阅读说明：本技术 一种超声处理与Bi复合细化亚共晶Al-Mg2Si合金组织的方法 (Ultrasonic treatment and Bi composite refined hypoeutectic Al-Mg2Method for forming Si alloy structure ) 是由 姜峰 邱克强 王鑫 武晓峰 于 2020-04-27 设计创作，主要内容包括：本发明公开了一种超声处理与Bi复合细化亚共晶Al-Mg<Sub>2</Sub>Si合金组织的方法,涉及铝合金熔炼与铸造技术。本发明通过采用金属Bi为变质剂细化亚共晶Al-Mg<Sub>2</Sub>Si合金中的共晶Mg<Sub>2</Sub>Si增强体,使其由板片状、针状结构变成珊瑚状、纤维状和颗粒状,并通过超声处理消除铸态亚共晶Al-Mg<Sub>2</Sub>Si合金在变质过程中产生的气体,减少缩孔、缩松和金属Bi的偏析缺陷,同时细化初生铝(α-Al)晶粒尺寸,使其结构形貌由粗大的树枝晶转变为等轴晶,进而提高亚共晶Al-Mg<Sub>2</Sub>Si合金的综合力学性能。本发明公开保护的金属Bi与超声复合处理是一项既达到细化晶粒、除气、除杂、改善疏松、偏析,又能有效提高铸锭品质,该方法操作简单、成本低廉、绿色环保,适于推广与应用。(The invention discloses an ultrasonic treatment and Bi composite refined hypoeutectic Al-Mg 2 A method of Si alloy structure relates to aluminum alloy smelting and casting technology. The invention refines hypoeutectic Al-Mg by adopting metal Bi as a modifier 2 Eutectic Mg in Si alloys 2 Si reinforcement, changing the plate-shaped and needle-shaped structure into coral-shaped, fiber-shaped and granular, and eliminating the cast hypoeutectic Al-Mg by ultrasonic treatment 2 Gas generated in the modification process of the Si alloy reduces shrinkage cavity, shrinkage porosity and segregation defects of metal Bi, and simultaneously refines the grain size of primary aluminum (α -Al) to ensure that the structural morphology of the primary aluminum is changed from coarse dendrites into equiaxed crystals, thereby improving the hypoeutectic Al-Mg 2 Comprehensive mechanical property of Si alloy. The invention discloses a protected metal Bi and ultrasonic compositeThe treatment is an item which not only achieves the purposes of refining crystal grains, degassing, removing impurities, improving looseness and segregation, but also can effectively improve the quality of the cast ingot, and the method has the advantages of simple operation, low cost, environmental protection and suitability for popularization and application.)

1. Ultrasonic treatment and Bi composite refined hypoeutectic Al-Mg₂The method for forming the Si alloy structure is characterized by comprising the following steps:

(1) weighing the alloy raw materials in percentage by weight as follows:

3.17 to 6.34 percent of magnesium block,

1.83 to 3.66 percent of silicon particles,

the rest is aluminum block for standby;

(2) heating and melting the aluminum blocks and the silicon particles weighed in the step (1), cooling, adding a preheated magnesium block, preserving heat and standing after the magnesium block is completely melted, adding a degassing refining agent for the first time, stirring, and removing scum to obtain a refined alloy melt;

(3) adding modifier Bi particles into the alloy melt obtained in the step (2), standing, and then carrying out secondary refining treatment on the alloy melt to obtain a refined alloy melt;

(4) and (4) carrying out ultrasonic external field treatment on the refined alloy melt obtained in the step (3), and then carrying out casting molding to obtain a casting finished product.

2. The ultrasonically treated and Bi compositely refined hypoeutectic Al-Mg of claim 1₂A method for forming a Si alloy structure, characterized in that a hypoeutectic Al-5% Mg is prepared by melting₂Si alloyThe gold is respectively called as the following alloy raw materials in the step (1): 3.17% of magnesium blocks, 1.83% of silicon particles and the balance of aluminum blocks; if smelting, hypoeutectic Al-10% Mg is prepared₂The Si alloy is respectively called as the following alloy raw materials in the step (1): 6.34 percent of magnesium blocks, 3.66 percent of silicon particles and the balance of aluminum blocks.

