Method for controlling solidification structure of gas phase synergistic double melt blending of ferro-aluminum-silicon alloy

Abstract

The application discloses a method for regulating solidification structure of aluminum-silicon-iron alloy by gas-phase synergistic double-melt blending. CH4 gas is introduced into high-temperature aluminum-titanium alloy liquid, C-containing active particles are decomposed from the CH4 gas in the alloy melt and gas-liquid reaction occurs between the C-containing active particles and Al and Ti particles to generate intermediate phases such as Al4C3 and Ti3AlC and unstable TiC particles, and the intermediate phases react to generate thermodynamically stable TiC nanoparticles. Meanwhile, aluminum-silicon alloy melt and aluminum-iron alloy melt with significant difference in volume and temperature are blended in a controlled diffusion manner to obtain aluminum-silicon-iron melt. During the gas-liquid blending process, due to the opposite directions of solid / liquid interface advancing direction and solute diffusion direction during melt solidification, there exist non-local micro temperature and concentration fluctuations, and grain refinement is realized by controlling the solidification nucleation and diffusion growth process. The gas-liquid casting technology is a new process with multiple processes in synergistic action, and multiple processes can have a superposition effect under synergistic action, so that the synergistic refinement of aluminum-silicon-iron alloy second phase and aluminum grains is realized.

Description

TECHNICAL FIELD

[0001] The application relates to the field of gas-phase synergistic double-melt blending, in particular to a method for regulating the solidification structure of aluminum-silicon-iron alloy by gas-phase synergistic double-melt blending. BACKGROUND

[0002] With the rapid development of photovoltaic power generation, 5G base stations, new energy vehicles and other new material fields, the consumption of aluminum materials in China is increasing day by day. The electrolysis of primary aluminum consumes a lot of energy and pollutes the environment. Therefore, the recycling of waste aluminum has become an inevitable trend for realizing the green and high-quality development of the aluminum industry. The most widely used Al-Si alloy contains iron elements that are difficult to remove, which can significantly deteriorate its structure and performance, and this has become a key obstacle to the large-scale application of recycled aluminum. Previous studies have shown that the introduction of trace elements can modify the coarse phase of recycled aluminum, but the effect is limited. Excessive addition will also lead to the poisoning of other phases and the coarsening of grains, and the performance improvement is limited. There are also related studies that use filtering, ultrasonic, electromagnetic pulse and other methods for treatment, which have made good progress. However, these methods are complex and costly, which is not conducive to mass production. Therefore, the development of low-cost recycled aluminum melt treatment technology, especially the physical refinement and regulation technology for the solidification structure, is the focus and difficulty of the current research in this field.

[0003] The coarse and unevenly distributed primary silicon and iron-rich phase in high-iron aluminum-silicon-iron alloy exhibit sharp and angular and seriously cut the matrix, resulting in the decrease of the mechanical properties of the alloy. Refining the solidification structure (grains and alloy phases) is an effective means to improve the performance of metal cast products, and the most common process is to refine the metal melt. The principle is to form a large number of artificially manufactured non-spontaneous crystal nuclei in the metal liquid by adding or generating in-situ heterogeneous particles similar to the matrix grain structure, thereby increasing the number of effective crystal nuclei to achieve the purpose of refining the structure. The thermal properties and structural stability of heterogeneous particles are important factors to determine whether they can efficiently nucleate. The existence of coarse phases in eutectic Al-Si-Fe alloy makes the refining modification effect of endogenous particles more unstable, and the stability of the modification agent and the nucleation structure is higher. The thermodynamically stable nanoscale TiC particles generated by gas-liquid reaction have the advantages of extremely fast speed, simple preparation process, low material cost, excellent and controllable performance of the prepared material, and can effectively achieve the effect of refining α-Al and the second phase. In addition, by mixing high-temperature Al-Fe melt with low-temperature Al-Si melt at a certain ratio, the solid / liquid interface advancing direction is opposite to the solute diffusion direction to achieve equilibrium state, and an Al-Si-Fe melt with sufficient diffusion and complete reaction is obtained. The small mass and low temperature Al-Ti melt containing liquid TiC nanoparticles after gas-liquid reaction is mixed with the large mass and high temperature eutectic Al-Si-Fe melt to obtain an Al-Si-Fe alloy with uniform structure and grain refinement. In this process, the Al-Ti melt and the Al-Si-Fe melt have a large temperature difference (50-80℃), and the mass ratio of the high-temperature melt is larger. After mixing, the temperature of the high-temperature melt decreases and the temperature of the low-temperature melt increases, and gradually reaches temperature equilibrium. During this period, mass transfer is accompanied by lateral diffusion of liquid and mixture, resulting in a liquid with uniform chemical composition in the entire mixture. Compared with heat transfer, inverse diffusion is easy to form non-local energy composition fluctuations. Under the action of chilling of the low-temperature melt, high-temperature low-concentration solute microzones nucleate under a large degree of supercooling and grow towards the low-temperature high-concentration zone. Under the control of inverse diffusion mode, the composition supercooling effect is small, and the α-Al grains tend to grow equiaxially, and the growth of coarse acicular iron-rich phase is inhibited, thereby achieving the purpose of refining the alloy structure. Compared with the traditional casting process, the present patent has the advantages of short process of mixed melt, no need for isothermal maintenance, shorter solidification time, no residual liquid, uniform alloy structure, grain refinement, etc.

