A method for preparing aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material

Abstract

The invention provides a preparation method of an aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material. In the preparation method of the aluminum-iron-copper series high thermal conductivity aluminum alloy material provided by the invention, the formula, in terms of mass percentage, comprises: Si≤0.5%; Fe: 1.0-2.0%; Cu: 0.7-2.0%; Mn≤0.05%; Mg≤0.05%; Zn≤0.05%; Ti≤0.05%; Ni≤0.05%; TCB seed alloy addition amount: 0.1-0.6%; Sr: 0.0005-0.06%; Pb≤0.05%; Sn≤0.01%; Cd≤0.01%; a single common impurity element is ≤0.05%, and the total impurity content is ≤0.15%; the rest is Al; and the preparation method comprises the following steps: adding an aluminum ingot, an iron agent, a copper agent, a preheated aluminum-strontium master alloy and a TCB seed, and casting the aluminum ingot within the range of 720±10°C. The high thermal conductivity aluminum alloy material prepared by the preparation method of the aluminum-iron-copper series high thermal conductivity aluminum alloy material provided by the present invention has relatively excellent die-casting performance, can realize die-casting molding of products containing thin walls, and also has relatively high electrical and thermal conductivity and good heat resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of die-cast aluminum alloys, and in particular relates to a method for preparing an aluminum-iron-copper series high thermal conductivity die-cast aluminum alloy material. Background Art

[0002] The thermal conductivity of pure aluminum is about 237W / (mk). The thermal conductivity of almost all aluminum alloy materials is lower than that of pure aluminum. This is because the addition of any element to the alloy has a greater or lesser negative impact on the thermal conductivity of the material.

[0003] In addition to considering mechanical properties and thermal conductivity, die-casting aluminum alloys also need to consider their die-casting properties. In terms of die-casting properties, the aluminum-silicon series is the best, and the eutectic type is the best. Therefore, the current research and development of high thermal conductivity die-casting aluminum alloys is mainly focused on the aluminum-silicon series. The thermal conductivity of die-casting aluminum alloy materials has developed from 120-130W / (mk) in the early days to 150-160W / (mk) and then to 170-180W / (mk) in recent years, and has made great progress.

[0004] For example, patent publication number CN115948682A discloses a high thermal conductivity aluminum alloy material suitable for 5G large thin-walled heat dissipation cavity. It is characterized by the following components, calculated by mass percentage: Si8-9%; Fe0.6-1.0%; Mg0.1-0.3%; Sr0.02-0.05%; the remainder is Al and unavoidable impurities. This invention belongs to the aluminum silicon system, requires rare earth refining, and rheological die casting, and then heat treatment. The thermal conductivity of the die casting after heat treatment is about 180W / (mk).

[0005] Patent publication number CN117187630A discloses a high thermal conductivity die-cast aluminum alloy product and its preparation method and heat sink. It is characterized in that, by mass percentage, it includes the following components: Si7.5-9.0%; Fe0.70-0.95%; Cu<0.02%; Mg:<0.02%; Mn<0.01%; Cr<0.01%; Ti<0.01%; V<0.01%; Sr0.02-0.04%; the remainder is Al and impurity elements. This invention also belongs to the aluminum silicon system, and its die-casting performance is good. The thermal conductivity of the die-casting can reach 180W / (mk) after heat treatment. However, the material has strict requirements on the content of impurity elements and requires heat treatment, which has high production costs.

[0006] Patent Publication No. CN117363934A Low-titanium and low-vanadium hypoeutectic high thermal conductivity Al-Si alloy material and its preparation method. It is characterized in that, by mass percentage, it includes the following components: Si6.5-8.5%; Fe0.65-0.8%; Mg: 0.05-0.15; Sr0.008-0.02%; RE0.01-0.05%; B0.008-0.015%; Ti<0.001%; ​​V<0.002%; the total amount of other impurity elements does not exceed 0.15%, a single impurity element does not exceed 0.05%, and the balance is Al. This invention also belongs to the aluminum-silicon system, and its die-casting performance is good. The thermal conductivity of the aluminum alloy material can reach 180W / (mk). The alloy needs to regulate the Ti and V elements within a relatively low range.

