Short-process casting device

Abstract

The utility model belongs to the field of structure and function integrated magnesium-based materials, and particularly relates to a short-process casting device, an aluminum-containing magnesium-based material and a casting method and application of the aluminum-containing magnesium-based material. According to the device, firstly, a SiC / Al pre-dispersion bar is prepared, then magnesium liquid pouring, pre-dispersion extrusion material melting and external field auxiliary layer-by-layer rapid solidification integrated treatment is carried out, under the ultrasonic cavitation effect, the electromagnetic stirring effect and the effect of a water cooling mold, Al and SiC are rapidly and evenly distributed, meanwhile, dispersed SiC particles rapidly enter a pasty area, and finally, the Al and the SiC particles are evenly dispersed. The method realizes layer-by-layer rapid solidification, effectively solves the problems of agglomeration caused by lack of external field assistance in the solidification process in the prior art and agglomeration of particles pushed to the grain boundary by matrix grains due to slow solidification speed, and in order to prevent melt oxidation, protective gas is distributed in the water cooling mold, and gas protection is performed on the surface of the melt in the whole process.

Description

Technical Field

[0001] The utility model belongs to the field of structure-function integrated magnesium-based materials, and particularly relates to a short-process melting and casting device. Background Technique

[0002] Magnesium-aluminum series magnesium alloys are the magnesium alloy systems with the longest development history, the most mature current applications and the largest consumption. Many mature alloy grades have been formed, such as AZ31, AZ40, AM50, AZ80, AZ91, etc., which can be widely used in cast magnesium alloys, die-cast magnesium alloys and wrought magnesium alloys, and have mature applications in the fields of automobiles, electronics, rail transit, electronics, weapons and equipment, etc. However, the elastic modulus of magnesium alloys is only 45 GPa, far lower than 70 GPa of aluminum alloys. The low elastic modulus has become one of the bottleneck problems restricting the high-end applications of magnesium alloys. The low elastic modulus will cause significant elastic deformation of magnesium alloy products under large loads or excessive amplitudes under vibration conditions, thus affecting the service effect. At present, the method to make up for the low elastic modulus of magnesium alloys is to increase the cross-sectional area, but this will weaken the weight reduction characteristics of magnesium alloys. Therefore, improving the elastic modulus is one of the important ways to expand the application range of magnesium alloys.

[0003] Heat treatment, plastic deformation and conventional alloying have limited effects on improving the elastic modulus of magnesium alloys. Introducing high-modulus reinforcement phases is the most effective method to improve the elastic modulus. Since the Japanese Toyota Company first used alumina short fiber-reinforced aluminum-based materials to manufacture diesel engine pistons in 1983, after more than 40 years of development, the production and application of particle-reinforced aluminum-based composites are quite mature at present, and particle-reinforced magnesium-based materials with more advantages in weight reduction have become a research hotspot.

[0004] Table 1 summarizes the physical and chemical properties of common reinforcement phases in magnesium alloys. The larger the elastic modulus of the reinforcement phase, the smaller the addition amount can be reduced, and the smaller the density of the reinforcement phase, the smaller the specific gravity sedimentation, thus greatly reducing the preparation difficulty. Therefore, SiC and nano-carbon materials have become the focus of attention, and SiC is superior to nano-carbon materials in terms of chemical stability and wettability to magnesium. Harbin Institute of Technology has been engaged in the research of magnesium matrix composites since the early 1990s. In 2018, the monograph "Particle Reinforced Magnesium Matrix Composites" written by Wang Xiaojun and Wu Kun was published, systematically summarizing the relationship between the preparation methods, microstructural characteristics and mechanical properties of SiC particle reinforced magnesium matrix composites. The reinforcing particles can be divided into three grades according to their average size, namely micron grade (1μm - 100μm), sub-micron grade (0.1μm - 1μm) and nano grade (1nm - 100nm). Initially, the research focus of magnesium matrix composites was on micron-sized reinforcing particles. However, while micron-sized reinforcing phase particles improve strength and modulus, they seriously deteriorate the plasticity of the material, resulting in a serious "stiffness-plasticity" mismatch problem, which has become the biggest obstacle restricting the practical application of particle reinforced magnesium matrix composites. Therefore, in the past decade, in the face of the difficult problem of the engineering application of particle reinforced magnesium matrix composites, researchers have turned their attention to nano-sized reinforcing particles and carried out a large number of research works. The preliminary conclusion is that nano-sized reinforcing phases can maximize the plasticity of the matrix while improving strength and stiffness, which has become the driving force for the continuous development of related research. Currently, the high point that countries in this field are competing for lies in how to achieve uniform dispersion of nano-reinforcing phase particles in the magnesium alloy matrix.

[0005] Table 1. Performance Indexes of Commonly Used Reinforcements in Magnesium Matrix Composites

[0006]

