Screening method for high-temperature-resistant cast aluminum alloy components based on high-throughput calculation

Abstract

The invention discloses a screening method for high-temperature-resistant cast aluminum alloy components based on high-throughput calculation. The screening method comprises the following steps that 1, a calculation model is established, and parameters are set; 2, drawing a thermodynamic phase diagram; 3, setting screening conditions, wherein two screening conditions are met at the same time; and 4, determining a phase component region. The invention discloses a high-temperature-resistant cast aluminum alloy with mechanical and conductive properties. The high-temperature-resistant cast aluminum alloy comprises an alpha-Al phase, an Al13Fe4 phase, an Mg2Si phase, an alpha-AlFeSi phase and a beta-AlFeSi phase, the Al13Fe4 phase and the alpha-AlFeSi phase are thermal stable phases, the Mg2Si phase is a reinforcement body, and the beta-AlFeSi phase is a harmful phase. The invention discloses a preparation method of a high-temperature-resistant cast aluminum alloy with mechanical and conductive properties. The preparation method comprises the following steps: preparing an aluminum alloy melt; preparing an as-cast aluminum alloy; performing heat treatment on the as-cast aluminum alloy; when the material is used as a high-temperature-resistant material, the electric conductivity is kept at 53.8 + / -0.2% IACS (International Annealed Copper Standard) and the hardness is kept at 63.3 + / -1.4 HV when the working temperature is 180 DEG C and the heat preservation time is 150 hours.

Description

Technical Field

[0001] The present invention relates to the technical field of the design of aluminum alloy materials, and particularly relates to a screening method for the components of a high-temperature resistant cast aluminum alloy based on high-throughput calculation. Background Art

[0002] Aluminum alloy materials have excellent casting properties, high specific strength, good corrosion resistance, and excellent electrical and thermal conductivity, and are widely used in the fields of automobiles, aerospace, and mechanical manufacturing. Cast aluminum alloys are widely used in the industrial field and usually meet one of the requirements of mechanical strength, corrosion resistance, or high electrical / thermal conductivity. However, in the technical fields represented by motor rotors, aluminum alloys are required to not only have good electrical conductivity but also have good high-temperature yield strength to prevent deformation and rotational instability caused by insufficient strength in a high-temperature working environment, that is, they need to meet the requirements of both strength and conductivity.

[0003] However, according to the metal electron theory, the electrical conductivity of aluminum is proportional to the free path of electrons, and the key factor affecting the free path of electrons is impurity scattering - the stronger the impurity scattering, the shorter the free path of electrons. Therefore, among aluminum-based metal materials, pure aluminum has the best electrical conductivity. The yield strength of pure aluminum is usually less than 50 MPa, and when pure aluminum is in a high-temperature condition, the strength will further decrease, resulting in increased deformation and thus unable to meet the production requirements of components represented by motors; to solve the strength problem of aluminum-based metal materials under high-temperature conditions, introducing other alloying elements is a common and effective method. However, introducing other alloying elements directly causes impurity scattering, resulting in a decrease in the electrical conductivity of the alloy. Therefore, the current technical problem is that cast aluminum alloys cannot have both high electrical conductivity and high strength under high-temperature conditions.

[0004] To solve the problem of the strength performance degradation of aluminum alloys under high-temperature conditions, experimental methods can be used to introduce high-temperature-stable second phases and refine the grains. For example, in the existing literature 1 (Zhang Xingmeng, CN116875859B, an aluminum alloy material and its preparation method, aluminum alloy for motor rotor, induction AC asynchronous motor and vehicle, 2023-09-05) and the existing literature 2 (Zhang Yizhi, CN113981278B, a high-conductivity heat-resistant die-cast aluminum alloy, 2021-10-13), the centrifugal casting method and the die-casting method were respectively used to prepare aluminum alloys, and technical effects were obtained that the yield strength of the alloy reached 73 MPa, the tensile strength reached 90 MPa, and the electrical conductivity reached 50% IACS at 180 °C, and the electrical conductivity was 50.3% IACS at room temperature, the tensile strength was 196 MPa, and the tensile strength was 184 MPa at 150 °C. In addition to the problems that the mechanical properties and electrical conductivity properties of the existing technology cannot meet the application requirements, there are also technical problems that the composition design of the alloy uses the traditional experimental trial-and-error method, resulting in high overall R & D costs and long R & D cycles.

[0005] To solve the technical problems existing in the above traditional experimental trial-and-error method, machine learning or first-principles calculation methods can be used. Among them,

[0006] The method of machine learning is to extract features from data through algorithms, establish a mathematical model, and use this model to predict unknown data. For example, the existing literature 3 ("Heat-resistant aluminum alloy design using explainable machine learning", Materials & Design, 2024: 113057.) uses the ET model in machine learning to calculate and screen the Al-Ti-V-X quaternary aluminum alloy, achieving a performance of the alloy with a tensile strength of 175 MPa and an elongation of 16.5% at 300 °C. This technical solution shows that machine learning can effectively reduce experimental costs and clarify the contribution of each element to the prediction results. However, since this technical solution is based on input experimental data, there is a problem that the training data samples are not representative, resulting in inaccurate prediction results; in addition, this technical solution also has the technical problem of a long experimental cycle - in the early training process, it is necessary to collect and process 367 entries of data to achieve prediction.

[0007] The method of first-principles calculation is a method for theoretically calculating and predicting the electronic structure, energy, mechanical and thermodynamic properties of substances based on the basic laws of quantum mechanics. For example, the existing literature 4 ("Al 3 Sc and Al 3First-principles Calculation of Thermodynamic Properties of Zr Intermetallic Compounds》Acta Metallurgica Sinica, 2013, 49(04): 501-505) Using first-principles calculations for Al 3 Sc and Al 3 Zr binding energy and formation enthalpy to determine the stability of the metal compound structure, and then by calculating the phonon density of states to determine that there is no significant phonon softening phenomenon in the Brillouin zone, and finally determine that Al 3 Sc and Al 3 Zr maintains good structural stability at high temperatures. The main technical problems of this technical solution are as follows:

[0008] 1. Computational scale limitation. The first-principles method can only handle atomic models with hundreds of atoms or less, and it is difficult to accurately reflect the large-scale phenomena of the complex interactions of multiple phases, defects, and impurities in aluminum alloys;

[0009] 2. Limited prediction of complex chemical compositions. In the prediction of multi-component alloy systems using the first-principles method, due to the difficulty in comprehensively describing the complex interactions between elements, simplified assumptions are required, reducing the accuracy of the prediction results.