[0007] In summary, the high thermal conductivity die-cast aluminum alloy materials currently developed are mainly concentrated in Al-Si alloys. The alloys have very strict requirements on impurity elements such as V, Ti, and Cr, which requires the alloy to have a high purity. Existing Al-Si die-cast aluminum alloy materials usually add an appropriate amount of iron to avoid sticking, or add a small amount of copper to improve the mechanical properties of the material. However, iron and copper elements will form complex multi-component compounds in Al-Si die-cast aluminum alloy materials, which have a great negative impact on the thermal conductivity of the material, causing the thermal conductivity of the material to decrease. Therefore, the thermal conductivity of Al-Si die-cast aluminum alloys, especially eutectic Al-Si die-cast aluminum alloy materials, is difficult to exceed 180W / (mk). In order to obtain higher thermal conductivity, it is necessary to achieve it through heat treatment.

[0008] With the continuous development and progress of science and technology, the thermal conductivity of aluminum-silicon alloy materials can no longer meet the market demand. At present, China has also conducted research on non-aluminum-silicon series high thermal conductivity die-casting aluminum alloy materials and achieved some results. For example:

[0009] Patent publication number CN108130456A discloses a high thermal conductivity die-cast aluminum alloy material and a preparation method thereof, characterized in that, by mass percentage, it includes the following components: Si<0.2%, Fe0.8-1.8%, Ni0.2-0.8%, La0.1-0.4%, Mg<0.2%, Cu<0.2%, Mn<0.2%, Zn<0.2%, Co≤0.3%, Pb≤0.1%, Sn≤0.01%, the total amount of other impurities does not exceed 0.3%, and the balance is Al. The thermal conductivity of this invention can reach 220W / (mk), and the thermal conductivity is very excellent. However, it belongs to the AlFeNi series, and the direct effect of nickel on the fluidity of aluminum liquid is relatively small. Therefore, the fluidity of this alloy material is poor, and the die-casting performance is general. It can only die-cast simple die-casting parts with thick walls (such as fire distributors, etc.), and it is difficult to form workpieces with thin walls and high teeth. And it contains precious metal Ni, and the production cost is high.

[0010] CN108929975A discloses an aluminum alloy material and a preparation method thereof, characterized in that, by mass percentage, it includes the following components: Si2.0-4.5%, Fe0.6-1.5%, Cu<0.3%, Mn<0.3%, Mg<0.3%, Zn<0.3%, Ni0.2-1.2%, Pb≤0.1%, Sn≤0.01%, Cd≤0.01%, and the balance is Al. The invention has good thermal conductivity and high temperature resistance. It has very good heat resistance and can reach a heat resistance test of 550℃*3 hours, but its thermal conductivity is still difficult to break through 180W / (mk), and it belongs to the AlSiFeNi system, has poor fluidity, and general die-casting performance. It is difficult to form workpieces with thin walls and high teeth to be die-cast, and it also contains precious metal Ni, and the production cost is high.

[0011] Therefore, for some products with thin walls and high-temperature operation, there is a lack of better basic alloy materials, and there is a lack of a die-casting aluminum alloy material that can smoothly die-cast thin-walled and high-tooth workpieces, and has a thermal conductivity of more than 180W / (mk), good high-temperature resistance, and low cost. Summary of the invention

[0012] In view of the deficiencies in the prior art, the present invention provides a method for preparing an aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material having excellent die-casting performance, good thermal conductivity, good electrical conductivity and good heat resistance.

[0013] In the preparation method of the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material provided by the present invention, the formula of the aluminum-iron-copper series high thermal conductivity aluminum alloy material includes, by mass percentage, Si≤0.5%; Fe: 1.0-2.0%; Cu: 0.7-2.0%; Mn≤0.05%; Mg≤0.05%; Zn≤0.05%; Ti≤0.05%; Ni≤0.05%; TCB seed alloy addition amount: 0.1-0.6%; Sr: 0.0005-0.06%; Pb≤0.05%; Sn≤0.01%; Cd≤0.01%; a single common impurity element is ≤0.05%, and the total impurity content is ≤0.15%; the rest is Al;

[0014] The aluminum alloy material is prepared according to the formula, and the preparation method includes the following steps:

[0015] S1. Add part of the aluminum ingot, melt it and heat it to 850-900℃, add the iron agent several times, let it stand for 5-30 minutes after each addition, and stir it for 2-20 minutes;

[0016] S2. Add the preheated copper agent, let it stand for 5-30 minutes, and stir for 2-20 minutes;

[0017] S3. Add the remaining aluminum ingots and adjust the aluminum liquid temperature to 740-760°C;

[0018] S4, refining with a refining agent, removing slag, when the aluminum liquid temperature is 720-750°C, adding preheated aluminum strontium master alloy and TCB seed crystals in sequence;

[0019] S5. The aluminum liquid temperature is within the range of 720±10℃ for casting aluminum ingots.

