Aluminum alloy iron-rich phase regulation and control method based on TiB2 system process optimizer

Abstract

The invention relates to the technical field of aluminum alloy materials, in particular to an aluminum alloy iron-rich phase regulation and control method based on a TiB2 series process optimizer. The method comprises the following steps: adding KBF4 and K2TiF6 into an aluminum melt to regulate and control the contents of B and Ti, and obtaining a required Al-TiB2 regulation and control melt through multi-stage rotary blowing refining; the regulation and control melt is added into an aluminum alloy melt according to the designed mass fraction, then extrusion casting forming is utilized, regulation and control over the form and distribution of an iron-rich phase in a final product are achieved, and therefore the microstructure and the overall performance of the extrusion casting aluminum alloy under the medium-high Fe content are remarkably improved; the problem that the overall material performance is affected due to the fact that the beta-Fe phase is difficult to completely eliminate and the volume fraction of the multi-element iron-rich phase is difficult to improve due to addition of Mn in an existing regulation and control method is solved.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy materials technology, and specifically to a method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers. Background Technology

[0002] Aluminum alloys are widely used in transportation, aerospace, and other fields due to their low density, high specific strength, and excellent corrosion resistance. In the aluminum alloy processing and manufacturing industry, extrusion casting technology, as a forming manufacturing process combining the advantages of forging and casting, is now applied to the production of castings with large wall thickness variations, high performance requirements, and complex structures, showing enormous development potential and application prospects. With the continuous improvement of performance requirements for aluminum alloys and the advancement of energy conservation and emission reduction goals, the utilization of recycled aluminum not only helps conserve natural resources and alleviate environmental pressure but also effectively reduces production costs and improves energy efficiency.

[0003] However, the recycling of aluminum alloys faces challenges due to the diversity and inhomogeneity of the chemical composition of the waste, making it difficult to remove or control the harmful effects of trace elements on casting performance during the smelting stage. Fe is the most common impurity element in recycled aluminum alloys. Because Fe has low solid solubility in aluminum, only 0.05 wt% at room temperature, it usually exists as a second phase. In the extrusion casting process, the size, shape, and distribution of the iron-rich phase are jointly controlled by factors such as alloy composition, pouring temperature, and extrusion pressure, directly affecting the strength, ductility, and machinability of the casting.

[0004] Currently, research on the regulation of the iron-rich second phase mainly focuses on the regulation of trace alloying elements, among which Mn is the most important regulating element. The addition of Mn can inhibit the formation of β-Fe phase and promote the transformation of needle-like β-Fe phase into Chinese character-shaped α-Fe phase, but it is still difficult to completely eliminate β-Fe phase. At the same time, the addition of Mn will also increase the volume fraction of quaternary iron-rich phase in casting. When the Fe content in the melt is high, the addition of a large amount of Mn will significantly increase the volume fraction of multi-element iron-rich phase, thereby affecting the overall material properties. Summary of the Invention

[0005] To address the problem that existing control methods using Mn are insufficient to completely eliminate the β-Fe phase and increase the volume fraction of the multi-component iron-rich phase, thus affecting the overall material properties, the present invention aims to provide a method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] This invention provides a method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers, comprising the following steps: A boron (B) source is added to the aluminum melt, followed by a Ti source at 840℃~860℃. After heat treatment, multi-stage rotary blowing refining is performed to obtain an Al-TiB2 controlled melt. The mass ratio of B to Ti is 1:1.9~2.4. The Al-TiB2 controlled melt is added to the aluminum alloy melt, and after rotary blowing refining, it is extruded and cast to achieve control over the morphology and distribution of the iron-rich phase in the extruded aluminum alloy. The amount of Al-TiB2 controlled melt added accounts for 0.1%~1% of the mass percentage of the aluminum alloy melt.

