range.
High-strength mixed crystal isomer magnesium composite materials are prepared by adding micron silicon carbide particles to the magnesium alloy and using semi-solid casting, solid solution heat treatment, etc., angle extrusion and single-pass rolling processes.
This method not only improves the strength and wear resistance of magnesium-based composite materials, but also effectively adjusts the degree of dynamic recrystallization during large plastic deformation, obtains a large proportion of fine crystal mixed crystal structure, and improves the comprehensive mechanical properties of the material.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of magnesium-based composite material processing, and in particular to a method for preparing a high-strength and tough mixed-crystal heterogeneous magnesium-based composite material by using silicon carbide particles in coordination with large plastic deformation. Background Art
[0002] With the rapid development of science and technology and the increasing scale of industrialization, resource, energy and environmental issues are becoming increasingly prominent. As the basic industrial carrier, the consumption of metal materials has increased sharply, while the resources of the earth's crust are becoming increasingly impoverished. According to statistics, metal copper, lead and zinc can only last for a few decades, and aluminum and iron can only be used for one hundred to three hundred years. Magnesium is one of the most abundant light metal elements on the earth, accounting for 2.3% of the metal ore content in the surface layer of the earth's crust. Its content in salt lakes and oceans is also very large, which can be said to be inexhaustible. Magnesium alloys have many excellent properties, such as high specific strength and specific stiffness, good damping performance and cutting performance, excellent electromagnetic shielding performance, good biocompatibility, etc., and have broad application prospects in aerospace, national defense, automobiles, electronic mobile devices and biomedicine. Today, when traditional metal resources are becoming increasingly exhausted, vigorously developing magnesium metal materials is an important measure to cope with the current energy crisis, environmental pollution, global warming and future metal crisis, and it has important strategic significance for the sustainable development of society.
[0003] As the lightest metal structural material, magnesium alloy has been developed rapidly, but its low high temperature and room temperature strength, low elastic modulus, low wear resistance and high temperature resistance restrict its application. Adding an appropriate amount of reinforcing phase to magnesium alloy to prepare magnesium-based composite materials can not only maintain the advantages of magnesium alloy light weight, but also enable the material to obtain new performance (such as wear resistance, high temperature resistance, etc.), which has greater application potential than traditional metal and aluminum-based composite materials. However, the inherent close-packed hexagonal crystal structure of magnesium determines the poor plasticity of magnesium-based composite materials, and the interface and other problems in the composite material cause its plastic toughness to further decrease. The elongation at break of magnesium-based composite materials at room temperature is generally less than 5%. Therefore, it is an urgent problem to be solved in the current field of magnesium metal materials to prepare high-strength and toughness magnesium-based composite materials, study their strengthening and toughening mechanism and preparation method, promote low-cost, large-scale commercial production of magnesium metal materials, and expand the application range of magnesium metal materials.
[0004] In order to improve plasticity while maintaining high strength of fine-grained materials, some novel microstructures can be constructed in metal materials, such as gradient structures, lamellar structures and multi-level twin structures, so that the internal spatial structure, composition, strength, etc. of the material show non-uniform distribution characteristics, and a "heterogeneous metal material" composed of "soft zone" and "hard zone" structural units is designed. When heterogeneous materials are stretched by external forces, the hard and soft parts deform unevenly. Due to the continuity of the material, a strain gradient will be generated near the soft and hard interface. In order to adapt to the strain gradient, geometrically required dislocations are generated, back stress pointing to the dislocation source is generated in the soft zone, and forward stress is generated in the hard zone. The back stress can prevent the plastic deformation of the soft zone and strengthen the soft zone. Heterogeneous metal materials can accumulate more geometrically required dislocations than homogeneous structures, induce more significant back stress strengthening, and enable heterogeneous metal materials to obtain excellent strength and toughness matching.
[0005] Currently, no effective solution has been proposed for the problems in the related technologies. Summary of the invention
[0006] In view of the problems in the related art, the present invention proposes a method for preparing high-strength and tough mixed-crystal heterogeneous magnesium-based composite materials by using silicon carbide particles in coordination with large plastic deformation, so as to overcome the above-mentioned technical problems existing in the existing related technology.