[0007] Considering comprehensively from the aspects of chemical stability, elastic modulus and wettability with the magnesium matrix, SiC particles have great advantages. Therefore, SiC nano-reinforced phase is preferably selected for nano-particle reinforced magnesium matrix composites. Existing technical literature shows that adding nano-SiC particles to magnesium alloys can improve mechanical properties, especially maintaining plasticity. The doctoral thesis "Study on the Microstructure and Mechanical Properties of Multi-directionally Forged Deformed Nano-SiCp / AZ91 Magnesium Matrix Composites" by Nie Kaibo of Harbin Institute of Technology in 2012 selected 60nm SiC particles as the reinforcement phase and the Mg-Al based AZ91 alloy as the matrix, and prepared 0.5, 1, 2, 3 vol.% SiCp / AZ91 magnesium matrix composites by combining the stir casting method and the ultrasonic dispersion method. The preparation process is as follows: Add the matrix AZ91D magnesium alloy into the crucible, protect it with a mixed gas of CO2 and SF6 after melting, adjust the magnesium melt to semi-solid state (580 - 650 °C) and conduct mechanical stirring. After the magnesium melt forms an ideal vortex state, quickly add the SiC nano-particles preheated to 550 °C and continue stirring for a certain time. After the semi-solid stirring is completed, raise the temperature of the magnesium melt to 700 °C and hold for a period of time. Take out the stirring paddle from the magnesium melt, introduce the preheated ultrasonic tool rod into the magnesium melt, and perform ultrasonic treatment on the magnesium melt at the set ultrasonic power. When the ultrasonic treatment time reaches the set time, remove the ultrasonic tool rod from the magnesium melt, and at the same time raise the melt temperature to 720 °C. Then pour the melt into the pouring mold preheated to 450 °C and solidify it under a pressure of 100 MPa. The as-cast yield strength, tensile strength and elongation of the prepared 1 vol.% - 60nm - SiCp / AZ91 composite are 80 MPa, 180 MPa and 6% respectively. After multi-directionally forging 6 passes at 400 °C, the yield strength, tensile strength and elongation are 190 MPa, 290 MPa and 9% respectively. In contrast, the yield strength, tensile strength and elongation of as-cast AZ91 are 70 MPa, 110 MPa and 2% respectively. After multi-directionally forging 6 passes at 400 °C, the yield strength, tensile strength and elongation are 150 MPa, 280 MPa and 8% respectively. It can be seen that the nano-SiC reinforced magnesium matrix composite is superior to the matrix alloy in terms of both strength and plasticity, and plastic deformation can further improve the mechanical properties of the composite. However, when the SiC volume fraction reaches 2 vol.%, due to the serious agglomeration of the reinforcement phase particles, the mechanical properties decrease significantly.In 2014, Afshin Matin et al. from Islamic Azad University of Iran published a paper in the journal Materials Science and Engineering A. They prepared two kinds of magnesium matrix composites, namely pure magnesium and AZ80 reinforced with 0.8, 1.3, 1.8 vol.% - 50nm SiC, by stir casting method. The preparation process was as follows: pure Mg or AZ80 melt was melted at 750 °C, SiC particles were added to the melt by stir casting method, the melt was held at 750 °C for 10 minutes, then mechanically stirred for 3 minutes, the melt was poured into a steel mold preheated to 450 °C, and solidified under a pressure of 150 MPa to reduce pores. The research found that: after adding nano-SiC, the as-cast grain size was significantly refined, the yield strength and tensile strength were significantly improved, and the elongation was maintained. The as-cast tensile strength of AZ80 was 80 MPa and the elongation was 3%. After adding 0.8 vol.% SiC, the tensile strength and elongation were increased to 180 MPa and 10% respectively. After adding 1.3 vol.% SiC, the tensile strength and elongation were 140 MPa and 3% respectively. When the volume fraction of SiC reached 1.8 vol.%, the tensile strength and elongation were 140 MPa and 2% respectively. The elongation showed a trend of increasing first and then decreasing with the increase of the volume fraction of nano-SiC particles. The decrease in plasticity was caused by the agglomeration of SiC particles. In 2022, P. Emadi et al. from Toronto Metropolitan University in Canada published an article in Journal of Alloys and Compounds. They comprehensively used powder metallurgy method and stir casting method to prepare 0, 0.02, 0.05, 0.1 wt.% - 60nm-SiC / Mg-11Al-0.6Zn-0.15Mn composites. The preparation method was as follows: SiC nanopowder and Al powder were ball milled at a speed of 300 rpm for 10 min, then the powder was pressed into a 5052 aluminum alloy tube with a wall thickness of 1.5 mm, and then hot extruded at 380 °C at a speed of 6.2 mm / s. The extruded bar was subjected to organic compound evaporation treatment at 300 °C for 3 h to prepare the SiC / Al intermediate. Then, a 1 kg AZ91E ingot was preheated at 250 °C, and then the ingot was placed in a crucible and heated to melt at 750 °C. A protective gas (CO2 + 0.5 vol.% SF6) was introduced at a flow rate of 4.7 L / min during the melting process. Then, the melt was mechanically stirred with a low-carbon steel paddle at a speed of 300 rpm, and the prepared SiC / Al intermediate was added at the same time and stirred for 30 s. Then, the melt at 720 °C was poured into a metal mold preheated to 540 °C. The addition of a small amount of nano-SiC would significantly refine the grains. The tensile strength and elongation of the matrix alloy without SiC were 100 MPa and 0.5% respectively. The tensile strength and elongation of the composite containing 0.1 wt.% SiC were 140 MPa and 0.8% respectively.In 2023, Kowit Ponhan, David Weston, and Karl Tassenberg from Khon Kaen University in Thailand and the University of Leicester in the UK published an article in Materials Today Communications. They prepared 0.0, 1.0, 1.5, 2.0 wt.%-50nm-SiC / AZ91D composites by comprehensively using intermediate pellet powder metallurgy technology, stir casting, and ultrasonic treatment. The preparation method is as follows: First, 44μm Mg powder and 50nm SiC particles are mixed by high-energy ball milling at 150 rpm for 20 hours. During the ball milling process, 2 wt.% stearic acid is added to prevent the adhesion of magnesium powder. After ball milling for 15 minutes, it is terminated for 15 minutes to prevent overheating. Then, the mixed powder is put into a small mold and cold-pressed into a cylindrical blank with a diameter of 30 mm under a pressure of 125 MPa. Then, an intermediate pellet is prepared by sintering at 415°C for 1 hour. 200 grams of AZ91D magnesium alloy is melted at 750°C, and the intermediate pellet is added through a funnel. To prevent the combustion and explosion of magnesium powder, the intermediate pellet is under the protection of 2 L / min argon gas during the whole addition process, and the intermediate pellet is pressed into the melt with a four-blade stirrer. After the intermediate pellet melts, it is stirred at a speed of 750 rpm for 10 minutes. Then, the melt is ultrasonically treated, the melt temperature is reduced from 750°C to 670°C, and then treated at a power of 90 W for 25 minutes. After that, the melt temperature is raised to 700°C and poured into a steel mold preheated to 350°C. The yield strength, tensile strength, and elongation of AZ91D are 80 MPa, 130 MPa, and 2% respectively. 1.5 wt.% SiC / AZ91 has the best tensile mechanical properties, with a yield strength, tensile strength, and elongation of 150 MPa, 190 MPa, and 4% respectively. From the literature research, it is found that the research and development of nano-SiC reinforced magnesium matrix composites is still in the laboratory research and development stage. Units such as Harbin Institute of Technology in China carried out relevant research and development earlier, and a series of research and development work has been carried out in European and American countries in the past five years.

[0008] Through the research on nano-SiC particle (particle size ≤ 100nm) reinforced magnesium matrix composites in the past ten years, it is found that the bottleneck in material preparation lies in the extremely high specific surface energy of nano-SiC particles, which are extremely easy to agglomerate under the action of van der Waals force. In order to promote the uniform dispersion of nano-SiC, the existing technical path is: powder metallurgy → stir casting → ultrasonic treatment → high-temperature casting. The above four processes are carried out in sequence. Powder metallurgy realizes the pre-dispersion of SiC particles, stir casting realizes the preliminary dispersion of SiC particles in the magnesium melt, ultrasonic treatment relies on the cavitation effect to break the agglomeration of nano-particles, and high-temperature casting realizes the rapid solidification of the magnesium melt, reducing the agglomeration of particles during the solidification process.

[0009] The technical difficulties not yet overcome by the prior art are as follows: (1) The addition amount of nano-SiC that can meet the requirements of both strength improvement and plasticity retention has not exceeded 2 wt.%. According to the rule of mixtures, the volume fraction of nano-SiC required for the elastic modulus of the magnesium matrix composite to reach 50 - 60 GPa is 15 - 27 wt.%. The reason is that when the addition amount of SiC is greater than 2 wt.%, the distance between nano-SiC particles in the melt becomes smaller, and the agglomeration driving force becomes larger. During the high-temperature casting process, without the action of an ultrasonic field or mechanical stirring, particle agglomeration occurs again. (2) The prior art can basically solve the dispersion of nano-SiC particles in the magnesium melt under laboratory conditions, but it still cannot meet the requirements of engineering applications. After the melt volume increases, on the one hand, the cavitation effect in the lower-layer melt far from the ultrasonic horn weakens. Therefore, the particle agglomeration in the lower layer of the melt cannot be effectively broken up. On the other hand, the addition of nano-SiC particles to the melt will significantly reduce the melt fluidity. In the prior art, in order to ensure sufficient fluidity of the melt during the casting process, the melt temperature is usually above 700 °C. In the case of a small melt volume (10 kg level), the influence of the melt temperature on the solidification rate is small. As the melt volume increases, for example, when it reaches more than 100 kg, the solidification rate will decrease significantly, the grain coarsening will be serious, and a large number of nano-particles will be pushed to the inter-dendrite regions and undergo serious agglomeration, thus seriously deteriorating the plasticity.