[0010] Further analysis shows that Problem 1 and Problem 2 are highly correlated, that is, using first-principles calculations inevitably simplifies the alloy conditions, resulting in deviations from the actual material behavior.

[0011] According to the existing technology, the technical problems to be solved currently are manifested in the following two aspects:

[0012] 1. Improve the prediction accuracy while reducing the amount of experiments;

[0013] 2. Reduce the screening difficulty, screening cycle, and cost. Summary of the Invention

[0014] The purpose of the present invention is to provide a screening method for high-temperature resistant cast aluminum alloy compositions based on high-throughput calculations. Aiming at the existing technical problems, the present invention draws the thermodynamic phase diagram of the Al-Fe-Mg-Si alloy system based on the CALPHAD method, sets screening conditions according to the thermodynamic properties of the designed target alloy, and selects the Al-Fe-Mg-Si high-temperature resistant aluminum-based eutectic multi-component alloy with specific compositions to achieve the following invention purposes,

[0015] 1. Control the phase content in the Al-Fe-Mg-Si alloy, thereby accurately screening the Al-Fe-Mg-Si alloy composition;

[0016] 2. Adjust the ratio of Mg element and Si element to achieve uniform distribution of heat-resistant phases, thereby improving the high-temperature mechanical properties and high-temperature electrical conductivity stability of the alloy.

[0017] Specifically, the basic principle involved in the present invention is as follows:

[0018] 1. According to the performance requirements of the Al-Fe-Mg-Si alloy, combined with the knowledge of the thermodynamic phase diagram, design the thermodynamic properties of the target alloy and set the screening conditions, and select the composition region of the Al-rich corner that simultaneously contains the α-Al phase, Al 13 Fe 4 , α-AlFeSi phase, β-AlFeSi phase, and Mg 2 Si phase. By increasing the multiphase structure, the mechanical properties and electrical conductivity of the alloy are improved;

[0019] 2. Utilize the characteristics that the eutectic Al 13 Fe 4 phase has high thermal stability and heat resistance and strengthens the matrix, and control the content of the Fe element to ensure that the Al 13 Fe 4 phase exists as a eutectic phase. At the same time, the α-Al phase in the Al-Fe-Mg-Si alloy must be the matrix phase, and the molar fraction of the α-Al phase should be greater than 95 mol.%;

[0020] 3. In order to improve the mechanical properties of the Al-Fe-Mg-Si alloy, it can be overcome by controlling the content of the phase with high theoretical heat-resistant strengthening. Specifically, the sum of the three phases of Al 13 Fe 4 , α-AlFeSi phase, and Mg 2 Si phase is required to be greater than 3.8 mol.%. At the same time, in order to ensure the mechanical properties of the alloy, the molar amount of the β-AlFeSi phase is less than 0.19 mol.%.

[0021] To achieve the above-mentioned invention purpose, the present invention adopts the following technical solutions:

[0022] A screening method for the composition of high-temperature resistant cast aluminum alloy based on high-throughput calculation, comprising the following steps:

[0023] Step 1, establishment and parameter setting of the high-throughput calculation model. The high-throughput calculation model includes the selection of the calculation model, the setting of the types and composition ranges of alloy elements, and the setting of the calculation step size. Among them, for the selection of the calculation model, Pandat software is used, and the Scheil-Gulliver model in the PanPhaseDiagram phase diagram module is selected as the calculation model for solidification simulation;

[0024] The calculation step size is set as follows: the calculation step size is 1 wt.%;

[0025] In Step 1, the types and composition ranges of alloying elements are set as follows: the types of alloying elements include Al, Fe, Mg, and Si elements, that is, an Al-Fe-Mg-Si alloy. The mass percentage ranges of the alloying element compositions are as follows: Al: 96.6 - 97.4 wt.%, Fe: 1.8 - 2.1 wt.%, Mg: 0.3 - 0.6 wt.%, and Si: 0.5 - 0.7 wt.%, with a total mass of 100 wt.%.

[0026] Step 2: Draw the thermodynamic phase diagram of the Al-Fe-Mg-Si alloy based on the thermodynamic parameters obtained from the calculation results. First, obtain the thermodynamic property information of the Al-Fe-Mg-Si alloy under various composition conditions through the calculation in Step 1. Then, draw the thermodynamic phase diagram of the Al-Fe-Mg-Si alloy based on the calculated thermodynamic property information.

[0027] The thermodynamic property information includes liquidus temperature, solidus temperature, nucleation temperature of the phase, and molar fraction of the phase.

[0028] Step 3: Set the alloy composition screening conditions. The Al-Fe-Mg-Si alloy includes α-Al phase, Al 13 Fe 4 phase, Mg 2 Si phase, α-AlFeSi phase, and β-AlFeSi phase. Among them, the α-Al phase is the matrix phase, and the Al 13 Fe 4 phase is the eutectic phase; the α-AlFeSi phase is an intermetallic compound, the Mg 2 Si phase is an intermetallic compound, and the β-AlFeSi phase is an intermetallic compound.

[0029] In Step 3, the alloy composition screening conditions simultaneously satisfy the following two screening conditions

[0030] Screening condition 1: At T = MIN(T), f(Al 13 Fe 4 ) + f(α-AlFeSi) + f(Mg 2 Si) > 3.8 mol.%

[0031] Screening condition 2: f(β-AlFeSi) < 0.19 mol.%,

[0032] where f(Al 13 Fe 4 ), f(α-AlFeSi), f(Mg 2 Si), and f(β-AlFeSi) are the molar fractions of the Al 13 Fe 4 phase, α-AlFeSi phase, Mg 2The molar fractions of the Si phase and the β-AlFeSi phase, and MIN(T) is the solidus temperature;

[0033] Step 4, determination of the phase composition region meeting the screening requirements. In the Al-Fe-Mg-Si alloy thermodynamic phase diagram, select the 500°C isothermal section phase diagram. According to the requirements meeting the screening in Step 3, the phase composition region meeting the screening requirements can be determined.