[0007] To this end, the specific technical solution adopted by the present invention is as follows:
[0008] A method for preparing a high-strength and tough mixed-crystal heterogeneous magnesium-based composite material by using silicon carbide particles in coordination with large plastic deformation, the method comprising the following steps:
[0009] S1. Putting a magnesium alloy into a resistance furnace, introducing a mixed gas consisting of sulfur hexafluoride and carbon dioxide into the resistance furnace, and heating the furnace to melt the magnesium alloy;
[0010] S2, after cooling the molten magnesium alloy to a semi-solid state, adding preheated silicon carbide particles and stirring, pouring the stirred melt into a steel mold and cooling it to obtain a cast magnesium-based composite material;
[0011] S3, performing a solid solution treatment on the as-cast magnesium-based composite material, and placing the as-cast magnesium-based composite material after the solid solution treatment into an equal channel angular extrusion die for extrusion;
[0012] S4. After the cast magnesium-based composite material after extrusion is cooled, the cast magnesium-based composite material is cut into thick plates and preheated, and then put into a rolling mill for single-pass rolling processing to obtain a silicon carbide particle-reinforced magnesium-based composite material with heterogeneous structure.
[0013] Furthermore, the volume ratio of sulfur hexafluoride to carbon dioxide in the mixed gas is 1:100.
[0014] Furthermore, the magnesium alloy is a cuboid of 40 mm×40 mm×80 mm.
[0015] Furthermore, the silicon carbide particles are irregular in shape, have a purity of 98.8%, and have an average particle size of 10 μm.
[0016] Furthermore, the silicon carbide particles are added in an amount of 5 vol.%, and the rest is magnesium alloy.
[0017] Furthermore, the temperature of heating the molten magnesium alloy is 720°C, and the temperature of cooling it to a semi-solid state is 600°C.
[0018] Furthermore, the preheating temperature of the silicon carbide particles is 600° C., the stirring speed is 1000 r / min, and the stirring time is 2 hours.
[0019] Furthermore, before the solution treatment, the cast magnesium-based composite material is wrapped with tin foil and buried in graphite powder to isolate the air. The temperature of the solution treatment is 420° C. and the duration is 20 hours.
[0020] Furthermore, before extrusion, the cast magnesium-based composite material is preheated to 300° C. and kept warm for 30 minutes;
[0021] The processing size of the equal channel angular extrusion die is 20 mm×20 mm×45 mm, and the cast magnesium-based composite material is subjected to 16 extrusion processes.
[0022] Furthermore, the preheating temperature of the thick plate is 400° C., the holding time is 5 minutes, and the thickness of the rolling process is 6.7 mm to 7 mm.
[0023] The beneficial effects of the present invention are:
[0024] 1. The method of the present invention for obtaining a mixed-crystal heterogeneous high-strength and tough magnesium-based composite material by using silicon carbide particles in coordination with large plastic deformation is composed of semi-solid casting, solution heat treatment, equal channel angular extrusion and single-pass rolling processes. The addition of micron silicon carbide particles can not only obtain better strength and wear resistance, but also effectively adjust the degree of dynamic recrystallization during large plastic deformation to obtain a large proportion of fine-grained mixed crystal structure; the equal channel angular extrusion process can obtain a uniform structure and a weakened non-basal surface texture, which is convenient for subsequent rolling deformation, increases the downward pressure of a single-pass rolling, and reduces rolling cracking, thereby improving production efficiency, reducing energy consumption and saving costs.