[0004] The Al-Si-Fe alloy organization is improved by using traditional casting method, using calcium, sodium, strontium modification elements, but the modification by the method of adding elements will make the aluminum alloy composition more complex, and because the material often contains a certain amount of impurity elements, the ordinary grain refiner is easy to produce refinement "poisoning" effect, which is not conducive to standardized production. The patent numbers CN209798050U, CN114293021A, etc. all adopt alloy filtration purification method to remove micro impurities in the melt to improve the purity of aluminum liquid. But these methods are complex in operation, high in cost and long in production process, which is not conducive to batch production. The patent first uses high-temperature Al-Fe melt and low-temperature Al-Si melt to obtain Al-Si-Fe melt, and then introduces the Al-Ti melt containing nano TiC particles generated by gas-liquid reaction into the eutectic Al-Si-Fe alloy melt in a controlled diffusion solidification mode, so as to improve the strength and toughness of the alloy by adjusting the solidification organization. In this process, no new phase is generated, the method is simple and easy to realize industrialized batch production. Therefore, the problem is solved by setting the gas phase and the double melt blending aluminum silicon iron alloy solidification organization regulation method. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a gas phase and double melt blending aluminum silicon iron alloy solidification organization regulation method. The gas phase process quickly generates Al-Ti melt containing TiC particles with the characteristics of thermodynamic stability and low price. The high-temperature Al-Fe melt and the low-temperature Al-Si melt are first blended, which provides the best state for the controlled reverse diffusion of TiC particles in the Al-Si-Fe melt. The Al-Si-Fe alloy melt is blended again with the TiC nano-particle-containing Al-Ti melt generated by the gas phase process, which has a significant refinement effect on the alloy organization. The gas-liquid reaction and controlled diffusion solidification are used to regulate the α-Al grain and the second phase organization, so as to improve the strength and toughness of the cast aluminum alloy at the same time.

[0006] To solve the above technical problems, according to one aspect of the present application, the present application provides the following technical scheme:

[0007] The gas phase and double melt blending aluminum silicon iron alloy solidification organization regulation method comprises:

[0008] S1: melt Al-Ti alloy into a molten state at 1100-1200℃ and place it in a second device, pass a certain amount of methane (CH4) into the molten Al-Ti alloy melt, fully mechanically stir it to make it completely react, obtain Al-Ti alloy melt containing liquid TiC particles and control it to 700-720℃ for standby;

[0009] S2: the Al-Si alloy melt with temperature difference and the Al-Fe alloy melt are mixed in a first device according to a certain mass ratio, fully mechanically stirred and allowed to fully react, the melt temperature is controlled at 750-800 DEG C, and an Al-Si-Fe alloy melt is obtained;

[0010] S3: the prepared Al-Si-Fe alloy melt and the Al-Ti alloy melt containing liquid TiC particles are mixed in a third device, fully mechanically stirred and allowed to fully react, the melt temperature is controlled at 720-740 DEG C, a high-toughness reinforced Al-Si-Fe alloy melt is obtained, and finally the diffusion completed aluminum melt is poured into a pouring mold through an adjusting valve to complete solidification.