3. The ultrasonically treated and Bi compositely refined hypoeutectic Al-Mg of claim 1₂The method for forming a Si alloy structure is characterized in that, in the step (2), the preheating temperature of the magnesium block is 250-300 ℃, and the input temperature of the magnesium block is not higher than 750 ℃.

4. The method of claim 3, wherein the ultrasonic treatment and Bi composite refining hypoeutectic Al-Mg₂The method for forming the Si alloy structure is characterized in that the melting and heat preservation temperature of the magnesium block is 720-740 ℃, and the heat preservation and standing time is 10-15 min.

5. The method of claim 4, wherein the ultrasonic treatment and Bi composite refining hypoeutectic Al-Mg₂The method for forming the Si alloy structure is characterized in that the temperature of a melt system is 730-750 ℃ when the degassing refining agent is added, the addition amount of the degassing refining agent is 0.3-0.5 wt% of the total mass of the melt, and the refining stirring time is 1-1.5 min.

6. The ultrasonically treated and Bi compositely refined hypoeutectic Al-Mg of claim 1₂The method for forming the Si alloy structure is characterized in that in the step (3), the addition amount of the modifier Bi particles is 0.05-0.3 wt% of the total mass of the melt, and the standing time for adding the modifier Bi particles is 1-3 min.

7. The ultrasonically treated and Bi compositely refined hypoeutectic Al-Mg of claim 1₂The method for forming the Si alloy structure is characterized in that the ultrasonic treatment process in the step (4) is as follows: immersing the preheated ultrasonic amplitude transformer into the refined melt, and carrying out ultrasonic heat preservation on the refined meltThe temperature is 615-650 ℃, the processing time is 60-180 s, and the ultrasonic power is 800-1800W.

8. The method of claim 7, wherein the ultrasonic treatment and the Bi composite refining hypoeutectic Al-Mg₂The method for forming the Si alloy structure is characterized in that the preheating temperature of the ultrasonic amplitude transformer is 300-350 ℃.

9. The ultrasonically treated and Bi compositely refined hypoeutectic Al-Mg of claim 1₂The method for forming the Si alloy structure is characterized in that the casting molding process comprises the following steps: and casting the alloy liquid after ultrasonic treatment into a metal mold preheated to 250-300 ℃ for molding to obtain a corresponding casting.

Technical Field

The invention relates to a magnesium alloy smelting and casting technology, in particular to a hypo (near) eutectic Al-Mg-Si series alloy containing Mg₂A casting structure refining technology of Si strengthening phase, and particularly discloses an ultrasonic treatment and Bi composite refining hypoeutectic Al-Mg₂A method of forming a Si alloy structure.

Background

Due to casting Al-Mg₂The Si alloy has the excellent performances of low density, good thermal conductivity, low thermal expansion coefficient, high specific strength, good wear resistance and corrosion resistance, and is widely concerned by people, so the alloy becomes a potential material applied in the industrial fields of aerospace, automobiles and the like. But due to hypo (near) eutectic Al-Mg₂The as-cast structure of Si alloy is generally composed of coarse dendritic primary aluminum (α -Al) and coarse eutectic Mg in the form of needle, rod or Chinese character₂Si phase, coarse needle-like, rod-like or Chinese character-like eutectic Mg₂Si seriously cracks Al matrix, generates stress concentration, forms crack source and seriously reduces hypoeutectic Al-Mg₂Tensile strength of Si alloy. In addition, the alloy contains other defects such as air holes, component segregation and the like, and the comprehensive mechanical property of the alloy is influenced, so that the application of the alloy in actual production is limited.

For the hypoeutectic Al-Mg₂The defects of Si alloy structure are mainly researched by adopting alkali metal and rare earth to sub (near) eutectic Al-Mg₂Mg in Si alloy₂The Si phase is modified, but part of modifier has poor modification effect and relatively high cost.

Therefore, the development of a method for refining an alloy structure with low cost and high efficiency becomes a problem which needs to be solved by the technical personnel in the field.