[0025] 2. The innovation of the present invention lies in the synergistic effect of material composition and preparation method. It adds micron SiC particles to coordinate plastic deformation, utilizes the uncoordinated deformation of micron particles and matrix alloy, produces uneven dynamic recrystallization in the matrix alloy, adjusts the matrix grain size, and obtains coarse and fine mixed crystal heterogeneous structure; in the preparation method, large plastic deformation adopts equal channel angular extrusion to obtain better plastic deformation, and subsequent rolling processing can implement single-pass large reduction, thereby improving processing efficiency; through the coordinated large plastic deformation of silicon carbide particles, the strength of magnesium-based composite materials is further improved while ensuring its plasticity. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0027] Figure 1 This is a flow chart of a method for preparing a high-strength and tough mixed-crystal heterogeneous magnesium-based composite material by using silicon carbide particles in coordination with large plastic deformation according to an embodiment of the present invention;
[0028] Figure 2 This is a metallographic structure diagram of a cast magnesium-based composite material in a method for preparing a high-strength and tough mixed-crystal heterogeneous magnesium-based composite material by using silicon carbide particles in coordination with large plastic deformation according to an embodiment of the present invention;
[0029] Figure 3 It is a metallographic structure diagram of a medium channel angular extrusion ultrafine grain magnesium-based composite material according to a method for preparing a high-strength and tough mixed-crystal heterogeneous magnesium-based composite material by using silicon carbide particles in coordination with large plastic deformation according to an embodiment of the present invention;
[0030] Figure 4 It is a metallographic structure diagram of a mixed crystal heterogeneous magnesium-based composite material with silicon carbide particles in cooperation with large plastic deformation in a method for preparing a high-strength and tough mixed crystal heterogeneous magnesium-based composite material with silicon carbide particles in cooperation with large plastic deformation according to an embodiment of the present invention;
[0031] Figure 5 This is a SEM organizational structure diagram of the fine grain area of a mixed crystal heterogeneous magnesium-based composite material in a method for preparing a high-strength and tough mixed crystal heterogeneous magnesium-based composite material by coordinated large plastic deformation of silicon carbide particles according to an embodiment of the present invention. DETAILED DESCRIPTION
[0032] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention and are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in the field should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.
[0033] According to an embodiment of the present invention, a method for preparing a high-strength and tough mixed-crystal heterogeneous magnesium-based composite material by using silicon carbide particles in coordination with large plastic deformation is provided.
[0034] The present invention is further described with reference to the accompanying drawings and specific embodiments. Figure 1-Figure 5 As shown, according to one embodiment of the present invention, a method for preparing a high-strength and tough mixed-crystal heterogeneous magnesium-based composite material by using silicon carbide particles in coordination with large plastic deformation is provided. The method for preparing the high-strength and tough mixed-crystal heterogeneous magnesium-based composite material comprises the following steps:
[0035] S1. Put a magnesium alloy into a resistance furnace, introduce a mixed gas consisting of sulfur hexafluoride and carbon dioxide into the resistance furnace, and heat the furnace to melt the magnesium alloy.
[0036] In one embodiment, the volume ratio of sulfur hexafluoride to carbon dioxide in the mixed gas is 1:100.
[0037] In one embodiment, the magnesium alloy is a cuboid of 40 mm×40 mm×80 mm.
[0038] In one embodiment, the temperature of heating the molten magnesium alloy is 720°C, and the temperature of cooling to a semi-solid state is 600°C.
[0039] It should be explained that the magnesium alloy is AZ91 alloy (bulk casting magnesium alloy), and the metallographic structure of the untreated cast SiCp (silicon carbide particles) / AZ91 magnesium-based composite material has a coarse dendrite second phase and agglomerated silicon carbide particles. Figure 2 shown.
[0040] S2. After the molten magnesium alloy is cooled to a semi-solid state, preheated silicon carbide particles are added and stirred, and the stirred melt is poured into a steel mold and cooled to obtain a cast magnesium-based composite material.
[0041] In one embodiment, the silicon carbide particles are irregular in shape, have a purity of 98.8%, and have an average particle size of 10 μm.
[0042] In one embodiment, the silicon carbide particles are added in an amount of 5 vol.%, and the rest is magnesium alloy.
[0043] In one embodiment, the preheating temperature of the silicon carbide particles is 600° C., the stirring speed is 1000 r / min, and the stirring time is 2 hours.
[0044] S3, performing a solid solution treatment on the cast magnesium-based composite material, and placing the cast magnesium-based composite material after the solid solution treatment into an equal channel angular extrusion die for extrusion.
[0045] In one embodiment, before the solution treatment, the cast magnesium-based composite material is wrapped with tin foil and buried in graphite powder to isolate it from air. The temperature of the solution treatment is 420° C. and the duration is 20 hours.