[0010] In summary, in order to develop a magnesium-based material with an elastic modulus greater than 50 GPa while maintaining the high plasticity of the magnesium alloy matrix, nano-SiC particles need to be selected. According to the rule of mixtures, the addition amount needs to reach 15 - 27 wt.% (9 - 18 vol.%). However, in the prior art, the addition amount of nano-SiC particles has not exceeded 2 wt.% while maintaining plasticity. The fundamental reasons are as follows: On the one hand, during the melt solidification process, without the action of external field stirring, the separated nano-particles will agglomerate again. On the other hand, in the prior art, in order to improve the fluidity of the melt after adding particles, the melt pouring temperature is relatively high. At the same time, the existing pouring method is to pour all the melt in a one-time liquid state, and the solidification method is to cool the entire melt as a whole, resulting in a low solidification rate, serious grain coarsening, and a large number of nano-particles being pushed to the inter-dendrite regions and undergoing serious agglomeration, thus seriously deteriorating the plasticity. In addition, the prior art cannot overcome the problem of nano-particle agglomeration under the condition of a large melt volume. The reason is also that the solidification rate of the melt is slow under the condition of a large melt volume, and the probability of particle sedimentation and agglomeration increases. Summary of the Invention

[0011] In view of the fact that the existing preparation technologies for nano-SiC reinforced magnesium-based materials cannot solve the problem of severe deterioration of plasticity after the elastic modulus is improved, and at the same time, in view of the fact that the existing technologies cannot solve the problem of severe agglomeration of nano-particles when the SiC content reaches 15-27 wt.% under the condition of a large melt volume, the present utility model provides a short-process melting and casting method and melting and casting equipment for an aluminum-containing magnesium-based material. The purpose of selecting a magnesium-aluminum-based magnesium alloy as the matrix in the present utility model is as follows: on the one hand, because these two magnesium alloy systems are the most mature and have the largest usage amount at present; on the other hand, in the powder metallurgy link, the powder metallurgy technology of aluminum-based materials is safer, that is, relatively safe SiC nano-powder and Al powder are used for mixing, avoiding the use of Mg powder with a greater risk of deflagration. In view of the problem that the slow solidification speed in the existing technology leads to the re-agglomeration of nano-particles in the solidification link, the present utility model changes the one-time solidification mode of all the melt into a layer-by-layer solidification mode of a small amount of melt, thereby greatly improving the solidification speed and limitedly solving the problem of particle agglomeration in the solidification link; in view of the problem of the lack of external field stirring in the solidification link in the existing technology, electromagnetic stirring and ultrasonic treatment are introduced into the water-cooled die liquid cavity while layer-by-layer solidification is carried out, so as to realize that the agglomerated particles are quickly solidified in the matrix after being dispersed. At the same time, due to the limited depth of the water-cooled die liquid cavity (the maximum depth is usually 100 mm), the entire melt is simultaneously subjected to a strong ultrasonic cavitation effect, and its ultrasonic dispersion effect is far better than the ultrasonic treatment of the entire melt in the existing technology. In short, the present utility model can significantly improve the solidification speed of the melt and at the same time significantly enhance the ultrasonic cavitation effect, and finally realize the uniform dispersion of nano-SiC particles. The prepared nano-SiC reinforced magnesium-based material has a high elastic modulus and strength and also has a certain plasticity. This utility model is of great significance for promoting the application of high-modulus magnesium-based materials in the fields of aerospace and weaponry.

[0012] The present utility model specifically includes the following contents:

[0013] A short-process melting and casting device includes an electrolytic magnesium liquid transfer package, an ultrasonic and electromagnetic-assisted layer-by-layer rapid solidification system, an infusion pipe, and an on-line heating furnace. The interior of the electrolytic magnesium liquid transfer package is provided with a heat preservation layer and a heating device, and a discharge port is arranged at the lower part of the electrolytic magnesium liquid transfer package; one end of the infusion pipe is connected to the discharge port; the ultrasonic and electromagnetic-assisted layer-by-layer rapid solidification system includes a water-cooled mold, a tractor, an electromagnetic stirring system, and an ultrasonic stirring system. The water-cooled mold includes a top cover, an inner pipe, and an outer pipe sleeved outside the inner pipe. A cooling cavity is formed between the inner pipe and the outer pipe. At least 20 spray water holes are evenly distributed along the circumferential direction at the lower part of the inner pipe. A cooling water inlet and a cooling water outlet are arranged on the outer pipe; the top cover is arranged at the top of the water-cooled mold, and an infusion pipe reserved hole, at least one ultrasonic horn reserved hole, and at least one feeding reserved port are arranged on the top cover; the tractor is arranged at the bottom of the water-cooled mold, and a cavity is formed by the top of the tractor and the inner wall of the inner pipe of the water-cooled mold; the electromagnetic stirring system includes at least one electromagnetic stirrer, and the electromagnetic stirrer is arranged at the upper part of the outer wall of the inner pipe of the water-cooled mold. The vertical setting position is: dividing the height of the inner pipe into four equal parts, and the electromagnetic stirrer is located within the range of the middle two quarter regions; the ultrasonic stirring system includes at least one ultrasonic transducer and at least one ultrasonic horn. One end of the ultrasonic horn is connected to the ultrasonic transducer, and the other end passes through the ultrasonic horn reserved hole and extends into the cavity formed by the inner wall of the inner pipe of the water-cooled mold and the top of the tractor; the other end of the infusion pipe passes through the infusion pipe reserved hole and extends into the cavity formed by the inner wall of the inner pipe of the water-cooled mold and the top of the tractor; the on-line heating furnace is arranged above the water-cooled mold, and the on-line heating furnace is provided with at least one heating channel.

[0014] Preferably, the heating channels are arranged in one-to-one correspondence with the feeding reserved ports on the top cover of the water-cooled mold.

[0015] Preferably, it further includes a protective gas storage tank, and a plurality of protective gas nozzles are further arranged on the top cover. The protective gas nozzles are connected to the protective gas storage tank.