[0034] A high-temperature resistant cast aluminum alloy with both mechanical and electrical conductivity, the mass percentage range of alloying element components is as follows: Al: 96.6 - 97.4 wt.%, Fe: 1.8 - 2.1 wt.%, Mg: 0.3 - 0.6 wt.%, and Si: 0.5 - 0.7 wt.%. The alloy includes the α-Al phase, Al 13 Fe 4 phase, Mg 2 Si phase, α-AlFeSi phase, and β-AlFeSi phase.

[0035] The Al 13 Fe 4 phase is a thermally stable phase, with a size of 100 - 500 nm, showing a dispersed distribution state. Its function is to strengthen the matrix phase and improve the high-temperature stability of the alloy;

[0036] The α-AlFeSi phase is a thermally stable phase, with a size of 1 - 25 μm, showing a fine and dispersed spherical rod-like structure. Its function is to strengthen the matrix phase and improve the high-temperature stability of the alloy;

[0037] The Mg 2 Si phase is a reinforcement, with a size of 100 - 500 nm, showing a fine and dispersed distribution state. Its function is to improve the strength and rigidity of the alloy;

[0038] The β-AlFeSi phase is a harmful phase, with a size of 18 - 40 μm; existing in a thick plate or needle-like form. Its function is to weaken the toughness and strength of the matrix.

[0039] A preparation method of a high-temperature resistant cast aluminum alloy with both mechanical and electrical conductivity, including the following steps:

[0040] Step A, preparation of aluminum alloy melt. For the preparation of aluminum alloy melt, first, prepare raw materials with an Al-Fe-Mg-Si alloy meeting a certain mass ratio. Then, preheat the pit furnace under certain conditions to remove moisture in the furnace. At the same time, preheat pure aluminum at the same preheating temperature. After that, put the preheated pure aluminum into the pit furnace and carry out melting under certain conditions. After the pure aluminum is completely melted, remove the surface scum and oxide skin, add Al-20Fe master alloy, Al-20Si master alloy and Al-50Mg master alloy, and completely immerse them in the aluminum liquid. Finally, after all the alloys are completely melted into a liquid state, carry out static settling to obtain the aluminum alloy melt;

[0041] In the said Step A, the mass percentage range of the Al-Fe-Mg-Si alloy is: Al: 96.6 - 97.4 wt.%, Fe: 1.8 - 2.1 wt.%, Mg: 0.3 - 0.6 wt.% and Si: 0.5 - 0.7 wt.%;

[0042] In the said Step A, the preheating conditions are: the preheating temperature is 200 - 400 °C; the melting conditions are: the melting temperature is 780 - 800 °C; the static settling conditions are: the static settling time is 2 h;

[0043] Step B, preparation of as-cast aluminum alloy. First, wrap the refining agent with aluminum foil and dry it. At the same time, preheat the stainless steel bell jar. Then, press the preheated refining agent to the bottom of the aluminum alloy melt with the preheated stainless steel bell jar under certain conditions for refining and degassing. Finally, after adjusting the casting temperature, pour the refined and degassed aluminum alloy melt into a casting mold with a room temperature mold temperature. After the aluminum alloy melt solidifies and cools, the as-cast aluminum alloy, simply referred to as Al-Fe-Mg-Si-ca, can be obtained;

[0044] In the said Step B, the refining and degassing conditions are: the melt temperature is 750 - 800 °C, and high-purity argon gas is introduced;

[0045] In the said Step B, the casting conditions are: the casting temperature is 740 - 750 °C, the materials of the casting molds are all cast iron, and the casting time is less than 30 s;

[0046] Step C, heat treatment of as-cast aluminum alloy. First, carry out solution treatment on the Al-Fe-Mg-Si-ca obtained in Step 2 under certain conditions. After the solution treatment is completed, carry out water cooling. Then, carry out heat treatment under certain conditions to obtain the heat-treated aluminum alloy Al-Fe-Mg-Si, that is, a high-temperature resistant casting aluminum alloy with both mechanical and electrical conductivity, simply referred to as Al-Fe-Mg-Si-ht;

[0047] In the said Step C, the solution treatment conditions are: the solution treatment temperature is 520 °C, and the solution treatment time is 4 h;

[0048] In the said step C, the heat treatment conditions are that the heat treatment temperature is 180°C and the heat treatment time is 20 - 150 h.

[0049] When an aluminum alloy for high-temperature casting based on high-throughput calculation is used as a high-temperature resistant material, at a working temperature of 180°C and a working time of 150 h, the conductivity remains at 53.8 ± 0.2 IACS and the hardness remains at 63.3 ± 1.4 HV.

[0050] The technical effects of the present invention are known through tests:

[0051] It can be known through SEM detection that the Al-Fe-Mg-Si eutectic multi-component as-cast alloy contains α-Al phase, Al 13 Fe 4 , α-AlFeSi phase, β-AlFeSi phase, Mg 2 Si phase. After statistical analysis by Image Pro plus, the molar fraction of each phase is obtained, and the measured results of the phase composition and the molar fraction of each phase are consistent with the theoretical calculation results.

[0052] It can be known through SEM testing that in the Al-Fe-Mg-Si eutectic multi-component as-cast alloy, the α-Al phase is the matrix phase; Al 13 Fe 4 phase is a fine and dense dispersed phase, the α-AlFeSi phase is a bright white spherical rod-shaped phase with a size of 10 - 22 μm; the β-AlFeSi phase is a strip-shaped phase with a length of 18 - 32 μm, and Mg 2 Si phase is black nanoscale particles with a size of 100 - 500 nm, and Al 13 Fe 4 phase and the α-AlFeSi phase are dispersedly distributed in the α-Al phase.

[0053] It can be known through mechanical property testing that the Al-Fe-Mg-Si eutectic multi-component as-cast alloy has good mechanical properties and high-temperature resistance. The hardness of the as-cast alloy is greater than 55 HV; under the conditions of a working temperature of 180°C and a holding time of 150 h, the hardness still remains at 63.3 ± 1.4 HV, showing high-temperature resistance.