[0008] This invention provides a method for controlling the iron-rich phase in extruded aluminum alloys. The method involves adding KBF4 and K2TiF6 to the aluminum melt to control the B and Ti content, and then refining it through multi-stage rotary blowing to obtain the desired Al-TiB2 controlled melt. The controlled melt is then added to the aluminum alloy melt according to a designed mass fraction, and extrusion casting is used to achieve control over the morphology and distribution of the iron-rich phase in the final product, thereby significantly improving the microstructure and overall properties of extruded aluminum alloys with medium to high Fe content. While influencing the iron-rich phase, the introduced TiB2 particles can simultaneously exert a refining and modifying effect through uniform nucleation and a strengthening effect through the second phase, resulting in a more superior synergistic control effect on the as-cast microstructure.

[0009] Preferably, in the Al-TiB2 controlled melt, the mass percentage of B element is 1% to 3% and the mass percentage of Ti element is 3% to 5%.

[0010] Preferably, the mass ratio of B to Ti is 1:1.9 to 2.4. For example, 1:1.9, 1:2, and 1:2.4, etc.

[0011] This invention controls the mass ratio of boron (B) to titanium (Ti) during the preparation process to be between 1:1.9 and 2.4. This not only ensures the stability and repeatability of the reaction but also directly affects the size and morphology of the generated TiB2 particles. Specifically, with increasing Ti content, the TiB2 particles gradually grow into larger plate-like shapes, and the particle size is submicron, approximately 0.1 μm to 3 μm. These submicron particles can not only be uniformly dispersed in the aluminum alloy matrix through rotary spraying but also provide a higher surface area, enhancing the refining effect.

[0012] Preferably, the amount of Al-TiB2 controlled melt added accounts for 0.3% to 1% of the mass percentage of the aluminum alloy melt.

[0013] This invention utilizes Al-TiB2 as a melt refiner, added to aluminum alloy melt. The amount of Al-TiB2 added is 0.3% to 1%, with the TiB2 component added at 0.006 wt% to 0.03 wt%. This significantly improves the size and morphology of the iron-rich phase. TiB2 provides effective nucleation sites, promoting grain refinement and the control of the iron-rich phase.

[0014] Elemental regulation methods, such as adding Mn or Cr to control the iron-rich phase, can achieve some degree of control, but these methods have drawbacks such as introducing new intermetallic compounds, potentially reducing the material's plasticity and toughness, increasing production costs, increasing process complexity, and impacting the environment and recycling, and may adversely affect other material properties. This invention, by adding trace amounts of a highly efficient refining agent, is simple and efficient, avoiding the aforementioned problems.

[0015] Preferably, the B source is KBF4; the Ti source is K2TiF6.

[0016] Preferably, after multi-stage rotary jet refining, the process further includes: a settling treatment, followed by cooling to 750°C to 780°C when the conductivity of the Al-TiB2 melt is controlled at 50% IACS to 60% IACS.

[0017] In this invention, when the conductivity of the Al-TiB2 melt is controlled at 50% IACS to 60% IACS, the amount of TiB2 generated in the melt has reached the target value and is uniformly distributed. Cooling at this point helps maintain the stability of the melt. Excessive temperature can cause some TiB2 particles to agglomerate. If the conductivity exceeds the target range, excessive TiB2 generation or uneven particle distribution may lead to grain coarsening or reduced material properties.

[0018] Preferably, the parameters for extrusion casting are: forming pressure of 80MPa to 140MPa and forming speed of 0.04m / s to 1.0m / s.

[0019] Preferably, the aluminum alloy is an aluminum alloy with an iron content of 0.4 wt.% to 0.5 wt.%.

[0020] Preferably, the aluminum alloy is an aluminum-silicon based cast aluminum alloy. For example, aluminum-silicon based cast aluminum alloys such as A356.

[0021] Preferably, the aluminum alloy is AlSi. 10 MgFe 0.5 or AlSi 10 MgMnFe 0.5 .

[0022] Preferably, the temperature for heat preservation is 840℃~860℃; and the heat preservation time is 60min~90min.

[0023] Preferably, the rotary jet refining speed is 200 r / min to 300 r / min, and the jetting time is 1 min to 5 min.