[0020] Preferably, the TCB seed crystal comprises, by mass percentage, Ti: 1.8-2.2%, C: 0.28-0.35%, B: 0.28-0.35%, Mn: ≤0.1%, Fe: ≤0.3%, Si: ≤0.3%, V: ≤0.1%, and the rest is Al.

[0021] Preferably, the copper agent is red copper or Al-Cu master alloy.

[0022] Preferably, in step S4, the specific steps of refining with a refining agent are: using argon or nitrogen as a carrier gas, adding a refining agent in an amount of 0.1-0.2% of the total amount of the aluminum liquid, and performing refining and purification.

[0023] Preferably, in step S4, the specific steps of slag removal are: removing the surface slag for the first time after refining and purification, controlling the temperature of the aluminum liquid to 740-760°C, and removing the slag for the second time after degassing with argon or nitrogen for 10-30 minutes.

[0024] Preferably, in step S4, before adding the aluminum-strontium master alloy and the TCB seed crystal, the following step is also included: checking the pinholes, which are required to reach level 1.

[0025] Preferably, in step S5, during the casting process, argon or nitrogen is used to pass through a gas-permeable brick with a pore size of 15-25 μm at the bottom of the filter box or flow trough for online degassing, and it is ensured that the pinhole is not higher than level 2.

[0026] Preferably, the main components and process conditions of the aluminum alloy material satisfy the functional relationship described by the following mathematical model:

[0027] Y k =129.482+7.42a+31.505b+7.613c-46.378d

[0028] Y Q =60.143+4.83a+14.983b–3.592c+125.73d

[0029] Y S =19.538-3.303a–2.591b-3.304c+2.166d

[0030] Y Y =26.542+5.911a+9.53b–6.96c+66.956d

[0031] Y D =32.288–1.11a–2.174b+2.38c–3.207d

[0032] Y R =8.013Y D –20.208

[0033] Wherein, a, b, c, d represent the contents of Fe, Cu, TCB seeds and Sr in the formula respectively, and Y K is the tensile strength, Y Q is the yield strength, Y S is the elongation, Y Y is the hardness, Y D is the conductivity, Y R is the thermal conductivity.

[0034] Preferably, in step S1, the iron agent is added in multiple times, and after each addition, the mixture is allowed to stand for 10-20 minutes and stirred for 5-10 minutes.

[0035] Preferably, in step S2, the preheated copper agent is added, and after addition, the mixture is allowed to stand for 10-20 minutes and stirred for 5-10 minutes.

[0036] The high thermal conductivity aluminum alloy material prepared by the preparation method of the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material provided by the present invention has excellent die-casting performance, can realize die-casting of products containing thin walls, and also has high electrical and thermal conductivity and good heat resistance. In terms of its die-casting performance, it is closer to the die-casting performance of aluminum silicon alloy, and can smoothly die-cast to obtain a workpiece containing thin walls. In terms of its thermal conductivity, it breaks through the bottleneck of the thermal conductivity of aluminum silicon alloy. Therefore, the high thermal conductivity aluminum alloy material prepared by the present invention provides a basic material for processing workpieces that require thin-wall die-casting and require a higher thermal conductivity, and the improvement of the basic material provides more possibilities for back-end manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and other purposes, features and advantages of the present invention will become more clear by more specific description of the preferred embodiments of the present invention shown in the accompanying drawings. The same reference numerals indicate the same parts in all the accompanying drawings, and the accompanying drawings are not deliberately scaled to the actual size, and the focus is on illustrating the main purpose of the present invention.