[0016] The short-process melting and casting device disclosed by the utility model can be used for preparing aluminum-containing magnesium-based materials. The specific method includes the following steps:

[0017] (1) Preparation of powder metallurgy pre-dispersed bars: Mix SiC powder and Al powder, prepare a SiC / Al blank by powder metallurgy method, and then prepare a SiC / Al primary dispersed bar with a diameter of 10 mm to 20 mm by plastic forming method;

[0018] (2)Integrated treatment of molten magnesium pouring + pre-dispersed bar melting + external field-assisted layer-by-layer rapid solidification: In a protective gas atmosphere, pour the electrolytic molten magnesium in the transfer ladle of electrolytic molten magnesium into the cavity formed by the inner wall of the water-cooled mold and the top of the tractor. Start the electromagnetic stirring system to stir the melt. When a solidification shell is formed on the inner wall of the inner tube of the water-cooled mold, move the tractor downward to pull the solidified ingot downward, and turn on the cooling water of the water-cooled mold to cool the surface of the solidified ingot leaving the water-cooled mold. When a stable melt zone, mushy zone, and solidification zone are established in the water-cooled mold, immerse one end of the ultrasonic horn into the melt, and perform electromagnetic stirring and ultrasonic treatment synchronously; put the SiC / Al primary dispersion bar into the heating channel of the on-line heating furnace for preheating. While the tractor is descending, add the preheated SiC / Al primary dispersion bar into the melt zone in the water-cooled mold through the feeding reserved port on the top cover of the crystallization furnace at a certain speed, so that the SiC / Al primary dispersion bar melts and disperses in the melt, and the magnesium-based material containing aluminum is obtained after solidification.

[0019] Preferably, the SiC powder in step (1) is nano-SiC powder with a particle size ≤ 100 nm; or, the SiC powder is nano-scale SiC powder with a particle size ≤ 100 nm, and / or micron-scale SiC powder with a particle size ≥ 1 μm, and / or sub-micron-scale SiC powder with a particle size between 1 μm and 100 nm.

[0020] Preferably, the mixing time of the SiC powder and the Al powder in step (1) is 6 - 24 h; and / or, the powder metallurgy method includes cold isostatic pressing and vacuum sintering, the plastic forming method includes hot extrusion, the pressure of the cold isostatic pressing is 100 - 250 MPa, and the pressure holding time is 10 - 20 s; and / or, the temperature of the vacuum sintering is 350 - 550 °C, the heat preservation time is 3 - 6 hours, the vacuum degree during the sintering process is (1 - 3) × 10-2 Pa, and the furnace is cooled to room temperature after the vacuum sintering ends; and / or, the temperature of the hot extrusion is 350 - 550 °C, and the extrusion ratio is 50 - 150.

[0021] Preferably, in step (2), the protective gas is a mixed gas of Ar and tetrafluoroethane, the volume ratio of Ar to tetrafluoroethane in the mixed gas is (5-7):1, and / or, the flow rate of the protective gas is 2-4 L / min; and / or, the temperature of the electrolytic magnesium liquid is 50-80 °C higher than the liquidus of the Mg-Al alloy system; and / or, the pouring rate of the electrolytic magnesium liquid is 5-20 kg / min; and / or, the operating frequency of the excitation coil of the electromagnetic stirring system is 10-50 Hz, and the alternating current intensity of the electromagnetic stirring system is 100-300 A; and / or, the descending speed of the tractor is 10-200 mm / min; and / or, the heating temperature of the heating channel of the on-line heating furnace is 550-650 °C; and / or, the speed of adding the preheated SiC / Al pre-dispersed bar into the water-cooled mold is 50-500 mm / min; and / or, the flow rate of the cooling water is 4-12 t / h; and / or, the heating temperature of the ultrasonic horn is 600-650 °C, and the immersion depth into the melt is 20-80 mm; and / or, the power of the ultrasonic treatment is 0.5-6 Kw.

[0022] The aluminum-containing magnesium-based material prepared by using this device can be applied in automobiles, electronics, rail transit, or mechanical equipment.

[0023] The beneficial effects of the present utility model are as follows:

[0024] (1) The short-process melting and casting device disclosed by the present utility model can realize the integrated treatment of metal liquid pouring + melting of pre-dispersed extruded materials + rapid solidification layer by layer with external field assistance, greatly shortening the melting and casting process and improving the production efficiency.

[0025] (2) The method disclosed by the present utility model can effectively solve the problem of re-agglomeration of the already dispersed particles caused by the lack of external field assistance in the melt solidification process of the prior art through ultrasonic and electromagnetic-assisted layer-by-layer rapid solidification. At the same time, it solves the problem of slow solidification speed caused by the relatively high melt temperature and the one-time solidification of the entire melt. A slow solidification speed will cause the already dispersed particles to be pushed to the grain boundaries by numerous growing grains and agglomerate. The present utility model first prepares a SiC / Al pre-dispersed bar by powder metallurgy, and then conducts an integrated treatment of magnesium liquid pouring + melting of the pre-dispersed extruded material + external field-assisted layer-by-layer rapid solidification. Under the action of ultrasonic cavitation and electromagnetic stirring, and at the same time under the action of a water-cooled mold, Al and SiC are quickly and evenly distributed. At the same time, the dispersed SiC particles quickly enter the mushy zone to achieve layer-by-layer rapid solidification, effectively solving the problems of agglomeration caused by the lack of external field assistance and the agglomeration of particles pushed to the grain boundaries by the matrix grains due to slow solidification speed during the solidification process of the prior art. In order to prevent the melt from oxidizing, a protective gas is distributed in the water-cooled mold to protect the melt surface with gas throughout the process. After testing, the yield strength of the aluminum-containing magnesium-based material prepared by the present utility model is 250 - 300 MPa, the tensile strength is 290 - 350 MPa, the elongation is 3 - 8%, and the elastic modulus is 50 - 60 GPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of the short-process melting and casting device disclosed by the present utility model;

[0027] Among them, 3 - SiC / Al pre-dispersed bar, 10 - melt zone, 11 - mushy zone, 12 - solidification zone, 13 - water-cooled mold, 14 - electromagnetic stirring system, 15 - cooling water, 16 - tractor, 17 - ultrasonic horn, 18 - ultrasonic transducer, 20 - electrolytic magnesium liquid transfer package, 21 - on-line heating furnace. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The present utility model will be described in detail below in conjunction with the drawings and specific embodiments. The following embodiments shown do not limit the content of the utility model recorded in the claims in any way. In addition, the entire content of the constitution shown in the following embodiments is not limited to what is necessary for the solution of the utility model recorded in the claims.