[0054] It can be known through electrical conductivity testing that the Al-Fe-Mg-Si eutectic multi-component alloy has good electrical conductivity and high-temperature electrical stability. Under the conditions of a working temperature of 180°C and a holding time of 150 h, the conductivity remains at 53.8 ± 0.2% IACS, showing high-temperature electrical stability.

[0055] Therefore, the present invention has the following advantages over the prior art:

[0056] 1. According to the thermodynamic phase diagram database of the Al-Fe-Mg-Si alloy system, set screening conditions, delimit the phase composition region, and select Al-Fe-Mg-Si alloys with specific compositions that meet the conditions, which can accurately and efficiently predict the content of each phase, that is, it has effectiveness and accuracy, significantly reducing the screening difficulty, screening cycle and cost;

[0057] 2. Smelt Al-Fe-Mg-Si heat-resistant alloys based on the screening method of the present invention, that is, Al-Fe-Mg-Si eutectic multi-component alloys have good mechanical heat-resistant properties and high-temperature electrical conductivity stability. Description of the Drawings

[0058] Figure 1 It is the 500 °C isothermal section phase diagram and composition region of the Al-rich corner of the Al-Fe-Mg-Si system;

[0059] Figure 2 It is the solidification path of the Al-Fe-Mg-Si alloy corresponding to Example 1 and Example 2 and the change in the molar fraction of the phases of Al 13 Fe 4 、Mg 2 Si, α-AlFeSi, β-AlFeSi and α-Al phases during solidification, where Figure 2 a is Example 1, Figure 2 b is Example 2;

[0060] Figure 3 It is the composition region to which Comparative Example 1 and Comparative Example 2 belong;

[0061] Figure 4 It is the solidification path of the Al-Fe-Mg-Si alloy corresponding to Comparative Example 1 and Comparative Example 2 and the change in the molar fraction of the phases of Al 13 Fe 4 、Mg 2 Si, α-AlFeSi, β-AlFeSi and α-Al phases during solidification; where Figure 4 a is Comparative Example 1, Figure 4 b is Comparative Example 2;

[0062] Figure 5 It is the SEM micrograph of the as-cast and heat-treated alloys of Example 1;

[0063] Figure 6 It is the age hardening curves of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 at 180 °C after solution treatment. Detailed Embodiments

[0064] The present invention will be further described in detail with reference to the embodiments and the accompanying drawings of the specification, but it is not a limitation of the present invention.

[0065] Example 1

[0066] A screening method for the composition of high-temperature resistant cast aluminum alloy based on high-throughput calculation, comprising the following steps:

[0067] Step 1, establishment and parameter setting of the high-throughput calculation model. The high-throughput calculation model includes the selection of the calculation model, the setting of the types and composition ranges of alloying elements, and the setting of the calculation step size. Among them,

[0068] The selection of the calculation model is as follows: Using Pandat software, select the Scheil-Gulliver model in the PanPhaseDiagram phase diagram module as the calculation model for solidification simulation;

[0069] The setting of the types and composition ranges of alloying elements is as follows: The types of alloying elements include Al element, Fe element, Mg element and Si element, that is, Al-Fe-Mg-Si alloy. The mass percentage range of alloying element composition is: Al: 96.6 - 97.4 wt.%, Fe: 1.8 - 2.1 wt.%, Mg: 0.3 - 0.6 wt.%, and Si: 0.5 - 0.7 wt.%, and the total mass is 100 wt.%;

[0070] The setting of the calculation step size is as follows: The calculation step size is all 1 wt.%;

[0071] Step 2, drawing the thermodynamic phase diagram of Al-Fe-Mg-Si alloy based on the thermodynamic parameters obtained from the calculation results. First, obtain the thermodynamic property information of Al-Fe-Mg-Si alloy under various composition conditions through the calculation in Step 1, and then draw the thermodynamic phase diagram of Al-Fe-Mg-Si alloy based on the calculated thermodynamic property information;

[0072] The thermodynamic property information includes liquidus temperature, solidus temperature, nucleation temperature of the phase, and molar fraction of the phase;

[0073] Step 3, setting the alloy composition screening conditions. Al-Fe-Mg-Si alloy includes α-Al phase, Al 13 Fe 4 phase, Mg 2 Si phase, α-AlFeSi phase and β-AlFeSi phase. Among them,

[0074] The α-Al phase is the matrix phase;

[0075] Al 13 Fe 4 phase is the eutectic phase, which has the characteristic of being difficult to dissolve under high-temperature conditions, that is, a thermally stable phase; At the same time, Al 13 Fe 4The phases are dispersed in the aluminum matrix. Therefore, in the target alloy composition, Al 13 Fe 4 phases play a role in strengthening the matrix phase and improving the high-temperature stability of the Al-Fe-Mg-Si alloy. At the same time, Al 13 Fe 4 phases have less negative impact on the free electron movement of the alloy;

[0076] The α-AlFeSi phase is an intermetallic compound, which has the characteristic of being difficult to dissolve under high-temperature conditions, that is, it is a thermally stable phase; at the same time, the α-AlFeSi phase is in a fine and dispersed rod-like structure in the aluminum matrix. Therefore, in the target alloy composition, the α-AlFeSi phase plays a role in strengthening the matrix phase and improving the high-temperature stability of the Al-Fe-Mg-Si alloy. At the same time, the negative impact of the α-AlFeSi phase on the free electron movement of the alloy can be ignored;

[0077] Mg 2 Si phases are intermetallic compounds, which have the characteristics of high melting temperature (1358K), low thermal expansion coefficient (7.5×10 -6 K -1 ) and high Young's modulus (120GPa). They are in a fine and dispersed distribution state in the aluminum matrix. Therefore, Mg 2 Si phases can act as reinforcements, helping to improve the strength and rigidity of the alloy. At the same time, the fine and dispersed distribution state has a negligible negative impact on the free electron movement of the alloy;

[0078] The β-AlFeSi phase is an intermetallic compound with strong brittleness. And in the aluminum matrix, it exists in the form of thick plates or needles. Therefore, the β-AlFeSi phase will cause the phenomenon of splitting the matrix, which directly leads to the following two problems: 1. There is a serious obstacle to the free electron movement, that is, the problem of reducing the electrical conductivity of the aluminum alloy; 2. There is a serious problem of reducing the mechanical properties of the aluminum alloy.