[0038] Figure 1 This is a photo of the heat sink formed by die-casting of the aluminum alloy material prepared in Example 1. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0040] The embodiment of the present invention provides a method for preparing an aluminum-iron-copper series high thermal conductivity die-cast aluminum alloy material. The formula of the aluminum-iron-copper series high thermal conductivity die-cast aluminum alloy material is as follows in terms of mass percentage:

[0041] By mass percentage, Si≤0.5%; Fe: 1.0-2.0%; Cu: 0.7-2.0%; Mn≤0.05%; Mg≤0.05%; Zn≤0.05%; Ti≤0.05%; Ni≤0.05%; TCB seed alloy addition amount: 0.1-0.6%; Sr: 0.0005-0.06%; Pb≤0.05%; Sn≤0.01%; Cd≤0.01%; each common impurity element is ≤0.05%, and the total impurity content is ≤0.15%; the rest is Al.

[0042] According to the above ratio, the aluminum alloy material is prepared in the following steps:

[0043] S1. Add part of the aluminum ingot, melt it and heat it to 850-900℃, add the iron agent several times, let it stand for 5-30 minutes after each addition, and stir it for 2-20 minutes;

[0044] S2. Add the preheated copper agent, let it stand for 5-30 minutes, and stir for 2-20 minutes;

[0045] S3. Add the remaining aluminum ingots and adjust the aluminum liquid temperature to 740-760°C;

[0046] S4, refining with a refining agent, removing slag, when the aluminum liquid temperature is 720-750°C, adding preheated aluminum strontium master alloy and TCB seed crystals in sequence;

[0047] S5. The aluminum liquid temperature is within the range of 720±10℃ for casting aluminum ingots.

[0048] The aluminum-iron-copper series high thermal conductivity die-cast aluminum alloy material prepared by the preparation method of the embodiment of the present invention has excellent die-casting molding performance, and it can realize that it contains multiple relatively thin heat dissipation fins, which can be die-casted relatively smoothly. The aluminum-iron-copper series high thermal conductivity die-cast aluminum alloy material prepared by the present invention has a casting thermal conductivity of 208.159W / (mk) and a casting electrical conductivity of 28.67MS / m in the material casting state. In the die-casting state, the thermal conductivity of the die-casting reaches 195.764W / (mk), the electrical conductivity of the die-casting reaches 26.96MS / m, and it can pass the heat resistance test: 500℃*3 hours without deformation or discoloration. The aluminum-iron-copper series high thermal conductivity die-cast aluminum alloy material prepared by the present invention can realize better die-casting molding containing multiple relatively thin heat dissipation fins, and provide a basic die-casting material for workpieces containing thin walls and needing to work at high temperatures. It breaks through the bottleneck of thermal conductivity of aluminum-silicon alloy materials with good die-casting performance.

[0049] In aluminum-silicon alloy materials, the addition of iron and copper elements forms Al-Si-Fe-Cu alloys, which often have a greater negative impact on the thermal conductivity and electrical conductivity of the alloy material. In the aluminum-iron-copper die-casting aluminum alloy material of the present invention, the silicon content is controlled within a relatively low proportion range, and an aluminum-iron-copper alloy material is formed by an appropriate amount of iron and copper elements. In this material system, the addition of iron and copper is not easy to form a complex multi-component compound, which will not have a greater negative impact on the thermal conductivity of the material, and will not significantly reduce the thermal conductivity of the material. The aluminum-iron-copper die-casting aluminum alloy material can maintain a higher thermal conductivity and can greatly play the role of iron and copper elements.

[0050] The alloy material prepared by the present invention is an aluminum-iron-copper die-casting aluminum alloy material. Through research, it is found that iron and copper in the system will not have a significant negative impact on the thermal and electrical conductivity of the material. Therefore, iron and copper are selected as the main elements of the aluminum alloy, which not only solves the problem of good die-casting formability and mechanical properties of the material, but also ensures the high thermal conductivity of the material.

[0051] First, the Fe content near the Al-Fe eutectic point is selected. The solid solubility of iron in the aluminum alloy system is small, which causes small lattice distortion of the aluminum matrix, so the negative impact on its thermal conductivity is also small. If the amount of iron added is appropriate, it will not affect the thermal conductivity of aluminum much, so that the aluminum alloy material can maintain good thermal and electrical conductivity. In addition, the addition of an appropriate amount of iron content can ensure that the aluminum liquid has good fluidity and provide the aluminum alloy material with excellent die-casting molding performance.