[0029] Refer to the attached Figure 1, A short-process melting and casting device, comprising an electrolytic magnesium liquid transfer package 20, an ultrasonic and electromagnetic-assisted layer-by-layer rapid solidification system, an infusion pipe, and an on-line heating furnace 21. A heat preservation layer and a heating device are arranged inside the electrolytic magnesium liquid transfer package 20, and a discharge port is arranged at the lower part of the electrolytic magnesium liquid transfer package 20; one end of the infusion pipe is connected to the discharge port; the ultrasonic and electromagnetic-assisted layer-by-layer rapid solidification system includes a water-cooled mold 13, a tractor 16, an electromagnetic stirring system 14, and an ultrasonic stirring system. The water-cooled mold 13 includes a top cover, an inner pipe, and an outer pipe sleeved outside the inner pipe. A cooling cavity is formed between the inner pipe and the outer pipe. At least 20 spray water holes are evenly distributed along the circumferential direction at the lower part of the inner pipe. A cooling water inlet and a cooling water outlet are arranged on the outer pipe; the top cover is arranged at the top of the water-cooled mold, and an infusion pipe reserved hole, at least one ultrasonic horn reserved hole, and at least one feeding reserved port are arranged on the top cover; the tractor 16 is arranged at the bottom of the water-cooled mold, and a cavity is formed by the top of the tractor 16 and the inner wall of the inner pipe of the water-cooled mold; the electromagnetic stirring system 14 includes at least one electromagnetic stirrer, and the electromagnetic stirrer is arranged at the upper part of the outer wall of the inner pipe of the water-cooled mold. The vertical setting position is: dividing the height of the inner pipe into four equal parts, and the electromagnetic stirrer is located within the range of the middle two quarter regions; the ultrasonic stirring system includes at least one ultrasonic transducer 18 and at least one ultrasonic horn 17. One end of the ultrasonic horn 17 is connected to the ultrasonic transducer 18, and the other end passes through the ultrasonic horn reserved hole and extends into the cavity formed by the inner wall of the inner pipe of the water-cooled mold and the top of the tractor 16; the other end of the infusion pipe passes through the infusion pipe reserved hole and extends into the cavity formed by the inner wall of the inner pipe of the water-cooled mold and the top of the tractor 16; the on-line heating furnace 21 is arranged above the water-cooled mold, and the on-line heating furnace 21 is provided with at least one heating channel.

[0030] In an embodiment of the present invention, the heating channels are arranged in one-to-one correspondence with the feeding reserved ports on the top cover of the water-cooled mold.

[0031] In an embodiment of the present invention, a protective gas storage tank is further included, and a plurality of protective gas nozzles are further arranged on the top cover. The protective gas nozzles are connected to the protective gas storage tank.

[0032] A short-process melting and casting method for an aluminum-containing magnesium-based material. The melting and casting method preferably uses the short-process melting and casting device disclosed in the present invention. The method includes the following steps:

[0033] (1) Preparation of powder metallurgy pre-dispersed bar: Mix SiC powder and Al powder for 6 - 24 h, and prepare SiC / Al blank by powder metallurgy method. The SiC powder is nano-SiC powder; or, the SiC powder is nano-SiC powder, and micron or sub-micron SiC powder; then prepare SiC / Al primary dispersion bar with a diameter of 10 mm - 20 mm by plastic forming method. The mixing method is: First, mix nano-SiC powder and Al powder to obtain a mixed powder, and then mix the mixed powder with micron or sub-micron SiC powder. The powder metallurgy method includes cold isostatic pressing and vacuum sintering, and the plastic forming method includes hot extrusion. The pressure of cold isostatic pressing is 100 - 250 MPa, and the pressure holding time is 10 - 20 s; the temperature of vacuum sintering is 350 - 550 °C, and the heat preservation time is 3 - 6 hours. The vacuum degree during the sintering process is (1 - 3)×10 -2 Pa. After the vacuum sintering is completed, the furnace is cooled to room temperature; the temperature of hot extrusion is 350 - 550 °C, the extrusion ratio is 50 - 150, and the diameter of the extruded bar is 10 mm - 20 mm.

[0034] (2)Integrated treatment of magnesium melt casting + pre-dispersed extrusion material melting + external field-assisted layer-by-layer rapid solidification: Using an ultrasonic and electromagnetic-assisted melt layer-by-layer rapid solidification system, high-temperature electrolytic magnesium is injected into the cavity formed by the inner wall of the water-cooled mold and the top surface of the tractor 16 through the electrolytic magnesium transfer package 20. The temperature of the electrolytic magnesium liquid is 50 - 80 °C higher than the liquidus of the Mg-Al alloy system, and the casting rate is 5 - 20 kg / min. Then, start the electromagnetic stirring system 14 to stir the melt. The working frequency of the excitation coil of the electromagnetic stirring system 14 is 10 - 50 Hz, and the alternating current intensity is 100 - 300 A. After a solidification shell is formed in the water-cooled mold, the tractor 16 starts to pull the solidification zone 12 downward at a speed of 10 - 200 mm / min. Open the cooling water of the water-cooled mold and set the flow rate to 4 - 12 t / h. The cooling water fills the cooling cavity between the inner pipe and the outer pipe of the water-cooled mold. There is a water outlet at the lower part of the inner wall of the inner pipe of the water-cooled mold, and numerous water columns are formed through the water outlet to water-cool the surface of the ingot blank solidification zone 12. When a stable melt zone 10, mushy zone 11, and solidification zone 12 are established in the water-cooled mold, one end of the ultrasonic horn 17 with a heating temperature of 600 - 650 °C is immersed in the melt, and the immersion depth is 20 - 80 mm. Start the ultrasonic transducer 18, and simultaneously perform electromagnetic stirring and ultrasonic treatment, and control the power of the ultrasonic treatment to be 0.5 - 6 kW. Subsequently, the SiC / Al pre-dispersed extrusion material 3 heated through the heating channel of the online heating furnace 21 is added to the melt zone 10 at a speed of 50 - 500 mm / min. The heating temperature of the heating channel is 550 - 650 °C. After the extrusion material melts, Al and SiC enter the melt zone 10. Under the action of ultrasonic cavitation and electromagnetic stirring, and at the same time under the action of the water-cooled mold 13, Al and SiC are quickly and evenly distributed. At the same time, the dispersed SiC particles quickly enter the mushy zone 11 to achieve layer-by-layer rapid solidification, effectively solving the problems of agglomeration caused by the lack of external field assistance during the solidification process in the prior art and the agglomeration of particles being pushed to the grain boundaries by the matrix grains due to slow solidification speed. In order to prevent the melt from oxidizing, protective gas nozzles are evenly distributed above the water-cooled mold to protect the surface of the melt with a protective gas. The protective gas is a mixed gas of Ar and tetrafluoroethane, and the mixing ratio of Ar and tetrafluoroethane is (5 - 7):1, and the flow rate of the protective gas is 2 - 4 L / min. The aluminum-containing magnesium-based material prepared by this method has excellent properties and can be used in fields such as automobiles, electronics, rail transit, or mechanical equipment, etc.

[0035] Example 1

[0036] A short-process melting and casting method for an aluminum-containing magnesium-based material with 8 wt.% SiC content. The melting and casting method of this example is realized by using the short-process melting and casting device disclosed by the present invention. This method includes the following steps:

[0037] (1) Preparation of SiC / Al pre-dispersed extrusion material 3: Mix nano-SiC powder and Al powder for 6 h. After mixing, obtain the SiC / Al pre-dispersed extrusion material 3 through cold isostatic pressing, vacuum sintering, and hot extrusion; the pressure of cold isostatic pressing is 100 MPa, and the pressure holding time is 10 s; the temperature of vacuum sintering is 350 °C, the heat preservation time is 3 h, and the vacuum degree during sintering is 1×10 -2 Pa, and after vacuum sintering, cool the furnace to room temperature; the temperature of hot extrusion is 350 °C, and the extrusion ratio is 50.