Disclosure of Invention

In view of the above, the present invention provides a hypoeutectic Al-Mg with ultrasonic treatment and Bi composite refining for solving the problems in the prior art₂Method for refining dendritic primary aluminium (α -Al) and eutectic Mg by ultrasonic treatment in hypoeutectic Al-Mg-Si alloy and addition of metal Bi₂Si phase to strengthenComprehensive mechanical properties of the alloy.

In particular, due to the as-cast hypoeutectic Al-Mg₂Coarse primary aluminum (α -Al) dendrites and plate-like and needle-like eutectic Mg are generally present in the microstructure of Si alloys₂Si phase, which adversely affects the mechanical properties of the alloy, particularly tensile properties and ductility, and therefore controls primary α -Al and eutectic Mg₂The shape and size of the Si crystal are improved to hypoeutectic Al-Mg₂The Al-Ti-B and Al-Ti-C system intermediate alloy is often added in the current aluminum alloy industrial production to refine the coarse α -Al dendrite in the matrix, and various trace elements or compounds are added in the prior art, such as Gd, Na, Ba, Sr, L a, Bi, Nd, K, etc₂TiF₆Etc. to hypoeutectic Al-Mg₂Eutectic Mg of Si alloy₂The Si phase is modified. But because gas is easily generated in the alloy modification process, the defects of shrinkage cavity and shrinkage porosity are generated. Meanwhile, the modified elements react with the eutectic phase to generate new intermetallic compounds, which are not uniform in the matrix and cause segregation, so that the development of a method for refining hypoeutectic Al-Mg, which can solve the technical problems in the prior art, is urgently needed₂A method of forming a Si alloy structure.

In order to achieve the purpose, the invention adopts the following technical scheme:

ultrasonic treatment and Bi composite refined hypoeutectic Al-Mg₂A method of Si alloy structure, the method comprising the steps of:

(1) weighing the alloy raw materials in percentage by weight as follows:

3.17 to 6.34 percent of magnesium block,

1.83 to 3.66 percent of silicon particles,

the rest is aluminum block for standby;

(2) heating and melting the aluminum blocks and the silicon particles weighed in the step (1), cooling, adding a preheated magnesium block, preserving heat and standing after the magnesium block is completely melted, adding a degassing refining agent for the first time, stirring, and removing scum to obtain a refined alloy melt;

(3) adding modifier Bi particles into the alloy melt obtained in the step (2), standing, and then carrying out secondary refining treatment on the alloy melt to obtain a refined alloy melt;

(4) and (4) carrying out ultrasonic external field treatment on the refined alloy melt obtained in the step (3), and then carrying out casting molding to obtain a casting finished product.

Further preferably, hypoeutectic Al-5% Mg is prepared if smelting₂The Si alloy is respectively called as the following alloy raw materials in the step (1): 3.17% of magnesium blocks, 1.83% of silicon particles and the balance of aluminum blocks; if smelting, hypoeutectic Al-10% Mg is prepared₂The Si alloy is respectively called as the following alloy raw materials in the step (1): 6.34 percent of magnesium blocks, 3.66 percent of silicon particles and the balance of aluminum blocks.

The alloy raw materials are industrial pure aluminum (Al is more than or equal to 99.7 percent), pure magnesium (Mg is more than or equal to 99.6 percent), crystalline silicon (Si is more than or equal to 99.5 percent, the particle size is 2-10 mm) and metal bismuth (99.99 percent).

Further, in the step (2), the preheating temperature of the magnesium block is 250-300 ℃, and the input temperature of the magnesium block is not higher than 750 ℃.

Further, the melting and heat preservation temperature of the magnesium block is 720-740 ℃, and the heat preservation and standing time is 10-15 min.

Furthermore, the temperature of the melt system is 730-750 ℃ when the degassing refining agent is added, the addition amount of the degassing refining agent is 0.3-0.5 wt% of the total mass of the melt, and the refining stirring time is 1-1.5 min. Among them, the refining agent is preferably C₂Cl₆。

Further, in the step (3), the addition amount of the modifier Bi particles is 0.05-0.3 wt% of the total mass of the melt, and the standing time for adding the modifier Bi particles is 1-3 min.