[0024] The beneficial effects of this invention are: 1. This invention primarily controls the size and morphology of submicron-sized TiB2 particles by controlling the Ti / B mass ratio. This allows the submicron-sized particles to be uniformly dispersed in the aluminum alloy matrix through rotary spraying, providing a higher specific surface area and enhancing the refining effect. This invention mainly uses Al-TiB2-controlled melt as a refining agent to simply and efficiently regulate the morphology of iron-rich phases, significantly improving the performance of aluminum alloy materials. It solves the problem in existing methods where the addition of Mn is insufficient to completely eliminate the β-Fe phase and increase the volume fraction of multi-component iron-rich phases, thus affecting the overall material properties.

[0025] 2. The method of the present invention can ensure the stability and repeatability of the reaction by controlling the Ti / B mass ratio; the Al-TiB2 controlled melt method of the present invention can significantly improve the morphology and distribution of iron-rich phase in the as-cast microstructure of aluminum alloys under medium-high Fe content conditions, and reduce the adverse effects of iron-rich phase.

[0026] 3. The method of the present invention can significantly optimize the distribution of Fe element and the morphology of iron-rich phase in aluminum alloys, improve the overall strength and toughness of the material, provide a technical solution for the application of medium and high Fe content aluminum alloys, reduce material costs, and improve green recycling efficiency.

[0027] 4. The method of the present invention does not require complex equipment or processes, is easy to integrate into existing production lines, and requires relatively small amounts, so it will not significantly increase production costs. The overall method is safer and suitable for large-scale industrial production. Attached Figure Description

[0028] Figure 1The figures show the Fe element distribution in the matrix specimen prepared by the method of Comparative Example 1 and the Al-TiB2-added aluminum alloy extrusion casting specimen prepared by the method of Example 1. (a) shows the Fe element distribution in the matrix specimen prepared by the method of Comparative Example 1; (b) shows the Fe element distribution in the Al-TiB2-added aluminum alloy extrusion casting specimen prepared by the method of Example 1. (a1) is a cross-sectional view of the matrix test bar prepared by the method of Comparative Example 1; (a2) is a Fe element distribution diagram of the longitudinal section of the matrix test bar prepared by the method of Comparative Example 1; (a3) ​​is a Fe element signal intensity distribution diagram of the longitudinal section of the matrix test bar prepared by the method of Comparative Example 1; (b1) is a cross-sectional view of the longitudinal section of the aluminum alloy extrusion casting test bar with Al-TiB2 added prepared by the method of Example 1; (b2) is a Fe element distribution diagram of the longitudinal section of the aluminum alloy extrusion casting test bar with Al-TiB2 added prepared by the method of Example 1; (b3) is a Fe element signal intensity distribution diagram of the longitudinal section of the aluminum alloy extrusion casting test bar with Al-TiB2 added prepared by the method of Example 1.

[0029] Figure 2 The microstructure of the iron-rich phase microstructure of the aluminum alloy extrusion casting specimen with Al-TiB2 added, prepared by the method of Example 1, is shown by scanning electron microscopy backscattered electron microscopy.

[0030] Figure 3 The backscattered electron phase of the iron-rich phase microstructure of the matrix specimen prepared by the method of Comparative Example 1 is shown in the scanning electron microscope.

[0031] Figure 4 These are longitudinal cross-sectional views of aluminum alloy extrusion casting test bars with Al-TiB2 added, prepared by different mass ratios of B and Ti elements. Among them, (a) is a longitudinal cross-sectional view of the matrix test bar prepared by the method of Comparative Example 1; (b) is a longitudinal cross-sectional view of the aluminum alloy extrusion casting test bar with Al-TiB2 added prepared by the method of Example 1; and (c) is a longitudinal cross-sectional view of the aluminum alloy extrusion casting test bar with Al-TiB2 added prepared by the method of Example 2. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Recycled aluminum, also known as recycled aluminum, contains iron (Fe), the most common impurity element. Due to its low solid solubility in aluminum (only 0.05 wt% at room temperature), Fe typically exists as a second phase. In the extrusion casting process, the size, shape, and distribution of the iron-rich phase are controlled by factors such as alloy composition, pouring temperature, and extrusion pressure, directly affecting the strength, ductility, and machinability of the casting.