[0038] (2) Magnesium liquid casting + melting of pre-dispersed extrusion material + integrated treatment of external field-assisted layer-by-layer rapid solidification: Using an ultrasonic and electromagnetic-assisted melt layer-by-layer rapid solidification system, inject high-temperature electrolytic magnesium into the cavity formed by the inner wall of the water-cooled mold and the top surface of the tractor 16 through 20. The temperature of the electrolytic magnesium liquid is 50 °C higher than the liquidus of the Mg-Al alloy system, and the casting rate is 5 kg / min; and start the electromagnetic stirring system 14 to stir the melt. The working frequency of the excitation coil of the electromagnetic stirring system 14 is 10 Hz, and the alternating current intensity is 100 A. After a solidification shell is formed in the water-cooled mold, the tractor 16 starts to pull the solidification zone 12 downward at a speed of 10 mm / min. Open the cooling water of the water-cooled mold and set the flow rate to 4 t / h. The cooling water fills the cooling cavity between the inner pipe and the outer pipe of the water-cooled mold. There is a water outlet under the inner wall of the inner pipe of the water-cooled mold, and numerous water columns are formed through the water outlet to water-cool the surface of the ingot blank solidification zone 12. When a stable melt zone 10, mushy zone 11, and solidification zone 12 are established in the water-cooled mold, immerse one end of the ultrasonic horn 17 with a heating temperature of 600 °C into the melt, and the immersion depth is 20 mm. Start the ultrasonic transducer 18, and perform electromagnetic stirring and ultrasonic treatment synchronously, and control the power of the ultrasonic treatment to be 0.5 Kw; Subsequently, add the SiC / Al pre-dispersed extrusion material 3 heated through the heating channel of the online heating furnace 21 into the melt zone 10 at a speed of 50 mm / min. The heating temperature of the heating channel is 550 °C. After the extrusion material melts, Al and SiC enter the melt zone 10. Under the action of ultrasonic cavitation and electromagnetic stirring, and at the same time under the action of the water-cooled mold 13, Al and SiC are quickly and evenly distributed. At the same time, the dispersed SiC particles quickly enter the mushy zone 11 to achieve layer-by-layer rapid solidification, effectively solving the problems of agglomeration caused by the lack of external field assistance during the solidification process in the prior art and the agglomeration of particles being pushed to the grain boundaries by the matrix grains due to slow solidification speed. In order to prevent the melt from oxidizing, protective gas nozzles are evenly distributed above the water-cooled mold to protect the surface of the melt throughout the process. The protective gas is a mixed gas of Ar and tetrafluoroethane, and the mixing ratio of Ar and tetrafluoroethane is 5:1, and the flow rate of the protective gas is 2 L / min. After testing, the yield strength of the aluminum-containing magnesium-based material prepared by the present utility model is 250 MPa, the tensile strength is 291 MPa, the elongation is 5%, and the elastic modulus is 50 GPa.

[0039] Example 2

[0040] A melting and casting method for an aluminum-magnesium-based material with 11 wt.% SiC content. The melting and casting method of this example is realized by using the short-process melting and casting device disclosed by the present utility model. The method comprises the following steps:

[0041] (1) Prepare the SiC / Al pre-dispersed extrusion material 3: First, mix the nano-SiC powder and the Al powder to obtain a mixed powder, and then mix the mixed powder with the micro-SiC powder, and control the total mixing time to be 24 h. After mixing, through cold isostatic pressing, vacuum sintering and hot extrusion, obtain the SiC / Al pre-dispersed extrusion material 3; the pressure of cold isostatic pressing is 250 MPa, and the pressure holding time is 20 s; the temperature of vacuum sintering is 550 °C, and the heat preservation time is 6 hours. The vacuum degree during the sintering process is 3×10 -2 Pa. After the vacuum sintering is completed, the furnace is cooled to room temperature; the temperature of hot extrusion is 550 °C, and the extrusion ratio is 150.

[0042] (2)Integrated treatment of magnesium liquid pouring + pre-dispersed extrusion material melting + external field-assisted layer-by-layer rapid solidification: Using an ultrasonic and electromagnetic-assisted melt layer-by-layer rapid solidification system, high-temperature electrolytic magnesium is injected into the cavity formed by the inner wall of the water-cooled mold and the top surface of the tractor 16 through the electrolytic magnesium transfer package 20. The temperature of the electrolytic magnesium liquid is 80 °C higher than the liquidus of the Mg-Al alloy system, and the pouring rate is 20 kg / min; then start the electromagnetic stirring system 14 to stir the melt. The working frequency of the excitation coil of the electromagnetic stirring system 14 is 50 Hz, and the alternating current intensity is 300 A. After a solidification shell is formed in the water-cooled mold, the tractor 16 starts to pull the solidification zone 12 downward at a speed of 200 mm / min. Turn on the cooling water of the water-cooled mold and set the flow rate to 12 t / h. The cooling water fills the cooling cavity between the inner tube and the outer tube of the water-cooled mold. There is a water outlet at the lower part of the inner wall of the inner tube of the water-cooled mold, and numerous water columns are formed through the water outlet to water-cool the surface of the ingot blank solidification zone 12. When a stable melt zone 10, mushy zone 11, and solidification zone 12 are established in the water-cooled mold, one end of the ultrasonic horn 17 with a heating temperature of 650 °C is immersed in the melt, and the immersion depth is 80 mm. Start the ultrasonic transducer 18, and perform electromagnetic stirring and ultrasonic treatment simultaneously, controlling the power of the ultrasonic treatment to be 6 Kw; then, add the SiC / Al pre-dispersed extrusion material 3 heated through the heating channel of the online heating furnace 21 into the melt zone 10 at a speed of 500 mm / min. The heating temperature of the heating channel is 650 °C. After the extrusion material melts, Al and SiC enter the melt zone 10. Under the action of ultrasonic cavitation and electromagnetic stirring, and at the same time under the action of the water-cooled mold 13, Al and SiC are quickly and evenly distributed. At the same time, the dispersed SiC particles quickly enter the mushy zone 11 to achieve layer-by-layer rapid solidification, effectively solving the problems of agglomeration caused by the lack of external field assistance during the solidification process in the prior art and the agglomeration of particles being pushed to the grain boundaries by the matrix grains due to slow solidification speed. To prevent the melt from oxidizing, protective gas nozzles are evenly distributed above the water-cooled mold to protect the surface of the melt throughout the process. The protective gas is a mixed gas of Ar and tetrafluoroethane, and the mixing ratio of Ar and tetrafluoroethane is 7:1, and the flow rate of the protective gas is 4 L / min. After testing, the yield strength of the aluminum-containing magnesium-based material prepared by the present utility model is 298 MPa, the tensile strength is 350 MPa, the elongation is 4.1%, and the elastic modulus is 52 GPa.

[0043] Example 3

[0044] A melting and casting method for an aluminum-magnesium-based material with a SiC content of 15 wt.%, comprising the following steps:

[0045] (1) Preparation of SiC / Al pre-dispersed extruded material 3: First, mix the nano-SiC powder with the Al powder to obtain a mixed powder, and then mix the mixed powder with the sub-micron SiC powder, controlling the total mixing time to be 15 h. After mixing, through cold isostatic pressing, vacuum sintering and hot extrusion, the SiC / Al pre-dispersed extruded material 3 is obtained; the pressure of cold isostatic pressing is 150 MPa and the pressure holding time is 15 s; the temperature of vacuum sintering is 400 °C, the heat preservation time is 4 hours, and the vacuum degree during sintering is 2×10 -2 Pa. After the vacuum sintering is completed, the furnace is cooled to room temperature; the temperature of hot extrusion is 400 °C and the extrusion ratio is 100.