[0079] Based on the basic characteristics of the phase components in the above Al-Fe-Mg-Si alloy, the screening conditions for the target alloy composition are set to simultaneously meet the following two screening conditions:

[0080] Screening condition 1: At T = MIN(T), f(Al 13 Fe 4 ) + f(α-AlFeSi) + f(Mg 2 Si) > 3.8 mol.%,

[0081] Screening condition 2: f(β-AlFeSi) < 0.19 mol.%,

[0082] where f(Al 13Fe 4 )、f(α - AlFeSi), f(Mg 2 Si) and f(β - AlFeSi) are the mole fractions of the Al 13 Fe 4 phase, α - AlFeSi phase, Mg 2 Si phase, and β - AlFeSi phase respectively, and MIN(T) is the solidus temperature;

[0083] Step 4, determination of the phase composition region meeting the screening requirements. In the Al - Fe - Mg - Si alloy thermodynamic phase diagram, select the 500 °C isothermal section phase diagram. According to the screening requirements in Step 3, the phase composition region meeting the screening requirements can be determined. To facilitate the subsequent verification of the effectiveness of the alloy screening method, the phase composition region meeting the screening requirements is named Region 1, and the specific region is as Figure 1 shown.

[0084] To prove the effectiveness of the Al - Fe - Mg - Si alloy screening method, in Region 1, select the Al - 1.8Fe - 0.45Mg - 0.5Si alloy for preparation; among them, the theoretical values of each phase obtained by the screening method of Example 1 are shown in Table 1.

[0085] Table 1 Summary table of the types and mole fractions of phases in the Al - Fe - Mg - Si alloy with theoretical calculations of the thermodynamic phase diagram and actual phases

[0086]

[0087] A preparation method of a high - temperature resistant cast aluminum alloy with both mechanical and electrical conductivity properties specifically includes the following steps:

[0088] Step A, preparation of the aluminum alloy melt. First, select raw materials within Region 1 that meet the condition of a mass ratio of Al - 1.8Fe - 0.45Mg - 0.5Si. Specifically, 3597 g of pure aluminum, 348 g of Al - 20Fe master alloy, 121 g of Al - 20Si master alloy, and 48 g of Al - 50Mg master alloy. Then, preheat the pit furnace at a preheating temperature of 400 °C to remove the moisture in the furnace. At the same time, preheat the pure aluminum at the same preheating temperature. After that, put the preheated pure aluminum into the pit furnace and melt it at a melting temperature of 800 °C. After the pure aluminum is completely melted, remove the surface scum and oxide skin, keep the melt temperature at 800 °C, add the Al - 20Fe master alloy, Al - 20Si master alloy, and Al - 50Mg master alloy, and completely immerse them in the aluminum liquid. Finally, after all the alloys are completely melted into a liquid state, let it stand for 2 h to obtain the aluminum alloy melt;

[0089] Step B: Preparation of as-cast aluminum alloy, including refining, degassing, and casting of the aluminum alloy melt. Specifically, first, wrap the refining agent with aluminum foil and dry it. At the same time, preheat the stainless steel bell jar. Then, while maintaining the melt temperature of the aluminum alloy melt in Step A at 800 °C, introduce high-purity argon gas, and use the preheated stainless steel bell jar to press the preheated refining agent to the bottom of the aluminum alloy melt for refining and degassing. Finally, after adjusting the casting temperature to 745 °C, pour the refined and degassed aluminum alloy melt into a casting mold with a mold temperature of room temperature. After the aluminum alloy melt solidifies and cools, the as-cast aluminum alloy Al-1.8Fe-0.45Mg-0.5Si, simply referred to as Al-Fe-Mg-Si-ca, can be obtained.

[0090] The materials of the casting molds are all cast iron, and the casting time is less than 30 s.

[0091] To prove the microstructure, phase morphology, and distribution of Al-Fe-Mg-Si-ca obtained in Step B, that is, to prove the effectiveness and accuracy of the screening method of the present invention, SEM testing and EDS testing are performed on Al-Fe-Mg-Si-ca obtained in Step B. And under the conditions of a magnification of 200 times and a statistical number of 5 sheets, by statistically analyzing the area ratio of each phase, and calculating the mole fraction according to the area ratio of each phase. The test results are as Figure 5 shown in Table 1, Al-Fe-Mg-Si-ca simultaneously contains α-Al phase, Al 13 Fe 4 phase, α-AlFeSi phase, β-AlFeSi phase, and Mg 2 Si phase. Among them,

[0092] The α-Al phase is the matrix phase, and the Al 13 Fe 4 phase and the α-AlFeSi phase are dispersed in the α-Al phase;

[0093] The Al 13 Fe 4 phase has a fine and dense fiber-dispersed structure in its microstructure;

[0094] The α-AlFeSi phase has a bright white spherical structure or granular structure in its microstructure, with a size of 1-5 μm;

[0095] The Mg 2 Si phase has a nano-particle structure in its microstructure;

[0096] The β-AlFeSi phase has a long strip-shaped needle structure in its microstructure, and the length is 23-42 μm;

[0097] Moreover, the test results show that the measured results of the phase composition and the molar fraction of each phase are consistent with the theoretical calculation results, that is, the screening method of the present invention is effective and accurate.

[0098] Step C, heat treatment of the as-cast aluminum alloy. First, solutionize the Al-Fe-Mg-Si-ca obtained in step B at a solution temperature of 520 °C for 4 h, then perform water cooling after solutionizing, and then perform heat treatment at a heat treatment temperature of 180 °C for 150 h to obtain the heat-treated aluminum alloy Al-Fe-Mg-Si, that is, a high-temperature resistant cast aluminum alloy with both mechanical and electrical conductivity, simply referred to as Al-Fe-Mg-Si-ht.

[0099] To prove the microstructure, phase morphology and distribution of Al-Fe-Mg-Si-ht, that is, to prove the influence of heat treatment on the alloy composition and microstructure, SEM test and EDS test are carried out. The test results are as Figure 5 shown.