Further, the ultrasonic treatment process in the step (4) comprises the following steps: and immersing a preheated ultrasonic amplitude transformer into the refining melt, and carrying out ultrasonic heat preservation on the refining melt at the temperature of 615-650 ℃, the treatment time of 60-180 s and the ultrasonic power of 800-1800W.

Furthermore, the preheating temperature of the ultrasonic amplitude transformer is 300-350 ℃.

Further, the casting molding process comprises the following steps: and casting the alloy liquid after ultrasonic treatment into a metal mold preheated to 250-300 ℃ for molding to obtain a corresponding casting.

In conclusion, the invention provides a method for refining hypoeutectic Al-Mg by adopting ultrasonic external field and modification combined treatment₂A Si alloy structure method is characterized in that optimal experimental results of ultrasonic treatment of different ultrasonic powers of 640-650 ℃, 625-635 ℃, 615-625 ℃, different heat preservation temperature ranges of 60s, 90s, 120s, 150s and 180s, different ultrasonic treatment times of 800W, 1000W, 1200W, 1400W, 1600W and 1800W show that hypoeutectic Al-10Mg is obtained when the optimal ultrasonic treatment process parameters are 620 ℃, ultrasonic treatment time is 150s and ultrasonic power is 1800W₂Primary aluminum (α -Al) in the alloy structure of the Si alloy is completely converted into fine nearly spherical isometric crystal and eutectic Mg from coarse dendrites₂Si is changed into fine coral, fiber and particle from plate-shaped and needle-shaped structures.

Further, when the alloy is compositely refined with the metal-containing Bi in an amount of 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3% respectively under the above optimum ultrasonic external field treatment process parameters, it was found through experiments that when the alloy is compositely refined and modified with Bi by ultrasonic treatment, the optimum Bi content is 0.15% to 0.25%, and the eutectic Mg in the alloy is eutectic₂Si becomes fine coral-like or granular.

In particular to hypoeutectic Al-Mg with ultrasonic treatment and Bi composite refining₂The method for Si alloy structure adopts the combined treatment mechanism of ultrasonic external field and modification as follows:

when the ultrasonic external field treatment is transmitted in the metal melt, a series of physical phenomena such as ultrasonic cavitation, acoustic current, overheating, resonance and the like can be generated, and the hypo (near) eutectic Al-Mg is subjected to ultrasonic cavitation nucleation proliferation and fragmentation₂The formed α -Al dendrite in the Si alloy melt is refined to change the primary α -Al into equiaxed crystal, and simultaneously, the gas in the alloy can be removed, and the loose segregation can be improved.

In addition, Bi element is adopted to eutectic Mg₂Si phase is modified to become spherical or fibrous and granular structureThe cracking function of the strengthening relative to the alloy matrix is reduced, so that the comprehensive mechanical property of the as-cast alloy structure is improved.

Meanwhile, the addition of metal Bi can improve the cutting performance of the alloy and prevent the alloy from being oxidized. The composite treatment of metal Bi and ultrasonic not only achieves the purposes of refining crystal grains, degassing, removing impurities, improving looseness and segregation and improving the quality of cast ingots, but also has the advantages of simple operation, low cost and environmental protection, so the composite application of the ultrasonic treatment and Bi to the refining of hypoeutectic Al-Mg₂The Si alloy structure is a technology with wide application prospect and engineering research value.

It should be noted that, hitherto, hypoeutectic Al-Mg₂Relatively few reports of Si alloy research are reported, wherein Bi is researched for Al-10% Mg by Wu et Al, Liaoning Industrial university₂The influence of the texture and mechanical properties of the Si alloy is found out that the addition of Bi to the as-cast Al-10Mg₂Eutectic Mg in Si alloys₂Si has obvious modification and refinement effects. Eutectic Mg in as-cast alloys₂The morphology of Si is changed from a plate-like structure to a thin coral-like and fibrous structure, the tensile strength of the as-cast alloy which is not deteriorated is 213MPa, and when the Bi content is 0.60 wt%, the ultimate tensile strength of the alloy reaches 270 MPa.