[0011] As a preferred scheme of the aluminum silicon iron alloy solidification structure regulation method of the gas phase synergistic double-melt blending, the first device specifically comprises a pouring mold, a runner opened in the pouring mold, a heat preservation layer arranged outside the pouring mold, a temperature regulation layer arranged inside the pouring mold, and a thermocouple installed inside the pouring mold.

[0012] As a preferred scheme of the aluminum silicon iron alloy solidification structure regulation method of the gas phase synergistic double-melt blending, the first device further comprises a rotary motor stirrer installed at the bottom surface of the pouring mold, a pouring opening arranged at the bottom surface of the pouring mold, an adjusting valve installed at the pouring opening, and a runner opening opened at the top surface of the pouring mold.

[0013] As a preferred scheme of the aluminum silicon iron alloy solidification structure regulation method of the gas phase synergistic double-melt blending, the rotary motor stirrer is connected with a stirring rod, and the stirring rod is located in the pouring mold.

[0014] As a preferred scheme of the aluminum silicon iron alloy solidification structure regulation method of the gas phase synergistic double-melt blending, the second device comprises an outer frame, a gas outlet pipeline in communication with the outer frame, a gas inlet pipeline in communication with the outer frame, a gas adjusting valve installed at the gas inlet pipeline, and a bubble generator installed inside the outer frame.

[0015] As a preferred scheme of the aluminum silicon iron alloy solidification structure regulation method of the gas phase synergistic double-melt blending, the third device has the same structure as the first device.

[0016] As a preferred scheme of the aluminum silicon iron alloy solidification structure regulation method of the gas phase synergistic double-melt blending, the materials comprise an Al-Fe alloy melt, an Al-Si alloy melt, an Al-Si-Fe alloy melt, and an Al-Ti alloy melt.

[0017] As a preferred scheme of the gas-phase synergistic double-melt blending method for regulating the solidification structure of Al-Si-Fe alloy, the mixing mass ratio of the Al-Si alloy melt and the Al-Fe alloy melt is controlled to be 1-5, and the mixing mass ratio of the Al-Si-Fe alloy melt and the Al-Ti alloy melt containing liquid TiC particles is controlled to be 2-4.

[0018] As a preferred scheme of the gas-phase synergistic double-melt blending method for regulating the solidification structure of Al-Si-Fe alloy, CH4 is introduced into the high-temperature Al-Ti alloy melt, and TiC particles generated are fully dispersed in the melt by mechanical stirring.

[0019] As a preferred scheme of the gas-phase synergistic double-melt blending method for regulating the solidification structure of Al-Si-Fe alloy, a temperature difference of 30-100℃ exists before the Al-Si alloy melt is mixed with the Al-Fe alloy melt, and a temperature difference of 30-100℃ exists before the Al-Si-Fe alloy melt is mixed with the Al-Ti alloy melt containing liquid TiC particles, and the stirring speed in the S1, S2 and S3 steps is 400-700 rpm.

[0020] Compared with the prior art, the method has the following advantages:

[0021] I. Under the traditional solidification conditions, the concentration fluctuation and temperature fluctuation in the melt are not significant, the number of nucleation is small, and as the temperature continuously decreases, the initial nucleation particles have sufficient time to grow. The β-AlSiFe phase in the Al-Si-Fe alloy is a monoclinic system, which is easy to present a smooth interface lateral growth and exhibit typical anisotropic growth characteristics, and is extremely easy to grow into a coarse needle. For the melt blending process, the Al-Si-Fe eutectic alloy melt is chilled by the Al-Ti alloy melt at the initial stage of mixing, a significant composition and temperature fluctuation zone is formed, the contact area is blended to form an excessive rapid cooling zone, a large supercooling degree is generated to make the primary phase nucleate, and as the mixing gradually becomes uniform and the temperature gradually decreases, the number of primary phase nucleation continues to increase, and a large number of primary nucleation is generated. The large number of primary phase nucleation promotes the refinement, and further affects the solidification process. After the Al-Ti melt containing nano-sized TiC particles is added, TiC reacts with the β-AlSiFe phase and the primary Si phase to generate a second phase which is even smaller, but the nucleation ability of iron and silicon is still strong at the late stage of melt solidification, the small second phase will continue to precipitate between the iron phase and the silicon phase, and the remaining melt will become a single-phase alloy, which can effectively control the formation of eutectic silicon and refine the α-Al grains. Therefore, under the synergistic action of the gas-phase synergistic double-melt blending process, the second phase and the α-Al grains are both refined, so that the strength and toughness of the eutectic Al-Si-Fe alloy are improved.

[0022] Secondly, the production preparation method is simple, the TiC particles are easy to prepare, the composition of the Al-Si-Fe alloy is easy to control, and industrial mass production is easy to realize.

[0023] Thirdly, from the TiC particle preparation to the Al-Si-Fe organization grain refinement process, no pollutants are discharged, and the technology belongs to an environmental protection type. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the present application will be described in detail below in combination with the drawings and detailed embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor. Among them:

[0025] Figure 1 The structural diagrams of the first device, the second device and the third device of the present application;

[0026] Figure 2 The XRD pattern of the traditional smelted Al-7Si-2Fe alloy;

[0027] Figure 3 The XRD pattern of the blended Al-7Si-2Fe alloy;

[0028] Figure 4 The XRD pattern of the traditional smelted Al-12Si-1.7Fe alloy;

[0029] Figure 5 The XRD pattern of the Al-12Si-1.7Fe alloy blended with the Al-Ti melt added with TiC nano-level particles;

[0030] Figure 6 The metallographic structure diagram (100x) of the traditional smelted Al-7Si-2Fe alloy;

[0031] Figure 7 The metallographic structure diagram (100x) of the Al-7Si-2Fe alloy blended with the Al-Fe melt and the Al-Si melt;

[0032] Figure 8 The metallographic structure diagram (100x) of the blended Al-7Si-2Fe alloy with a blending time of 30S;

[0033] Figure 9 The metallographic structure diagram (100x) of the traditional Al-12Si-1.7Fe alloy;

[0034] Figure 10Microstructure of Al-12Si-1.7Fe alloy blended with Al-Fe melt and Al-Si melt (100x);

[0035] Figure 11 Microstructure of Al-12Si-1.7Fe alloy blended with Al-Fe melt and Al-Si melt, and then blended with Al-Ti melt containing TiC nano-particles (100x).

[0036] In the figure: 1, first device; 110, pouring mold; 120, sprue; 130, insulation layer; 140, temperature control layer; 150, thermocouple; 160, rotary motor stirrer; 170, pouring gate; 180, regulating valve; 190, sprue gate; 2, second device; 210, outer frame; 220, gas outlet pipeline; 230, gas inlet pipeline; 240, gas regulating valve; 250, bubble generator; 3, third device; 4, material; 410, Al-Fe alloy melt; 420, Al-Si alloy melt; 430, Al-Si-Fe alloy melt; 440, Al-Ti alloy melt. DETAILED DESCRIPTION

[0037] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0038] In the following description, a lot of specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0039] Secondly, the present application is described in detail in combination with the schematic diagram, and in the detailed description of the embodiments of the present application, the cross-sectional view of the device structure will be partially enlarged without the general proportion for the convenience of description, and the schematic diagram is only an example, which should not limit the scope of protection of the present application. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in the actual manufacture.

[0040] In order to make the objectives, technical solutions and advantages of the present application more apparent, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0041] The Al-Ti melt containing TiC particles with the characteristics of thermodynamic stability and low price is quickly generated by the gas-phase synergistic process. The high-temperature Al-Fe melt and the low-temperature Al-Si melt are first blended, so that the TiC particles in the Al-Si-Fe melt are provided with the best state for controlled reverse diffusion. The TiC nano-particles generated by the gas-phase synergistic process are blended with the Al-Si-Fe alloy melt again, so that the alloy organization is significantly refined. The α-Al grains and the second phase organization are synergistically regulated by using the gas-liquid reaction and controlled diffusion solidification, so that the strength and toughness of the cast aluminum alloy are simultaneously improved.