[0100] The α-Al phase is the matrix phase, and, Al 13 Fe 4 phases and α-AlFeSi phases are dispersed in the α-Al phase;

[0101] Al 13 Fe 4 phase has a fine and dense fibrous network structure;

[0102] The microstructure of the α-AlFeSi phase is a bright white spherical rod-like structure with a size of 10-22 μm;

[0103] Mg 2 Si phase has a nano-particle structure;

[0104] The microstructure of the β-AlFeSi phase is a long strip-like structure, and, the length is 18-32 μm;

[0105] The test results show that after the heat treatment in step C, in the Al-Fe-Mg-Si alloy, the α-Al phase, Al 13 Fe 4 phase and Mg 2 Si phase have no obvious changes; the α-AlFeSi phase and β-AlFeSi phase change during the heat treatment. Specifically, part of the β-AlFeSi phase transforms into short strip-like α-AlFeSi phase. Therefore, the size of the α-AlFeSi phase increases to 10-22 μm. However, due to the phase transformation and grain size refinement effect during the heat treatment, the change amplitude of the α-AlFeSi phase is small.

[0106] Based on the above phenomena, the following conclusion can be drawn. After the heat treatment in step C, the microstructural stability of the Al-Fe-Mg-Si alloy at high temperatures can be improved, that is, Al-Fe-Mg-Si-ht has good high-temperature resistance.

[0107] To further prove the high-temperature resistance of the Al-Fe-Mg-Si-ca alloy, the electrical conductivity test and hardness test were carried out on the Al-Fe-Mg-Si-ht alloy obtained in step C under high-temperature conditions.

[0108] The results of the electrical conductivity test are as Figure 6 shown. Under the conditions of a working temperature of 180 °C and a holding time of 150 h, the electrical conductivity of the alloy is 53.8 ± 0.2% IACS. The test results show that Al-Fe-Mg-Si-ca has good high-temperature electrical conductivity stability.

[0109] The results of the hardness test are as Figure 6 shown. Under the conditions of a working temperature of 180 °C and a holding time of 150 h, the hardness of the alloy is 63.3 ± 1.4 HV. The test results show that Al-Fe-Mg-Si-ca has good high-temperature mechanical properties.

[0110] Combined with the results of the electrical conductivity test and hardness test, it is proved that Al-Fe-Mg-Si-ca has good high-temperature resistance.

[0111] To prove the effectiveness of the screening method of the present invention, Comparative Example 1, Comparative Example 2 and Example 2 are provided, wherein,

[0112] The alloy composition of Comparative Example 1 belongs to phase composition region 2, that is, the alloy composition that does not meet the screening conditions. Specifically, the alloy composition of Comparative Example 1 is Al-1.8Fe-0.3Mg-0.5Si. The screening conditions are as follows: satisfying screening condition 2: f(β-AlFeSi) < 0.19 mol.%, but not satisfying screening condition 1, that is, at T = MIN(T), f(Al 13 Fe 4 ) + f(α-AlFeSi) + f(Mg 2 Si) < 3.8 mol.%;

[0113] The alloy composition of Comparative Example 2 belongs to phase composition region 3, that is, the alloy composition that does not meet the screening conditions. Specifically, the alloy composition of Comparative Example 2 is Al-1.8Fe-0.45Mg-0.7Si. The screening conditions are as follows: satisfying the screening condition: at T = MIN(T), f(Al 13 Fe 4 ) + f(α-AlFeSi) + f(Mg 2Si)>3.8 mol.%, however, it does not meet Screening Criterion 2, i.e., f(β-AlFeSi) > 0.19 mol.%;

[0114] The alloy composition of Example 2 also belongs to Phase Composition Region 1, i.e., the alloy composition that meets the screening criteria. The specific alloy composition of Example 2 is Al-1.8Fe-0.6Mg-0.5Si.

[0115] Comparative Example 1

[0116] A preparation method of a high-temperature resistant cast aluminum alloy with both mechanical and electrical conductivity. The steps not specifically described are the same as those in Example 1. The differences are as follows: In order to meet Phase Composition Region 2, i.e., to meet the condition of a mass ratio of Al-1.8Fe-0.3Mg-0.5Si, in Step A, the addition amount of pure aluminum is 3606 g, the addition amount of Al-20Fe master alloy is 347 g, the addition amount of Al-20Si master alloy is 121 g, and the addition amount of Al-50Mg master alloy is 32 g. The resulting alloy is abbreviated as Al-Fe-Mg-Si-ca-2.

[0117] The SEM test results of Al-Fe-Mg-Si-ca-2 are shown in Table 1. Al-Fe-Mg-Si-ca-2 contains α-Al phase, Al 13 Fe 4 phase, α-AlFeSi phase, β-AlFeSi phase, and Mg 2 Si phase. The test results show that the measured results of the phase composition and the molar fraction of each phase are consistent with the theoretical calculation results, indicating the effectiveness and accuracy of the screening method of the present invention.

[0118] The conductivity test results of Al-Fe-Mg-Si-ca-2 are shown in Table 2. Under the conditions of a working temperature of 180 °C and a holding time of 150 h, the conductivity is 53.7 ± 0.3% IACS. Comparing with the test results of Example 1, the conductivity of Comparative Example 1 decreased by 0.1% IACS. The reason is that due to the coarsening of the size of the intermetallic compound, the propagation of free electrons is hindered, resulting in a decrease in conductivity.

[0119] The hardness test results of Al-Fe-Mg-Si-ca-2 are shown in Table 2. Under the conditions of a working temperature of 180 °C and a holding time of 150 h, the hardness is 55.5 ± 1.2 HV. Comparing with the test results of Example 2, the hardness of Comparative Example 1 decreased by 7.8 HV. The reason is that the content of heat-resistant strengthening phases in the alloy is insufficient and cannot effectively play a strengthening role.

[0120] Comprehensively comparing Example 1 and Comparative Example 1, it can be seen that the phase composition region has a significant impact on the electrical conductivity and hardness, i.e., when Al13 Fe 4 、 α - AlFeSi and Mg 2 The sum of the three phases of Si is less than 3.8 mol.%, directly resulting in insufficient content of the heat-resistant strengthening phase in the alloy, unable to effectively play a strengthening role, thus significantly reducing the mechanical properties and electrical conductivity of the Al - Fe - Mg - Si alloy.