In addition, Tianjin university L i et Al para hypoeutectic Al-10% Mg₂The Si alloy is subjected to solution treatment at 520 ℃ for × 6h and aging treatment at 200 ℃ for × 6h, and eutectic Mg in the alloy after heat treatment is found₂The Si phase grows into a rod shape and is converted into short fiber shape and a ball shape, and the tensile strength is improved from 186MPa which is not treated to 234.6 MPa.

Therefore, in summary, compared with the prior art, the hypoeutectic Al-Mg compound refined by ultrasonic treatment and Bi disclosed by the invention₂The method for forming the Si alloy structure has the advantages that:

the invention refines hypoeutectic Al-Mg by adopting metal Bi as a modifier₂Eutectic Mg in Si alloys₂Si reinforcement, changing the plate-shaped and needle-shaped structure into coral-shaped, fiber-shaped and granular, and eliminating the cast hypoeutectic Al-Mg by ultrasonic treatment₂Gas generated in the modification process of the Si alloy reduces shrinkage cavity, shrinkage porosity and segregation defects of metal BiSimultaneously, the grain size of primary aluminum (α -Al) is refined, the structural morphology of the primary aluminum is changed from coarse dendrites into equiaxed crystals, and finally the hypoeutectic Al-Mg is improved₂Comprehensive mechanical property of Si alloy. The invention discloses a method for carrying out composite treatment on metal Bi and ultrasonic, which not only achieves the purposes of refining crystal grains, degassing, removing impurities, improving looseness and segregation, but also can effectively improve the quality and performance of cast ingots.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts

FIG. 1 shows 500 times lower amount of hypoeutectic Al-10Mg in a metal mold without ultrasonic treatment and deterioration₂And (3) a metallographic microstructure of the Si alloy.

FIG. 2 shows hypoeutectic Al-10Mg with 500 times of metal mold ultrasonic treatment at 640-650 ℃ for 150s and ultrasonic power of 800W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 3 shows hypoeutectic Al-10Mg with 500 times of metal mold ultrasonic treatment at 640-650 ℃ for 150s and ultrasonic power of 1000W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 4 shows hypoeutectic Al-10Mg with 500 times of metal mold ultrasonic treatment at 640-650 ℃ for 150s and ultrasonic power of 1200W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 5 shows hypoeutectic Al-10Mg with 500 times of metal mold ultrasonic treatment at 640-650 ℃ for 150s and ultrasonic power of 1400W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 6 shows hypoeutectic Al-10Mg with 500 times of metal mold ultrasonic treatment at 640-650 ℃ for 150s and ultrasonic power of 1600W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 7 shows hypoeutectic Al-10Mg with 500 times lower metal mold, ultrasonic treatment at 640-650 ℃ for 150s and ultrasonic power of 1800W₂Metallographic phase of Si alloyAnd (4) a microstructure picture.