[0042] Example 1

[0043] The Al-7Si-2Fe alloy is obtained by blending the Al-Fe melt and the Al-Si melt, and the specific metallographic structure is as shown in Figure 7 ;

[0044] The specific steps are as follows: the Al-20Si alloy melt at 600 DEG C is mixed with the Al-10Fe alloy melt at 870 DEG C according to the mass ratio of 3:1, the rotating motor stirrer 160 drives the stirring rod to fully mechanically stir and wait for the complete reaction, the melt temperature is controlled at 750 DEG C, and then the casting is performed to complete the solidification.

[0045] Figure 7 The metallographic structure of the Al-7Si-2Fe alloy obtained by blending is shown in the figure. As shown in the figure, the coarse long needle-shaped iron phase is changed into a small iron phase or a petal shape, mainly distributed around the primary α-Al grains, and the refinement effect is quite obvious; and the primary α-Al grains are obviously refined and become spherical.

[0046] Example 2

[0047] The Al-12Si-1.7Fe melt is obtained by first blending the Al-Fe melt and the Al-Si melt, and then the Al-Ti melt containing TiC nano-particles generated by gas-liquid reaction is blended to obtain the Al-12Si-1.7Fe melt with high strength and toughness, and the specific metallographic structure is as shown in Figure 11 ;

[0048] The specific steps are as follows: first, melt the Al-Ti alloy at 1100-1200℃ into a molten state and place it in the second device 2, then pass the methane gas (CH4) through the gas regulating valve 240 with an inner diameter of 5mm into the second device 2 for 13-16 seconds, control the gas input amount through the gas regulating valve 240, so that the input methane gas and the molten Al-Ti alloy melt 440 reach a volume ratio of 1:6, and fully mechanically stir to make the methane gas and the Al-Ti alloy melt 440 fully react, the stirring is carried out by rotating the stirring rod at high speed driven by the rotating motor, to obtain the Al-Ti alloy melt 440 containing liquid TiC particles and regulate to 700-720℃ for standby, wherein the bubble generator increases the contact area of the contact material;

[0049] Secondly, mix the Al-20Si alloy melt at 600℃ with the Al-10Fe alloy melt at 870℃ in the first device 1 according to a mass ratio of 3:1, during mixing, the rotating motor stirrer 160 drives the stirring rod to fully mechanically stir and wait for complete reaction, control the melt temperature at 750℃, during temperature control, control through the thermocouple 150, and the heat preservation layer 130 reduces the temperature loss speed;

[0050] Finally, mix the prepared Al-Si-Fe alloy melt 430 with the Al-Ti alloy melt 440 containing liquid TiC particles in the third device 3, fully mechanically stir and wait for complete reaction, control the melt temperature at 720-740℃, obtain the high-toughness reinforced Al-Si-Fe alloy melt 430, finally control the temperature to 660℃, pour the diffusion completed aluminum melt into another casting mold through the regulating valve, and complete solidification.

[0051] Figure 9 、 Figure 10 By comparison, the blending is relative to the traditional smelting, as can be seen from the figure, a large number of needle-shaped iron phases are obviously reduced and more uniformly distributed, the eutectic phase is obviously increased, and the primary α-Al is also refined to a certain extent. Figure 11 is the metallographic photograph of the eutectic Al-12Si-1.7Fe alloy modified by adding TiC nano particles, compared with Figure 9 and Figure 10 , the iron phase is obviously reduced, and part of it is transformed into fine needle-shaped or petal-shaped, but the primary α-Al grains are larger, become round and regular, most of them are equiaxed, the structure becomes tight and uniform in size, indicating that the addition of TiC nano particles has more obvious modification effect on the iron phase organization refinement and more sufficient uniform dispersion.