[0035] Currently, the main approach is to add manganese (Mn) as a regulating element to suppress the formation of the β-Fe phase and promote the transformation of the needle-like β-Fe phase into the Chinese character-shaped α-Fe phase. However, it is still difficult to completely eliminate the β-Fe phase. Simultaneously, the addition of Mn will increase the volume fraction of the quaternary iron-rich phase in the casting. When the Fe content in the melt is high, the addition of a large amount of Mn will significantly increase the volume fraction of the multi-element iron-rich phase, thus affecting the overall material properties.

[0036] In addition, although rare earth elements can be adsorbed on the surface of iron-rich phase particles in aluminum melt, hindering the growth of the iron-rich phase in a certain direction and promoting the transformation of the β-Fe phase into a dispersed fine granular α-Fe phase, their high cost limits their widespread application.

[0037] TiB2, as a high-performance ceramic particle reinforcing phase, shows great potential as a grain refiner and second-phase regulator in aluminum alloy matrices. TiB2 not only possesses a high melting point, good thermal stability, and excellent hardness, but also exhibits growth inhibition and heterogeneous nucleation effects. Experimental studies have shown that TiB2 particles can effectively improve the microstructure of castings, shorten and coarsen the iron-rich phase, thereby achieving dispersion control of the iron-rich phase and improving the performance of aluminum alloys at a relatively low cost.

[0038] To address the shortcomings of existing technologies, this invention proposes a method for controlling the iron-rich phase in extrusion-cast aluminum alloys. Ti and B elements are mixed in a specific ratio to create a stable Al-TiB2 controlled alloy melt. Before the refining and degassing process of the aluminum alloy melt, an appropriate amount of Al-TiB2 controlled melt is added. This, combined with the extrusion casting process, improves the alloy microstructure, particularly the dispersion control of the iron-rich phase, thereby enhancing the performance of the castings at low cost and high efficiency.

[0039] The method of this invention can significantly optimize the distribution of Fe element and the morphology of iron-rich phase in aluminum alloys, improve the overall strength and toughness of the material, provide a technical solution for the application of medium-to-high Fe content aluminum alloys, reduce material costs, and improve green recycling efficiency.

[0040] This invention provides a method for controlling the iron-rich phase in extruded aluminum alloys. The method primarily uses an Al-TiB2 controlling alloy to regulate the morphology and distribution of the iron-rich phase in the extruded aluminum alloy. It mainly includes two steps: The Al-TiB2 controlling alloy preparation method involves adding KBF4 and K2TiF6 to an aluminum alloy melt at 840℃~860℃, controlling the Ti and B element contents to 3wt.%~5wt.% and 1wt.%~3wt.%, respectively, ensuring that the total amount of unavoidable impurity elements in the melt does not exceed 0.4wt.%, and cooling the melt to 750℃~780℃ when the melt conductivity reaches 50%IACS~60%IACS for later use; The iron-rich phase control treatment method involves adding the Al-TiB2 controlling melt to the extruded aluminum alloy melt at a ratio of 0.2wt.%~1wt.%, rotating and blowing at a speed of 200r / min~300r / min for 1min~5min, followed by a standing treatment for 3min~5min, and then extruding and casting the alloy. This method can synergistically achieve the effects of iron-rich phase regulation, microstructure refinement, and second-phase strengthening, thereby comprehensively improving the preparation quality and mechanical properties.