[0046] (2)Integrated treatment of molten magnesium pouring + pre-dispersed extrusion material melting + external field-assisted layer-by-layer rapid solidification: Using an ultrasonic and electromagnetic-assisted melt layer-by-layer rapid solidification system, high-temperature electrolytic magnesium is injected into the cavity formed by the inner wall of the water-cooled mold and the top surface of the tractor 16 through the electrolytic magnesium transfer package 20. The temperature of the electrolytic magnesium liquid is 60 °C higher than the liquidus of the Mg-Al alloy system, and the pouring rate is 10 kg / min. Then, start the electromagnetic stirring system 14 to stir the melt. The working frequency of the excitation coil of the electromagnetic stirring system 14 is 20 Hz, and the alternating current intensity is 150 A. After a solidification shell is formed in the water-cooled mold, the tractor 16 starts to pull the solidification zone 12 downward at a speed of 100 mm / min. Turn on the cooling water of the water-cooled mold and set the flow rate to 8 t / h. The cooling water fills the cooling cavity between the inner pipe and the outer pipe of the water-cooled mold. There is a water outlet at the lower part of the inner wall of the inner pipe of the water-cooled mold, and numerous water columns are formed through the water outlet to water-cool the surface of the ingot blank solidification zone 12. When a stable melt zone 10, mushy zone 11, and solidification zone 12 are established in the water-cooled mold, one end of the ultrasonic horn 17 with a heating temperature of 620 °C is immersed in the melt to a depth of 40 mm. Start the ultrasonic transducer 18, and perform electromagnetic stirring and ultrasonic treatment synchronously, controlling the power of the ultrasonic treatment to be 2 Kw. Subsequently, the SiC / Al pre-dispersed extrusion material 3 heated through the heating channel of the online heating furnace 21 is added to the melt zone 10 at a speed of 200 mm / min. The heating temperature of the heating channel is 600 °C. After the extrusion material melts, Al and SiC enter the melt zone 10. Under the action of ultrasonic cavitation and electromagnetic stirring, and at the same time under the action of the water-cooled mold 13, Al and SiC are quickly and evenly distributed. At the same time, the dispersed SiC particles quickly enter the mushy zone 11 to achieve layer-by-layer rapid solidification, effectively solving the problems of agglomeration caused by the lack of external field assistance during the solidification process in the prior art and the agglomeration of particles being pushed to the grain boundaries by the matrix grains due to slow solidification speed. To prevent melt oxidation, protective gas nozzles are evenly distributed above the water-cooled mold to protect the melt surface throughout the process. The protective gas is a mixed gas of Ar and tetrafluoroethane, and the mixing ratio of Ar and tetrafluoroethane is 6:1, and the flow rate of the protective gas is 3 L / min. After testing, the yield strength of the aluminum-containing magnesium-based material prepared by the present utility model is 290 MPa, the tensile strength is 360 MPa, the elongation is 3.2%, and the elastic modulus is 55 GPa.

[0047] Example 4

[0048] A melting and casting method for an aluminum-magnesium-based material with a SiC content of 21 wt.%. The melting and casting method of this example is realized by using the short-process melting and casting device disclosed by the present utility model. This method includes the following steps:

[0049] (1) Preparation of SiC / Al pre-dispersed extruded material 3: Mix nano-SiC powder and Al powder for 20 h. After mixing, through cold isostatic pressing, vacuum sintering and hot extrusion, obtain SiC / Al pre-dispersed extruded material 3; the pressure of cold isostatic pressing is 220 MPa, and the pressure holding time is 18 s; the temperature of vacuum sintering is 500 °C, the heat preservation time is 5 hours, and the vacuum degree during sintering is 2.5×10 -2 Pa. After vacuum sintering, cool the furnace to room temperature; the temperature of hot extrusion is 500 °C, and the extrusion ratio is 120.

[0050] (2)Integrated treatment of molten magnesium pouring + pre-dispersed extrusion material melting + external field-assisted layer-by-layer rapid solidification: Using an ultrasonic and electromagnetic-assisted melt layer-by-layer rapid solidification system, high-temperature electrolytic magnesium is injected into the cavity formed by the inner wall of the water-cooled mold and the top surface of the tractor 16 through the electrolytic magnesium transfer package 20. The temperature of the electrolytic magnesium liquid is 70 °C higher than the liquidus of the Mg-Al alloy system, and the pouring rate is 18 kg / min. Then, start the electromagnetic stirring system 14 to stir the melt. The working frequency of the excitation coil of the electromagnetic stirring system 14 is 35 Hz, and the alternating current intensity is 250 A. After a solidification shell is formed in the water-cooled mold, the tractor 16 starts to pull the solidification zone 12 downward at a speed of 180 mm / min. Turn on the cooling water of the water-cooled mold and set the flow rate to 10 t / h. The cooling water fills the cooling cavity between the inner tube and the outer tube of the water-cooled mold. There are water outlets arranged below the inner wall of the inner tube of the water-cooled mold, and numerous water columns are formed through the water outlets to cool the surface of the ingot blank solidification zone 12. When a stable melt zone 10, mushy zone 11, and solidification zone 12 are established in the water-cooled mold, one end of the ultrasonic horn 17 with a heating temperature of 635 °C is immersed in the melt, and the immersion depth is 60 mm. Start the ultrasonic transducer 18, and perform electromagnetic stirring and ultrasonic treatment simultaneously, controlling the power of the ultrasonic treatment to be 5 Kw. Subsequently, the SiC / Al pre-dispersed extrusion material 3 heated through the heating channel of the online heating furnace 21 is added to the melt zone 10 at a speed of 350 mm / min. The heating temperature of the heating channel is 600 °C. After the extrusion material melts, Al and SiC enter the melt zone 10. Under the action of ultrasonic cavitation and electromagnetic stirring, and at the same time under the action of the water-cooled mold 13, Al and SiC are quickly and evenly distributed. At the same time, the dispersed SiC particles quickly enter the mushy zone 11, realizing layer-by-layer rapid solidification, effectively solving the problems of agglomeration caused by the lack of external field assistance during the solidification process in the prior art and the agglomeration of particles being pushed to the grain boundaries by the matrix grains due to slow solidification speed. In order to prevent the melt from oxidizing, protective gas nozzles are evenly distributed above the water-cooled mold to protect the melt surface throughout. The protective gas is a mixed gas of Ar and tetrafluoroethane, and the mixing ratio of Ar and tetrafluoroethane is 6.5:1, and the flow rate of the protective gas is 3.5 L / min. After testing, the yield strength of the aluminum-containing magnesium-based material prepared by the present utility model is 310 MPa, the tensile strength is 395 MPa, the elongation is 2.1%, and the elastic modulus is 60 GPa.