[0046] In one embodiment, before extrusion, the cast magnesium-based composite material is preheated to 300° C. and kept warm for 30 minutes; the processing size of the equal channel angular extrusion die is 20 mm×20 mm×45 mm, and the cast magnesium-based composite material is extruded 16 times.
[0047] It should be explained that the cast SiCp / AZ91 magnesium-based composite material was solution treated, and then placed in an ECAP (equal channel angular extrusion) die and heated to 300°C for 30 minutes, and subjected to 16 passes of ECAP processing. After ECAP processing, the average grain size was about 1 micron, such as Figure 3 shown.
[0048] S4. After the cast magnesium-based composite material after extrusion is cooled, the cast magnesium-based composite material is cut into thick plates and preheated, and then put into a rolling mill for single-pass rolling processing to obtain a silicon carbide particle-reinforced magnesium-based composite material with heterogeneous structure.
[0049] In one embodiment, the preheating temperature of the thick plate is 400° C., the holding time is 5 minutes, and the thickness of the rolling process is 6.7 mm to 7 mm.
[0050] It should be explained that the magnesium-based composite material processed by ECAP was subjected to multi-pass rolling processing at a temperature of 400° C., a warm time of 5 min, a single-pass reduction of 70%, and rolled into a plate with a thickness of 2 mm. Figure 4 The metallographic structure of SiC synergistic large plastic deformation mixed crystal heterogeneous magnesium-based composite material can be seen. It can be seen that the structure is a mixture of coarse crystals and fine crystals. The coarse crystal grains are deformed to different degrees, and the coarse and fine crystals are mixed to form a mixed crystal heterogeneous structure, thereby improving the mechanical properties of the composite material.
[0051] also, Figure 5It is the SEM structure of the fine-grained area of the mixed-crystal heterogeneous magnesium-based composite material. The fine grains are uniform and small, and a large amount of second phase is precipitated and dispersed, which effectively pins the grain boundaries during the deformation process and plays a role in grain refinement. The large proportion of fine-grained areas plays a good strengthening and toughening effect in the later tensile properties.
[0052] Table 1 Comparison of mechanical properties of as-cast, ultrafine-grained and mixed-grained heterogeneous magnesium-based composites
[0053]
[0054] The prepared mixed crystal heterogeneous magnesium-based composite material and the equal-channel angular extrusion ultrafine-grained magnesium-based composite material were subjected to mechanical property tests. The results are shown in Table 1. The tensile strength of the SiCp synergistic large plastic deformation mixed crystal heterogeneous magnesium-based composite material is 426 MPa, the yield strength is 372 MPa, and the elongation is 6.8%, which has good comprehensive mechanical properties.
[0055] In summary, with the aid of the above technical scheme of the present invention, the method of the present invention for obtaining a mixed-crystal heterogeneous high-strength and tough magnesium-based composite material by coordinating large plastic deformation with silicon carbide particles is composed of semi-solid casting, solution heat treatment, equal channel angular extrusion and single-pass rolling process. The addition of micron silicon carbide particles can not only obtain better strength and wear resistance, but also effectively adjust the degree of dynamic recrystallization during large plastic deformation to obtain a large proportion of fine-grained mixed crystal structure; the equal channel angular extrusion process can obtain a uniform structure and a weakened non-basal texture, which is convenient for subsequent rolling deformation, increases the pressure of a single-pass rolling, and reduces rolling cracking, thereby improving production efficiency. The invention improves production efficiency, reduces energy consumption and saves costs; the innovation of the invention lies in the synergistic effect of material composition and preparation method, which produces uneven dynamic recrystallization in the matrix alloy by adding micron SiC particles to coordinate plastic deformation, utilizes the uncoordinated deformation of micron particles and matrix alloy, adjusts the matrix grain size, and obtains coarse-fine mixed crystal heterogeneous structure; in the preparation method, large plastic deformation adopts equal channel angular extrusion, which can obtain better plastic deformation, and subsequent rolling processing can implement single-pass large reduction, thereby improving processing efficiency; through the coordinated large plastic deformation of silicon carbide particles, the strength of magnesium-based composite materials is further improved, while its plasticity is guaranteed.