[0121] Table 2 Summary of the properties of as-cast and heat-treated Al - Fe - Mg - Si alloys

[0122]

[0123] Comparative Example 2

[0124] A preparation method of a high-temperature resistant cast aluminum alloy with both mechanical and electrical conductivity. The steps not specifically described are the same as those in Example 1. The difference lies in that: in order to meet Phase Composition Region 3, that is, to meet the condition of a mass ratio of Al - 1.8Fe - 0.45Mg - 0.7Si, in Step A, the addition amount of pure aluminum is 3556 g, the addition amount of Al - 20Fe master alloy is 348 g, the addition amount of Al - 20Si master alloy is 170 g, and the addition amount of Al - 50Mg master alloy is 48 g. The obtained alloy is abbreviated as Al - Fe - Mg - Si - ca - 3.

[0125] The SEM test results of Al - Fe - Mg - Si - ca - 3 are shown in Table 1. Al - Fe - Mg - Si - ca - 3 contains α - Al phase, Al 13 Fe 4 phase, α - AlFeSi phase, β - AlFeSi phase, and Mg 2 Si phase. The test results show that the measured results of the phase composition and the molar fraction of each phase are consistent with the theoretical calculation results, that is, the screening method of the present invention has effectiveness and accuracy.

[0126] The electrical conductivity test results of Al - Fe - Mg - Si - cast - 3 are shown in Table 2. Under the conditions of a working temperature of 180 °C and a holding time of 150 h, the electrical conductivity is 51.2 ± 0.3% IACS. Compared with the test results of Example 1, the electrical conductivity of Comparative Example 1 decreased by 2.6% IACS. The reason is that due to the coarsening of the size of the β - AlFeSi intermetallic compound, the propagation of free electrons is blocked, reducing the electrical conductivity.

[0127] The hardness test results of Al-Fe-Mg-Si-cast-3 are shown in Table 2. Under the conditions of a working temperature of 180 °C and a holding time of 150 h, the hardness is 61.7 ± 0.5 HV. Comparing with the test results of Example 1, it can be seen that the hardness of Comparative Example 1 decreased by 1.6 HV. The reason is that the molar fraction of the heat-resistant strengthening phase in the alloy is less. At the same time, the β-AlFeSi intermetallic compound cuts the matrix, resulting in a decrease in mechanical properties.

[0128] By comprehensively comparing Example 1 and Comparative Example 2, it can be seen that the phase composition region has a significant impact on the electrical conductivity and hardness, that is, when β-AlFeSi is greater than 0.19 mol.%, it directly causes partial cutting of the alloy matrix and cannot effectively play a strengthening role, thus significantly reducing the mechanical properties and electrical conductivity of the Al-Fe-Mg-Si alloy.

[0129] Example 2

[0130] A preparation method of a high-temperature resistant cast aluminum alloy with both mechanical and electrical conductivity. The steps not specifically described are the same as those in Example 1, except that: under the condition of a mass ratio of Al-1.8Fe-0.6Mg-0.5Si, in step A, the addition amount of pure aluminum is 3588 g, the addition amount of Al-20Fe master alloy is 348 g, the addition amount of Al-20Si master alloy is 121 g, and the addition amount of Al-50Mg master alloy is 64 g. The obtained alloy is abbreviated as Al-Fe-Mg-Si-ca-4.

[0131] The SEM test results of Al-Fe-Mg-Si-ca-4 are shown in Table 1. Al-Fe-Mg-Si-ca-4 contains α-Al phase, Al 13 Fe 4 phase, α-AlFeSi phase, β-AlFeSi phase, and Mg 2 Si phase. The test results show that the measured results of the phase composition and the molar fraction of each phase are consistent with the theoretical calculation results, that is, the screening method of the present invention has effectiveness and accuracy.

[0132] The electrical conductivity test results of Al-Fe-Mg-Si-ca-4 are shown in Table 2. Under the conditions of a working temperature of 180 °C and a holding time of 150 h, the electrical conductivity is 52.5 ± 0.2% IACS;

[0133] The hardness test results of Al-Fe-Mg-Si-ca-4 are shown in Table 2. Under the conditions of a working temperature of 180 °C and a holding time of 150 h, the hardness is 77.1 ± 2.5 HV.

[0134] The test results of Comprehensive Example 1 and Example 2 can prove that the Al-Fe-Mg-Si alloy is located in Composition Region 1, that is, the composition of the Al-Fe-Mg-Si alloy by mass ratio satisfies the composition region of Al: 96.6-97.8 wt.%, Fe: 1.8-2.1 wt.%, Mg: 0.3-0.6 wt.%, and Si: 0.5-0.7 wt.%. The following conclusions exist:

[0135] 1. The screening method of the present invention predicts Al in the Al-Fe-Mg-Si alloy 13 Fe 4 , α-AlFeSi, Mg 2 Si, and the accuracy of the sum of the three-phase contents is 92%;

[0136] 2. The alloy obtained by the screening method of the present invention has the technical effects that the conductivity remains at 53.8±0.2 IACS and the hardness remains at 63.3±1.4 HV at a working temperature of 180°C and a holding time of 150 h.

Claims

1. A screening method for high temperature resistant casting aluminum alloy composition based on high throughput calculation, characterized in that The following steps are involved: Step 1, establishment of a high-throughput calculation model and parameter setting, the high-throughput calculation model includes the selection of a calculation model, the setting of alloy element types and composition ranges, and the setting of a calculation step length, wherein the selection of the calculation model is to use Pandat software and select the Scheil-Gulliver model in the PanPhaseDiagram phase diagram module as the calculation model for solidification simulation; Step 2, drawing a thermodynamic phase diagram of the Al-Fe-Mg-Si alloy based on the thermodynamic parameters obtained from the calculation results. First, the thermodynamic property information of the Al-Fe-Mg-Si alloy under the conditions of each component is obtained by calculation in step 1, and then the thermodynamic phase diagram of the Al-Fe-Mg-Si alloy is drawn according to the thermodynamic property information obtained by calculation; The thermodynamic property information includes liquidus temperature, solidus temperature, nucleation temperature of the phase, and amount fraction of the phase; Step 3: Setting the alloy composition screening conditions. Al-Fe-Mg-Si alloy includes α-Al phase, Al 13 Fe4 phase, Mg2Si phase, α-AlFeSi phase and β-AlFeSi phase, among which α-Al phase is the matrix phase, Al 13 Fe4 phase is eutectic phase; α-AlFeSi phase is intermetallic compound, Mg2Si phase is intermetallic compound, β-AlFeSi phase is intermetallic compound; Step 4, determine the phase composition area that meets the screening requirements. In the Al-Fe-Mg-Si alloy thermodynamic phase diagram, select the 500°C isothermal cross-section phase diagram. Based on meeting the screening requirements of step 3, the phase composition area that meets the screening requirements can be determined.