[0041] It should be noted that the reaction temperature for preparing Al-TiB2 controlled melt in this invention is between 840℃ and 860℃. When the reaction temperature is too high, the reaction process may be difficult to control, resulting in larger TiB2 particles, which will affect the control effect of TiB2 particles. When the reaction temperature is too low, the in-situ reaction rate will be reduced, which may lead to incomplete reaction, thereby reducing the yield of Ti and B elements and affecting the accuracy of the mass fraction of TiB2 particles in the final melt.

[0042] It should be noted that this invention controls the Ti / B element mass ratio to below 2.4, especially below 2.2, thereby making the B element in the melt excessive. The presence of excessive trace amounts of B element will optimize the size and morphology of TiB2 particles, thereby improving its control effect on the Fe-rich phase in the alloy.

[0043] The technical solution of the present invention will be further described below through specific embodiments.

[0044] In the following embodiments, unless otherwise specified, the methods described are conventional methods; and unless otherwise specified, the reagents and materials described are commercially available.

[0045] Example 1 A method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers includes the following steps: Step 1, Preparation of Al-TiB2 Regulated Melt: KBF4 was added to the aluminum melt to achieve a B content of 2 wt.% in the regulated melt. When the melt temperature reached 850℃, K2TiF6 was added until the Ti content in the regulated melt reached 4.1 wt.%, and the temperature was maintained at 850℃ for 60 min. The melt with added B and Ti was then subjected to multi-stage rotary blowing refining, followed by a settling treatment. After the conductivity of the Al-TiB2 regulated melt reached 57% IACS, the temperature was lowered to 750℃ to obtain the Al-TiB2 regulated melt.

[0046] Step 2, AlSi 10 MgFe 0.5 After the aluminum alloy is completely melted, it is subjected to 20 minutes of rotary blowing to remove gas and slag, and then allowed to stand for 20 minutes. Al-TiB2, accounting for 0.3 wt.% of the aluminum alloy melt, is added to regulate the melt. After 3 minutes of rotary blowing at 250 r / min, it is allowed to stand for 3 minutes. Then, it is extruded and cast under forming conditions of 100 MPa forming pressure and 1.0 m / s speed.

[0047] Comparative Example 1 A method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers includes the following steps: AlSi 10 MgFe 0.5 After the aluminum alloy is completely melted, it is subjected to rotary blowing at 250 r / min for 20 min to remove gas and slag, and then left to stand for 20 min. After rotary blowing for 3 min, it is left to stand for 3 min, and then extruded and cast under forming pressure of 100 MPa and forming speed of 1.0 m / s.

[0048] Comparative Example 2 A method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers includes the following steps: AlSi 10 MgMnFe 0.5 After the aluminum alloy is completely melted, it is subjected to rotary blowing at 250 r / min for 20 min to remove gas and slag, and then left to stand for 20 min. After rotary blowing for 3 min, it is left to stand for 3 min, and then extruded and cast under forming pressure of 100 MPa and forming speed of 1.0 m / s.

[0049] Test 1: The effect of different control methods on the mechanical properties of castings.

[0050] Aluminum alloy extrusion casting test bars were prepared according to the methods of Example 1 and Comparative Examples 1 to 2, and the mechanical properties of the aluminum alloy extrusion casting test bars were tested. The results are shown in Table 1.

[0051] Table 1 Mechanical properties of aluminum alloy extrusion cast test bars As can be seen from the results in Table 1, in terms of mechanical properties, compared with the untreated aluminum alloy in Comparative Example 1, the aluminum alloy extrusion casting test bar obtained by using the control method of Example 1 of the present invention has significantly improved mechanical properties, especially the elongation is increased by more than 1 times.

[0052] Meanwhile, compared with the traditional Mn alloying method of Comparative Example 2, the aluminum alloy extrusion casting test bar obtained by using the control method of Example 1 of the present invention has significantly improved tensile strength, yield strength and elongation.

[0053] As can be seen from the above analysis, compared with the traditional Mn alloying method, the control method of Example 1 of the present invention, by controlling the addition of Al-TiB2 to the melt, can effectively improve the mechanical properties of the prepared aluminum alloy extrusion casting test bar.