FIG. 8 shows hypoeutectic Al-10Mg with 500 times lower metal mold subjected to ultrasonic treatment at 625-635 ℃ for 150s and ultrasonic power of 800W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 9 shows hypoeutectic Al-10Mg with 500 times lower metal mold subjected to ultrasonic treatment at 625-635 ℃ for 150s and ultrasonic power of 1000W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 10 shows hypoeutectic Al-10Mg with 500 times lower metal mold subjected to ultrasonic treatment at 625-635 ℃ for 150s and ultrasonic power of 1200W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 11 shows hypoeutectic Al-10Mg with 500 times lower metal mold subjected to ultrasonic treatment at 625-635 ℃ for 150s and ultrasonic power of 1400W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 12 shows 500 times of hypoeutectic Al-10Mg in a metal mold subjected to ultrasonic treatment at 625-635 ℃ for 150s and ultrasonic power of 1600W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 13 shows hypoeutectic Al-10Mg with 500 times lower metal mold subjected to ultrasonic treatment at 625-635 ℃ for 150s and ultrasonic power of 1800W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 14 shows hypoeutectic Al-10Mg with 500 times of metal mold, ultrasonic treatment is carried out at 615-625 ℃ for 150s, and ultrasonic power is 800W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 15 shows hypoeutectic Al-10Mg with 500 times of metal mold, ultrasonic treatment is carried out at 615-625 ℃ for 150s, and ultrasonic power is 1000W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 16 shows hypoeutectic Al-10Mg with 500 times of metal mold, ultrasonic treatment is carried out at 615-625 ℃ for 150s and ultrasonic power is 1200W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 17 shows hypoeutectic Al-10Mg with 500 times of metal mold being subjected to ultrasonic treatment at 615-625 ℃ for 150s and ultrasonic power of 1400W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 18 shows hypoeutectic Al-10Mg with 500 times of metal mold being subjected to ultrasonic treatment at 615-625 ℃ for 150s and ultrasonic power of 1600W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 19 shows hypoeutectic Al-10Mg with 500 times of metal mold being subjected to ultrasonic treatment at 615-625 ℃ for 150s and ultrasonic power of 1800W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 20 shows hypoeutectic Al-10Mg with 500 times of metal mold being subjected to ultrasonic treatment at 615-625 ℃ for 60s and ultrasonic power of 1800W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 21 shows hypoeutectic Al-10Mg with 500 times of metal mold being subjected to ultrasonic treatment at 615-625 ℃ for 90s and ultrasonic power of 1800W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 22 shows hypoeutectic Al-10Mg with 500 times of metal mold being ultrasonically treated at 615-625 ℃ for 120s and ultrasonic power of 1800W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 23 shows hypoeutectic Al-10Mg with 500 times of metal mold being subjected to ultrasonic treatment at 615-625 ℃ for 180s and ultrasonic power of 1800W₂And (3) a metallographic microstructure of the Si alloy.

FIG. 24 shows hypereutectic Al-10Mg modified by 500 times of metal mold at 615-625 deg.C for 150s, ultrasonic power of 1800W and 0.05% Bi₂And (3) a metallographic microstructure of the Si alloy.

FIG. 25 shows hypereutectic Al-10Mg modified by 500 times of metal mold at 615-625 deg.C for 150s, ultrasonic power of 1800W and 0.1% Bi₂And (3) a metallographic microstructure of the Si alloy.

FIG. 26 shows hypereutectic Al-10Mg modified by 500 times of metal mold at 615-625 ℃ for 150s and ultrasonic power of 1800W and 0.15% Bi₂And (3) a metallographic microstructure of the Si alloy.

FIG. 27 shows hypereutectic Al-10Mg modified by 500 times of metal mold at 615-625 ℃ for 150s and ultrasonic power of 1800W and 0.2% Bi₂And (3) a metallographic microstructure of the Si alloy.

FIG. 28 shows hypereutectic Al-10Mg modified by 500 times of metal mold at 615-625 deg.C for 150s, ultrasonic power of 1800W and 0.25% Bi₂And (3) a metallographic microstructure of the Si alloy.

FIG. 29 shows hypereutectic Al-10Mg modified by 500 times of metal mold at 615-625 ℃ for 150s and ultrasonic power of 1800W and 0.3% Bi₂And (3) a metallographic microstructure of the Si alloy.

Detailed Description

The technical solutions disclosed in the present invention will be described clearly and completely with reference to the accompanying drawings, and obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The present invention will be further specifically illustrated by the following examples for better understanding, but the present invention is not to be construed as being limited thereto, and certain insubstantial modifications and adaptations of the invention by those skilled in the art based on the foregoing disclosure are intended to be included within the scope of the invention.

Method for ultrasonic treatment and Bi composite treatment, experimental process and steps for hypoeutectic Al- (5-10%) Mg₂Nascent α -Al and eutectic Mg in Si alloy₂The structure refinement of Si is applicable, so the invention mainly uses to smelt hypoeutectic Al-10Mg₂Si alloy is taken as an example, and hypoeutectic Al-10Mg finally obtained by adopting the technical scheme disclosed by the invention and changing important factor variables is described in the following examples₂The Si alloy casting comprises an ultrasonic treatment power range, an ultrasonic treatment time range, an ultrasonic treatment temperature range, an added modifier adding amount range and the like.