2. The screening method according to claim 1, characterized in that: The calculation step length is set to be 1 wt.%; In step 1, the types of alloy elements and the range of components are set as follows: the types of alloy elements include Al, Fe, Mg and Si, that is, Al-Fe-Mg-Si alloy, and the mass percentage range of alloy element components is Al: 96.6-97.4wt.%, Fe: 1.8-2.1wt.%, Mg: 0.3-0.6wt.% and Si: 0.5-0.7wt.%, with a total mass of 100wt.%.

3. The screening method according to claim 1, characterized in that: In step 3, the screening conditions of the alloy composition simultaneously meet the following two screening conditions: Screening condition 1, when T = MIN (T), f (Al 13 Fe4)+f(α-AlFeSi)+f(Mg2Si)>3.8mol.% Screening condition 2, f(β-AlFeSi)<0.19mol.% Among them, f(Al 13 Fe4), f(α-AlFeSi), f(Mg2Si) and f(β-AlFeSi) are Al 13 The amount fraction of Fe4 phase, α-AlFeSi phase, Mg2Si phase and β-AlFeSi phase, MIN(T) is the solidus temperature.

4. A high temperature resistant cast aluminum alloy having both mechanical and electrical conductivity properties, characterized in that: The alloy element composition mass percentage range is Al: 96.6-97.4wt.%, Fe: 1.8-2.1wt.%, Mg: 0.3-0.6wt.% and Si: 0.5-0.7wt.%. The alloy includes α-Al phase, Al 13 Fe4 phase, Mg2Si phase, α-AlFeSi phase and β-AlFeSi phase.

5. The high temperature resistant cast aluminum alloy having both mechanical and electrical conductivity properties according to claim 4, characterized in that: The Al 13 The Fe4 phase is a thermally stable phase with a size of 100-500nm and is dispersed. Its function is to strengthen the matrix phase and improve the high temperature stability of the alloy. The α-AlFeSi phase is a thermally stable phase with a size of 1-25 μm and a fine dispersed ball-and-stick structure, which serves to strengthen the matrix phase and improve the high-temperature stability of the alloy; The Mg2Si phase is a reinforcement, with a size of 100-500nm and a fine dispersed distribution state, and its function is to improve the strength and rigidity of the alloy; The β-AlFeSi phase is a harmful phase with a size of 18-40 μm. It exists in the form of thick laths or needles and has the function of weakening the toughness and strength of the matrix.

6. The high temperature resistant cast aluminum alloy having both mechanical and electrical conductivity properties according to claim 4, characterized in that: When used as a high temperature resistant material, at an operating temperature of 180°C and a holding time of 150h, the conductivity remains at 53.8±0.2%IACS and the hardness remains at 63.3±1.4HV.

7. A method for preparing a high temperature resistant cast aluminum alloy having both mechanical and electrical conductivity properties, characterized in that The following steps are involved: Step A, preparation of aluminum alloy melt, the preparation of aluminum alloy melt, first, prepare raw materials with Al-Fe-Mg-Si alloy meeting a certain mass ratio, then, preheat the pit furnace under certain conditions to remove moisture in the furnace, and at the same time, preheat pure aluminum at the same preheating temperature, then put the preheated pure aluminum into the pit furnace, smelt under certain conditions, after the pure aluminum is completely melted, remove surface slag and oxide scale, add Al-20Fe master alloy, Al-20Si master alloy and Al-50Mg master alloy, and completely immerse in aluminum liquid, finally, after all alloys are completely melted into liquid, let stand, and then obtain aluminum alloy melt; Step B, preparation of cast aluminum alloy, first, wrapping the refining agent with aluminum foil and drying, at the same time, preheating the stainless steel bell jar, then, under certain conditions, using the preheated stainless steel bell jar to press the preheated refining agent to the bottom of the aluminum alloy melt for refining and degassing, finally, after adjusting the casting temperature, pouring the refined and degassed aluminum alloy melt into a casting mold with a mold temperature of room temperature, after the aluminum alloy melt solidifies and cools, a cast aluminum alloy can be obtained, referred to as Al-Fe-Mg-Si-Ca; Step C, heat treatment of the cast aluminum alloy, first, the Al-Fe-Mg-Si-ca obtained in step 2 is solid-dissolved under certain conditions, and then water-cooled. Then, heat treatment is performed under certain conditions to obtain a heat-treated aluminum alloy Al-Fe-Mg-Si, that is, a high-temperature resistant cast aluminum alloy with both mechanical and conductive properties, referred to as Al-Fe-Mg-Si-ht.

8. The preparation method according to claim 7, characterized in that: In the step A, the mass percentage range of the Al-Fe-Mg-Si alloy is 96.6-97.4wt.%, Fe: 1.8-2.1wt.%, Mg: 0.3-0.6wt.% and Si: 0.5-0.7wt.%; In the step A, the preheating condition is that the preheating temperature is 200-400° C.; the smelting condition is that the smelting temperature is 780-800° C.; and the standing condition is that the standing time is 2 hours.

9. The preparation method according to claim 7, characterized in that: In the step B, the refining and degassing conditions are: the melt temperature is 750-800°C, and high-purity argon is introduced; In step B, the casting conditions are as follows: the casting temperature is 740-750° C., the casting mold is made of cast iron, and the casting time is less than 30 seconds.

10. The preparation method according to claim 7, characterized in that: In the step C, the solid solution conditions are: the solid solution temperature is 520°C and the solid solution time is 4h; In the step C, the heat treatment conditions are: the heat treatment temperature is 180° C., and the heat treatment time is 20-150 hours.

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