[0054] Test 2: The effects of different control methods on Fe element distribution and Fe-rich phase.

[0055] Figure 1 The figures show the Fe element distribution in the matrix specimen prepared by the method of Comparative Example 1 and the Al-TiB2-added aluminum alloy extrusion casting specimen prepared by the method of Example 1. (a) shows the Fe element distribution in the matrix specimen prepared by the method of Comparative Example 1; (b) shows the Fe element distribution in the Al-TiB2-added aluminum alloy extrusion casting specimen prepared by the method of Example 1. (a1) is a cross-sectional view of the matrix test bar prepared by the method of Comparative Example 1; (a2) is a Fe element distribution diagram of the longitudinal section of the matrix test bar prepared by the method of Comparative Example 1; (a3) ​​is a Fe element signal intensity distribution diagram of the longitudinal section of the matrix test bar prepared by the method of Comparative Example 1; (b1) is a cross-sectional view of the longitudinal section of the aluminum alloy extrusion casting test bar with Al-TiB2 added prepared by the method of Example 1; (b2) is a Fe element distribution diagram of the longitudinal section of the aluminum alloy extrusion casting test bar with Al-TiB2 added prepared by the method of Example 1; (b3) is a Fe element signal intensity distribution diagram of the longitudinal section of the aluminum alloy extrusion casting test bar with Al-TiB2 added prepared by the method of Example 1.

[0056] Depend on Figure 1 It can be seen that, compared with Comparative Example 1, the Fe element distribution of the Al-TiB2-added aluminum alloy extrusion casting test bar prepared by the method of Example 1 is more uniform.

[0057] Figure 2 The microstructure of the iron-rich phase microstructure of the aluminum alloy extrusion casting specimen with Al-TiB2 added, prepared by the method of Example 1, is shown by scanning electron microscopy backscattered electron microscopy. Figure 3The backscattered electron phase of the iron-rich phase microstructure of the matrix specimen prepared by the method of Comparative Example 1 is shown in the scanning electron microscope.

[0058] Depend on Figure 2 and Figure 3 The comparison revealed that, compared with Comparative Example 1, the Fe-rich phase of the aluminum alloy extrusion casting test bar prepared by the method of Example 1 of the present invention was significantly broadened, and a transformation from needle-like to plate-like structures occurred.

[0059] The test results above demonstrate that the control method of Example 1 of this invention, by controlling the addition of Al-TiB2 to the melt, can significantly improve the morphology and distribution of the iron-rich phase in the as-cast microstructure of aluminum alloys under medium-high Fe content conditions, and reduce the adverse effects of the iron-rich phase. Moreover, while affecting the iron-rich phase, the introduced TiB2 particles can simultaneously exert a refining and modifying effect through uniform nucleation and a strengthening effect through the second phase, resulting in a more superior synergistic control effect on the as-cast microstructure.

[0060] Example 2 A method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers differs from the method in Example 1 in that the mass ratio of B to Ti is 1:2.2. The specific method includes the following steps: Step 1, Preparation of Al-TiB2 Regulated Melt: KBF4 was added to the aluminum melt to achieve a B content of 1.9 wt.%. When the melt temperature reached 850℃, K2TiF6 was added until the Ti content reached 4.2 wt.%. The melt was held at 850℃ for 60 min. The melt with added B and Ti was then subjected to multi-stage rotary blowing refining, followed by a settling process. After the conductivity of the Al-TiB2 regulated melt reached 55% IACS, the temperature was lowered to 750℃ to obtain the Al-TiB2 regulated melt.

[0061] Step 2, AlSi 10 MgFe 0.5 After the aluminum alloy is completely melted, it is subjected to 20 minutes of rotary blowing to remove gas and slag, and then allowed to stand for 20 minutes. Al-TiB2, accounting for 0.3 wt.% of the aluminum alloy melt, is added to regulate the melt. After 3 minutes of rotary blowing at 250 r / min, it is allowed to stand for 3 minutes. Then, it is extruded and cast under forming conditions of 100 MPa forming pressure and 1.0 m / s speed.