[0052] Comparative Example 1:

[0053] Preparation of traditional Al-7Si-2Fe cast alloy;

[0054] The present comparative example is to illustrate the effect of the gas phase synergistic double melt blending technology, and an Al-7Si-2Fe alloy is prepared by a traditional casting method.

[0055] The implementation is as follows: an Al-20Si alloy and an Al-10Fe alloy are placed into a corundum crucible, a covering agent is added when the temperature is preheated to 350-400°C, a refining agent and a covering agent are added after the temperature is increased to 720°C, and the alloy is cast into a shape at 660°C. The XRD spectrum is shown in Figure 2 The metallographic structure is shown in Figure 6 .

[0056] Figure 6 The metallographic structure of the Al-7Si-2Fe alloy prepared by the traditional melting is shown in the figure, and it can be seen from the figure that the iron phase is mainly distributed in the alloy in the form of long and thick needles, and the distribution is uneven and the size is large.

[0057] Comparative example 2:

[0058] After the high-temperature Al-Fe melt is blended with the low-temperature Al-Si melt, an Al-7Si-2Fe alloy is obtained.

[0059] The implementation is as follows: pure Al and an Al-10Fe alloy are respectively placed into a corundum crucible, a covering agent is added when the temperature is preheated to 350-400°C, a refining agent and a covering agent are added after the temperature is increased to 720°C and 870°C respectively, Al-20Si alloy and pure Al are respectively added when the alloy is in a molten state, the temperature of Al-xSi and Al-yFe is set to 600 and 870°C respectively after the alloy in the two resistance furnaces is in a molten state, a refining agent and a covering agent are added after the temperature reaches the set temperature, the melts in the two corundum crucibles are blended to obtain an Al-Si-Fe melt, and finally pouring is performed. The XRD spectrum is shown in Figure 3 The metallographic structure is shown in Figure 7 .

[0060] Figure 6 The metallographic structure of the Al-7Si-2Fe alloy prepared by the blending melting is shown in the figure, and it can be seen from the figure that the iron phase is refined into fine needles or petal shapes, mainly distributed around the primary α-Al grains, and the refinement effect is quite obvious; and the primary α-Al grains are obviously refined into a spherical shape.

[0061] Comparative example 3:

[0062] After the high-temperature Al-Fe melt is blended with the low-temperature Al-Si melt and is kept for 30S, an Al-7Si-2Fe alloy is obtained.

[0063] The implementation is as follows: using a pit type resistance furnace, pure Al and Al-10Fe alloy are respectively put into corundum crucible, and a covering agent is added when preheating to 350-400 ℃, and when the temperature is respectively increased to 720 ℃ and 870 ℃, the alloy is in a molten state, and Al-20Si alloy and pure Al are respectively added, and after the alloys in the two pit type resistance furnaces are in a molten state, Al-xSi and Al-yFe are respectively set to 600 and 870 ℃, and after the temperature reaches the set temperature, a refining agent and a covering agent are added to remove slag, and then the melts in the two corundum crucibles are blended to obtain an Al-Si-Fe melt, the obtained blended melt is kept for 30 seconds, and finally pouring is carried out. The metallographic structure is as shown in Figure 8

[0064] Figure 8 The metallographic structure of the Al-7Si-2Fe alloy after blending and keeping for 30 seconds can be seen from the figure, the fine iron phase is grown, and the primary α-Al grains are obviously coarsened and change from spherical to petal-shaped, which indicates that the primary α-Al has enough time to diffuse and grow with the increase of the keeping time.

[0065] Comparative Example 4

[0066] Preparation of a traditional Al-12Si-1.7Fe cast alloy

[0067] This comparative example is to illustrate the effect of the gas phase synergistic double melt blending technology, and an Al-12Si-1.7Fe alloy is prepared by a traditional casting method.