[0051] Example 5

[0052] Short process preparation method for 5vol.%-60nm SiC / Mg-13%Al magnesium-based material 100mm diameter extrusion bar, and the specific preparation process is as follows:

[0053] To prepare 100 kg of magnesium-based material extrusion rods with a designed composition of 5 vol.% - 60 nm SiC / Mg - 13% Al, Table 3 shows the raw material batching table. Weigh the raw materials according to the batching table and polish the surface of the magnesium ingots.

[0054] Table 3. Raw Material Batching Table

[0055] Raw material category Input quantity kg 60nm - SiC powder 8 10μm - Al powder 12 Electrolytic magnesium liquid 80 Total 100

[0056] Step 1: First, mix 60 nm SiC powder and 10 μm Al powder for 6 hours, then perform cold isostatic pressing on the mixed powder at a pressure of 250 MPa for a holding time of 20 s to obtain a blank with a size of Φ100 mm × 210 mm; perform vacuum sintering treatment on the blank at a sintering temperature of 550 °C for 4 hours, and cool it to room temperature in the furnace. The vacuum degree during the sintering process is 2×10 -2 Pa to obtain a blank with a size of Φ100 mm × 210 mm; reheat the blank to 550 °C and then perform hot extrusion. The temperature of the extrusion cylinder is 550 °C and the extrusion ratio is 144 to obtain Φ10 mm pre-dispersed extrusion rods 3.

[0057] Step 2: To prevent the melt from oxidation, protective gas nozzles are evenly distributed above the water-cooled mold 13 to conduct gas protection on the surface of the melt 10 throughout the process. The protective gas is a mixed gas of Ar and tetrafluoroethane (mixing ratio 6:1), with a flow rate of 3 L / min. The ultrasonic and electromagnetic-assisted layer-by-layer rapid solidification system selects a water-cooled mold 13 with an inner diameter of Φ350 mm. The electrolytic magnesium liquid at 680 °C is injected into the cavity formed by the inner wall of the water-cooled mold 13 and the top surface of the traction device 16 at a speed of 10 kg / min through the electrolytic magnesium liquid transfer package 20. Then, the electromagnetic stirring system 14 is started. The working frequency of the excitation coil of the electromagnetic stirring system is 50 Hz, and the alternating current intensity is 300 A to stir the melt 10. After the solidification shell 12 is formed in the water-cooled mold, the traction device starts to pull the solidification zone 12 downward, with a descent speed of the traction device of 50 mm / min. The water-cooling valve of the water-cooled mold is opened, and the cooling water 15 fills the inner cavity of the water-cooled mold 13. Numerous water columns are formed through the water outlet below the inner wall of the water-cooled mold 13 to conduct water cooling on the surface of the ingot blank solidification zone 12, with a cooling water flow rate of 4 t / h. When a stable melt zone 10, mushy zone 11, and solidification zone 12 are established in the water-cooled mold 13, one end of the ultrasonic horn 17 heated to 600 °C is immersed in the melt 10 with an immersion depth of 20 mm. The ultrasonic transducer 18 is started with an ultrasonic power of 5 Kw, and electromagnetic stirring and ultrasonic treatment are carried out synchronously. Subsequently, the SiC / Al pre-dispersed extrusion material 3 heated to 650 °C online is added to the melt zone 10 at a speed of 300 mm / min. After the extrusion material 3 melts, Al and SiC enter the melt zone 10. Under the action of ultrasonic cavitation and electromagnetic stirring, and at the same time under the action of the water-cooled mold 13, Al and SiC are quickly and evenly distributed. At the same time, the dispersed SiC particles quickly enter the mushy zone 11 to achieve layer-by-layer rapid solidification, effectively solving the problems of agglomeration caused by the lack of external field assistance during the solidification process in the prior art and the agglomeration of particles being pushed to the grain boundaries by the matrix grains due to the slow solidification speed; finally, a 5vol.%-60nmSiC / Mg-13%Al ingot with a size of Φ350 mm×500 mm is obtained.

[0058] Step 3: The Φ350 mm×500 mm magnesium-based material ingot is kept at 400 °C for 4 hours, and immediately transferred to a Φ420 mm extrusion cylinder after being taken out of the furnace. The temperature of the extrusion cylinder is 380 °C, and the speed of the extrusion rod is 25 mm / min to obtain a Φ100 mm extrusion bar. The yield strength, tensile strength, and elongation of the magnesium-based material extrusion bar are 249 MPa, 295 MPa, and 5% respectively, and the elastic modulus reaches 50 GPa.

[0059] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present utility model. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present utility model. Therefore, the present utility model will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A short process melting and casting device, characterized in that: It includes an electrolytic magnesium liquid transfer bag, an ultrasonic and electromagnetic assisted layer-by-layer rapid solidification system, an infusion tube, and an online heating furnace. The electrolytic magnesium liquid transfer bag is provided with an insulation layer and a heating device inside, and a discharge port is provided at the lower part of the electrolytic magnesium liquid transfer bag; one end of the infusion tube is connected to the discharge port; The ultrasonic and electromagnetic assisted layer-by-layer rapid solidification system comprises a water-cooled mold, a tractor, an electromagnetic stirring system, and an ultrasonic stirring system. The water-cooled mold comprises a top cover, an inner tube, and an outer tube sleeved outside the inner tube, a cooling cavity is formed between the inner tube and the outer tube, at least 20 spray outlet holes are evenly distributed along the circumferential direction at the lower part of the inner tube, and a cooling water inlet and a cooling water outlet are arranged on the outer tube; the top cover is arranged on the top of the water-cooled mold, and a reserved hole for an infusion tube, at least one reserved hole for an ultrasonic horn, and at least one reserved opening for feeding are arranged on the top cover; the tractor is arranged at the bottom of the water-cooled mold, and the top of the tractor and the inner wall of the inner tube of the water-cooled mold form a mold cavity; the electromagnetic stirring system includes at least one electromagnetic stirrer, which is arranged on the upper part of the outer wall of the inner tube of the water-cooling mold, and the vertical setting position is: the height of the inner tube is divided into four equal parts, and the electromagnetic stirrer is located within the range of the two middle quarters; the ultrasonic stirring system includes at least one ultrasonic transducer and at least one ultrasonic amplitude transformer, one end of the ultrasonic amplitude transformer is connected to the ultrasonic transducer, and the other end passes through the reserved hole of the ultrasonic amplitude transformer and extends into the inner wall of the inner tube of the water-cooling mold and the cavity surrounded by the top of the tractor; the other end of the infusion tube passes through the reserved hole of the infusion tube and extends into the inner wall of the inner tube of the water-cooling mold and the cavity surrounded by the top of the tractor; The online heating furnace is arranged above the water-cooling mold, and the online heating furnace is provided with at least one heating channel.

2. A short process melting and casting device according to claim 1, characterized in that: The heating channel is arranged in one-to-one correspondence with the reserved feeding opening on the water-cooling mold top cover.

3. The short-process melting and casting device according to any one of claims 1 to 2, characterized in that: It also includes a protective gas storage tank. The top cover is also provided with a plurality of protective gas nozzles, and the protective gas nozzles are connected to the protective gas storage tank.

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