[0056] 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 method for preparing high-strength and tough mixed-crystal heterogeneous magnesium-based composite materials by using silicon carbide particles in coordination with large plastic deformation, characterized in that: The preparation method of the high-strength and toughness mixed-crystal heterogeneous magnesium-based composite material comprises the following steps: S1. Putting a magnesium alloy into a resistance furnace, introducing a mixed gas consisting of sulfur hexafluoride and carbon dioxide into the resistance furnace, and heating the furnace to melt the magnesium alloy; S2, after cooling the molten magnesium alloy to a semi-solid state, adding preheated silicon carbide particles and stirring, pouring the stirred melt into a steel mold and cooling it to obtain a cast magnesium-based composite material; S3, performing a solid solution treatment on the as-cast magnesium-based composite material, and placing the as-cast magnesium-based composite material after the solid solution treatment into an equal channel angular extrusion die for extrusion; S4. After the cast magnesium-based composite material after extrusion is cooled, the cast magnesium-based composite material is cut into thick plates and preheated, and then put into a rolling mill for single-pass rolling processing to obtain a silicon carbide particle-reinforced magnesium-based composite material with heterogeneous structure.
2. The method for preparing high-strength and tough mixed-crystal heterogeneous magnesium-based composite materials by using silicon carbide particles in coordination with large plastic deformation according to claim 1, characterized in that: The volume ratio of sulfur hexafluoride to carbon dioxide in the mixed gas is 1:
100.
3. The method for preparing high-strength and tough mixed-crystal heterogeneous magnesium-based composite materials by using silicon carbide particles in coordination with large plastic deformation according to claim 1, characterized in that: The magnesium alloy is a rectangular parallelepiped with a size of 40 mm×40 mm×80 mm.
4. The method for preparing high-strength and tough mixed-crystal heterogeneous magnesium-based composite materials by using silicon carbide particles in coordination with large plastic deformation according to claim 1, characterized in that: The silicon carbide particles are irregular in shape, have a purity of 98.8%, and have an average particle size of 10 μm.
5. The method for preparing high-strength and tough mixed-crystal heterogeneous magnesium-based composite materials by using silicon carbide particles in coordination with large plastic deformation according to claim 1, characterized in that: The silicon carbide particles are added in an amount of 5 vol.%, and the rest is magnesium alloy.
6. The method for preparing high-strength and tough mixed-crystal heterogeneous magnesium-based composite materials by using silicon carbide particles in coordination with large plastic deformation according to claim 1, characterized in that: The temperature of heating the molten magnesium alloy is 720° C., and the temperature of cooling it to a semi-solid state is 600° C.
7. The method for preparing high-strength and tough mixed-crystal heterogeneous magnesium-based composite materials by using silicon carbide particles in coordination with large plastic deformation according to claim 1, characterized in that: The preheating temperature of the silicon carbide particles is 600° C., the stirring speed is 1000 r / min, and the stirring time is 2 hours.
8. The method for preparing high-strength and tough mixed-crystal heterogeneous magnesium-based composite materials by using silicon carbide particles in coordination with large plastic deformation according to claim 1, characterized in that: Before the solution treatment, the cast magnesium-based composite material is wrapped with tin foil and buried in graphite powder to isolate the air. The temperature of the solution treatment is 420° C. and the duration is 20 hours.
9. The method for preparing high-strength and tough mixed-crystal heterogeneous magnesium-based composite materials by using silicon carbide particles in coordination with large plastic deformation according to claim 1, characterized in that: Before extrusion, the cast magnesium-based composite material is preheated to 300° C. and kept warm for 30 minutes; The processing size of the equal channel angular extrusion die is 20 mm×20 mm×45 mm, and the cast magnesium-based composite material is subjected to 16 extrusion processes.
10. The method for preparing high-strength and tough mixed-crystal heterogeneous magnesium-based composite materials by using silicon carbide particles in coordination with large plastic deformation according to claim 1, characterized in that: The preheating temperature of the thick plate is 400° C., the holding time is 5 minutes, and the thickness of the rolling process is 6.7 mm to 7 mm.