[0068] The implementation is as follows: using a pit type resistance furnace, corundum crucible alloy melting, Al-20Si alloy and Al-10Fe alloy are put into corundum crucible, a covering agent is added when preheating to 350-400 ℃, and when the temperature is increased to 720 ℃, the alloy is in a molten state, a refining agent and a covering agent are added after slagging, and casting is formed at 660 ℃. The XRD pattern is as shown in Figure 4 Figure 9

[0069] Figure 9 The metallographic structure of the traditional Al-12Si-1.7Fe cast alloy can be known from the figure, the iron phase is mainly distributed in the alloy in the form of fine and long needles, and the distribution is uneven. At the same time, the alloy contains gray short needle-shaped primary silicon phase, which is distributed around α-Al. When the alloy is affected by load, the two regions will obviously become crack sources.

[0070] Comparative Example 5

[0071] After the high-temperature Al-Fe melt is blended with the low-temperature Al-Si melt, an Al-12Si-1.7Fe alloy is obtained

[0072] ​​​The specific implementation is as follows: using a pit type resistance furnace, pure Al and Al-10Fe alloy are respectively put into corundum crucible, a covering agent is added when preheating to 350-400℃, when the temperature is respectively increased to 720℃ and 870℃, the alloy is in a molten state, Al-20Si alloy and pure Al are respectively added, after the two pit type resistance furnaces are in a molten state, Al-xSi and Al-yFe are respectively set to 600 and 870℃, after the temperature reaches the set temperature, a refining agent and a covering agent are added and slag is removed, then the melts in the two corundum crucibles are blended to obtain an Al-Si-Fe melt, and finally pouring is carried out. The metallographic structure is shown in Figure 10 .

[0073] Figure 10 The metallographic structure of the Al-12Si-1.7Fe alloy prepared by blending smelting is shown in the figure, it can be seen from the figure that the iron phase is obviously reduced and more uniformly distributed, the eutectic phase is obviously increased, and the primary α-Al is also refined to a certain extent.

[0074] Comparative example 6:

[0075] Al-Fe melt is blended with Al-Si melt, and then blended with TiC nanoscale particles generated by gas-liquid reaction to prepare an Al-12Si-1.7Fe alloy;

[0076] The specific implementation is as follows: using a pit type resistance furnace, Al-20Si alloy and Al-10Fe alloy are put into corundum crucible, a covering agent is added when preheating to 350-400℃, when the temperature is increased to 720℃, the alloy is in a molten state, a refining agent and a covering agent are added and slag is removed to obtain an Al-Si-Fe melt. Al-Ti alloy at 1100-1200℃ is melted into a molten state and placed in a second device 2, then methane gas (CH4) is introduced into the second device 2 through a 5mm inner diameter adjusting valve for 13-16 seconds, so that the introduced methane gas and the molten Al-Ti alloy melt reach a volume ratio of 1:6, and the methane gas and the Al-Ti alloy melt are completely reacted by sufficient mechanical stirring to obtain liquid TiC particle-containing Al-Ti alloy melt 440 and are controlled to 700℃ for standby, the prepared Al-Si-Fe melt at 720℃ is blended with the liquid TiC particle-containing Al-Ti alloy melt at 700℃, and after sufficient stirring, it is controlled to 660℃ for casting. The XRD pattern is shown in Figure 5 , and the metallographic structure is shown in Figure 11 .

[0077] Figure 11The metallographic chart of the Al-12Si-1.7Fe alloy containing TiC nano-particle blending shows that the iron phase is obviously reduced, and part of the iron phase is transformed into fine needle-like or petal-like, but the primary α-Al grains are enlarged, become round and regular, most of which are equiaxed, the structure becomes compact and uniform, which shows that the addition of TiC nano-particle has more obvious modification effect on the iron phase organization refinement and more sufficient uniform dispersion.

[0078] For the addition of TiC nano-particle, when it enters the Al-Si-Fe melt, TiC will react with Al in the Al-Si-Fe melt as follows:

[0079] 4Al+3TiC→Al4C3+3Ti (1)

[0080] 3Al+Ti→Al3Ti (2)

[0081] The melting point of Al4C3 phase ( > 2000℃) is very high, and it has very high stability in the Al-Si-Fe melt, so the newly generated Al4C3 phase in the melt disperses into the Al-Si-Fe melt and acts as the nucleation core of the iron phase, and the existence of a large number of Al4C3 particles will promote the iron phase refinement.