[0062] Table 2. Feeding conditions for different mass ratios of B and Ti elements. Test 3: The longitudinal sections of the extruded aluminum alloy test bars with Al-TiB2 added, prepared by the methods of Examples 1 and 2, and the matrix test bar prepared by the method of Comparative Example 1, were observed to investigate the effect of different mass ratios of B to Ti on the size and morphology of Al-TiB2 particles. The results are as follows: Figure 4 .

[0063] Figure 4 These are longitudinal cross-sectional views of aluminum alloy extrusion casting test bars with Al-TiB2 added, prepared by different mass ratios of B and Ti elements. Among them, (a) is a longitudinal cross-sectional view of the matrix test bar prepared by the method of Comparative Example 1; (b) is a longitudinal cross-sectional view of the aluminum alloy extrusion casting test bar with Al-TiB2 added prepared by the method of Example 1; and (c) is a longitudinal cross-sectional view of the aluminum alloy extrusion casting test bar with Al-TiB2 added prepared by the method of Example 2.

[0064] Depend on Figure 4 The results showed that, compared with Comparative Example 1, Examples 1 and 2 of this invention, by controlling the mass ratio of B to Ti elements at 1:1.9 to 2.4 during the preparation process, not only ensured the stability and repeatability of the reaction, but also directly affected the size and morphology of the generated TiB2 particles. Specifically, with the increase of Ti content, the TiB2 particles gradually grew into larger plate-like shapes, and the size of the TiB2 particles was submicron, approximately 0.1 μm to 3 μm. These submicron-sized particles not only could be uniformly dispersed in the aluminum alloy matrix through rotary spraying, but also provided a higher surface area, enhancing the refining effect.

[0065] Example 3 A method for controlling the iron-rich phase in aluminum alloys based on TiB2-based process optimizers differs from the method in Example 1 in that the amount of Al-TiB2-controlled melt added accounts for 0.6 wt.% of the mass of the aluminum alloy melt; the specific method includes the following steps: Step 1, Preparation of Al-TiB2 Regulated Melt: KBF4 was added to the aluminum melt to achieve a B content of 2 wt.%. When the melt temperature reached 850℃, K2TiF6 was added until the Ti content reached 4.1 wt.%. The melt was held at 850℃ for 60 min. The melt with added B and Ti was then subjected to multi-stage rotary blowing refining, followed by a settling process. After the conductivity of the Al-TiB2 regulated melt reached 57% IACS, the temperature was lowered to 750℃ to obtain the Al-TiB2 regulated melt.

[0066] Step 2, AlSi 10 MgFe 0.5After the aluminum alloy is completely melted, it is subjected to 20 minutes of rotary blowing to remove gas and slag, and then allowed to stand for 20 minutes. Al-TiB2, accounting for 0.6 wt.% of the aluminum alloy melt, is added to regulate the melt. After 3 minutes of rotary blowing at 250 r / min, it is allowed to stand for 3 minutes. Then, it is extruded and cast under forming conditions of 100 MPa forming pressure and 1.0 m / s speed.

[0067] Example 4 A method for controlling the iron-rich phase in aluminum alloys based on TiB2-based process optimizers differs from the method in Example 1 in that the amount of Al-TiB2-controlled melt added accounts for 1.0 wt.% of the mass of the aluminum alloy melt; the specific method includes the following steps: Step 1, Preparation of Al-TiB2 Regulated Melt: KBF4 was added to the aluminum melt to achieve a B content of 2 wt.% in the regulated melt. When the melt temperature reached 850℃, K2TiF6 was added until the Ti content in the regulated melt reached 4.1 wt.%, and the temperature was maintained at 850℃ for 60 min. The melt with added B and Ti was then subjected to multi-stage rotary blowing refining, followed by a settling treatment. After the conductivity of the Al-TiB2 regulated melt reached 57% IACS, the temperature was lowered to 750℃ to obtain the Al-TiB2 regulated melt.