[0082] Although the present application has been described with reference to the embodiments above, various improvements can be made thereto and equivalents can be substituted for elements thereof without departing from the scope of the present application. In particular, features of the disclosed embodiments can be combined together in any manner, provided that there is no structural conflict. The combinations of features are not exhaustively described in the specification only for the purpose of omitting the length and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for controlling the solidification structure of an aluminium-silicon-iron alloy by gas phase synergistic twin melt blending, characterized in that, Comprise: S1: Al-Ti alloy is melted into a molten state at 1100-1200℃ and placed into the second device (2), a certain amount of CH4 is introduced into the molten Al-Ti alloy melt, and it is fully reacted by mechanical stirring to obtain an Al-Ti alloy melt containing liquid TiC particles (440) and is controlled to 700-720℃ for standby, so that the introduced methane gas and the molten Al-Ti alloy melt (440) reach a volume ratio of 1:6; S2: The Al-Si alloy melt (420) and the Al-Fe alloy melt (410) with a temperature difference are mixed in the first device (1) according to a certain mass ratio, fully mechanically stirred and allowed to fully react, and the melt temperature is controlled at 750-800℃ to obtain an Al-Si-Fe alloy melt (430); S3: The prepared Al-Si-Fe alloy melt (430) and the Al-Ti alloy melt containing liquid TiC particles (440) are mixed in the third device (3), fully mechanically stirred and allowed to fully react, and the melt temperature is controlled at 720-740℃ to obtain a high-toughness Al-Si-Fe alloy melt (430), and finally the diffused aluminum melt is poured into a casting mold through an adjusting valve to complete solidification; The mixing mass ratio of the Al-Si alloy melt (420) and the Al-Fe alloy melt (410) is controlled at 1-5, and the mixing mass ratio of the Al-Si-Fe alloy melt (430) and the Al-Ti alloy melt containing liquid TiC particles (440) is controlled at 2-4; Before mixing, the Al-Si alloy melt (420) and the Al-Fe alloy melt (410) have a temperature difference of 30-100℃, and the Al-Si-Fe alloy melt (430) and the Al-Ti alloy melt containing liquid TiC particles (440) have a temperature difference of 30-100℃ before mixing, and the stirring speed in steps S1, S2 and S3 is 400-700 rpm.

2. The method of claim 1, wherein the method is characterized by: The first device (1) specifically comprises a pouring mold (110) provided, a sprue (120) opened in the pouring mold (110), a heat preservation layer (130) provided outside the pouring mold (110), a temperature control layer (140) provided inside the pouring mold (110), and a thermocouple (150) installed inside the pouring mold (110).

3. The method of claim 2, wherein the method is characterized by: The first device (1) further comprises a rotary motor stirrer (160) installed on the bottom surface of the pouring mold (110), a pouring opening (170) provided on the bottom surface of the pouring mold (110), an adjusting valve (180) installed at the pouring opening (170), and a sprue opening (190) opened on the top surface of the pouring mold (110).

4. The method of claim 3, wherein the method is characterized by: The output end of the rotary motor stirrer (160) is connected with a stirring rod, and the stirring rod is located in the pouring mold (110).

5. The method of claim 4, wherein the method is characterized by: The second device (2) comprises an outer frame (210), an air outlet pipeline (220) in communication with the outer frame (210), an air inlet pipeline (230) in communication with the outer frame (210), a gas regulating valve (240) installed at the air inlet pipeline (230), and a bubble generator (250) installed inside the outer frame (210).

6. The method of claim 5, wherein the method is characterized by: The third device (3) is equal in structure to the first device (1).

7. The method of claim 6, wherein the method is characterized by: The material (4) comprises an Al-Fe alloy melt (410), an Al-Si alloy melt (420), an Al-Si-Fe alloy melt (430), and an Al-Ti alloy melt (440).

8. The method of claim 7, wherein the method is characterized by: CH4 is introduced into the high-temperature Al-Ti alloy melt, and TiC particles generated are fully dispersed in the melt by mechanical stirring.

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