[0068] Step 2, AlSi 10 MgFe 0.5 After the aluminum alloy is completely melted, it is subjected to 20 minutes of rotary blowing to remove gas and slag, and then allowed to stand for 20 minutes. Al-TiB2, accounting for 1.0 wt.% of the aluminum alloy melt, is added to regulate the melt. After 3 minutes of rotary blowing at 250 r / min, it is allowed to stand for 3 minutes. Then, it is extruded and cast under forming conditions of 100 MPa forming pressure and 1.0 m / s speed.

[0069] Test 4: The effect of different amounts of melt added on the mechanical properties of aluminum alloy extrusion casting test bars.

[0070] Aluminum alloy extrusion casting test bars were prepared according to the methods of Comparative Example 1, Example 1, Example 3 and Example 4, and the mechanical properties of the aluminum alloy extrusion casting test bars were tested. The results are shown in Table 3.

[0071] Table 3. Effects of different melt addition amounts on the mechanical properties of aluminum alloy extrusion-cast test bars. As shown in Table 3, the embodiments of the present invention, by controlling the mass ratio of Al-TiB2 melt to aluminum alloy melt to 0.3%–1%, can significantly improve the mechanical properties of extruded aluminum alloy test bars. This is mainly because the introduced TiB2 particles can control the morphology and distribution of the iron-rich phase in the product, thereby significantly improving the microstructure and overall properties of extruded aluminum alloys with medium to high Fe content. Moreover, while affecting the iron-rich phase, the introduced TiB2 particles can also simultaneously exert a refining effect through uniform nucleation and a strengthening effect through the second phase, achieving a more superior synergistic control effect on the as-cast microstructure.

[0072] Therefore, by adding Al-TiB2 to regulate the melt, the embodiments of the present invention can significantly improve the size and morphology of the iron-rich phase, provide effective nucleation sites, promote grain refinement and regulation of the iron-rich phase, thereby significantly improving the mechanical properties of aluminum alloy extrusion casting test bars.

[0073] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers, characterized in that, Includes the following steps: A B source is added to the aluminum melt, and a Ti source is added at 840℃~860℃. After heat treatment, a multi-stage rotary blowing refining process is carried out to obtain an Al-TiB2 controlled melt. The mass ratio of B to Ti is 1:1.9~2.

4. Al-TiB2 modulating melt is added to aluminum alloy melt, and after rotary blowing refining, it is extruded and cast to achieve control over the morphology and distribution of iron-rich phase in extruded aluminum alloy; the amount of Al-TiB2 modulating melt added accounts for 0.1% to 1% of the mass percentage of aluminum alloy melt.

2. The method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers according to claim 1, characterized in that, In the Al-TiB2 controlled melt, B accounts for 1% to 3% of the mass percentage of the Al-TiB2 controlled melt; Ti accounts for 3% to 5% of the mass percentage of the Al-TiB2 controlled melt.

3. The method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers according to claim 1, characterized in that, The B source is KBF4; the Ti source is K2TiF6.

4. The method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers according to claim 1, characterized in that, After multi-stage rotary jet refining, the process also includes: static treatment, followed by cooling to 750℃~780℃ when the conductivity of the melt is controlled by Al-TiB2 at 50%IACS~60%IACS.

5. The method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers according to claim 1, characterized in that, The parameters for extrusion casting are: forming pressure of 80MPa~140MPa and forming speed of 0.04m / s~1.0m / s.

6. The method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers according to claim 1, characterized in that, The aluminum alloy is an aluminum alloy with an iron content of 0.4 wt.% to 0.5 wt.%.

7. The method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers according to claim 6, characterized in that, The aluminum alloy is an aluminum-silicon based cast aluminum alloy.

8. The method for controlling the iron-rich phase of aluminum alloys based on TiB2-based process optimizers according to claim 1, characterized in that, The temperature for heat preservation is 840℃~860℃; the heat preservation time is 60min~90min.

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