[0052] Secondly, add a proper amount of Cu element. The negative impact of copper element in this system is also small, and it will not affect the thermal conductivity of aluminum much, so that the aluminum alloy material can maintain good thermal and electrical conductivity. At the same time, add a proper amount of Cu element, which is dissolved in the aluminum matrix, and can improve the strength and hardness of the alloy. In addition, the addition of copper can reduce the melting point and viscosity of the aluminum alloy, which is conducive to the flow of aluminum liquid, and can further enhance the excellent die-casting molding performance of the aluminum alloy material, and further ensure that the die-casting aluminum alloy material prepared by the present invention can simultaneously achieve high thermal conductivity and can die-cast thin-walled workpieces with a certain tooth height.

[0053] Based on the research on the different effects of Fe and Cu on thermal conductivity and electrical conductivity in different aluminum alloy systems, the inventor found that the negative effects of Fe and Cu in the Al-Fe-Cu system are much smaller than those in the Al-Si-Fe-Cu system. Therefore, Fe and Cu are selected as the main alloying elements to form the high thermal conductivity die-casting aluminum alloy of the Al-Fe-Cu system. The inventor mainly studied and compared the following aspects:

[0054] 1. Phase stability and structure: In Al-Fe-Cu alloys, Fe and Cu can form a solid solution that is limitedly dissolved in the aluminum matrix. Although this will also increase lattice distortion, compared to Al-Si-Fe-Cu alloys, due to the lack of strong influence of silicon, the formation of intermetallic compounds is less, so the negative impact on thermal conductivity and electrical conductivity is relatively small. In Al-Si-Fe-Cu alloys, when the silicon content is high, silicon compounds and eutectic phases are easily formed. The thermal and electrical conductivity of these phases are usually poor, and Si, Fe, and Cu also form more complex intermetallic compounds. The appearance of these compounds significantly reduces the thermal conductivity and electrical conductivity of the alloy.

[0055] 2. Lattice constant and atomic size: The atomic radius of Si (0.118nm) is quite different from that of aluminum (0.143nm). When Si is added to the Al matrix, due to its large atomic radius difference, the lattice constant will increase, which is more likely to cause lattice distortion and increased dislocations, leading to serious lattice disorders, thereby hindering the transmission of electrons and phonons and reducing the thermal and electrical conductivity of the alloy. Although Fe and Cu will also cause certain lattice distortion, the atomic radius of Fe (0.126nm) and Cu (0.128nm) is slightly different from that of aluminum, so their influence is relatively small compared to that of Si. Therefore, in Al-Fe-Cu alloys, the influence on thermal conductivity and electrical conductivity is not so significant.

[0056] 3. Phase interfaces and defects: In Al-Si-Fe-Cu alloys, the addition of Si often leads to the generation of a large number of phase interfaces, which will become the center of electron and phonon scattering, reducing thermal and electrical conductivity. However, the intermetallic compounds formed by Fe and Cu in Al-Fe-Cu alloys are relatively stable and evenly dispersed, which relatively reduces the number of large phase interfaces and defects, and therefore has a less negative impact on thermal and electrical conductivity.

[0057] 4. Solubility and phase composition: In Al-Si-Fe-Cu alloys, Si has limited solubility in aluminum and will precipitate quickly in a supersaturated state to form a second phase with low thermal conductivity and low electrical conductivity. In Al-Fe-Cu alloys, Fe and Cu can form a good solid solution in aluminum at appropriate contents. Although some intermetallic compounds are also formed, their negative impact on thermal conductivity and electrical conductivity is relatively less than that of Si.

[0058] Therefore, the reason why the influence of Fe and Cu on thermal and electrical conductivity in Al-Si-Fe-Cu alloys is greater than that in Al-Fe-Cu alloys is mainly because the addition of Si changes the microstructure of the alloy and enhances the negative effects of Fe and Cu on thermal and electrical conductivity. In Al-Fe-Cu alloys without Si, the influence of Fe and Cu depends more on their own solubility, phase formation and influence on the lattice structure.

[0059] The addition of different Sr is mainly used to adjust and balance the relationship between several properties (especially mechanical properties).

[0060] In a preferred embodiment, the TCB seed crystal comprises, by mass percentage, Ti: 1.8-2.2%, C: 0.28-0.35%, B: 0.28-0.35%, Mn: ≤0.1%, Fe: ≤0.3%, Si: ≤0.3%, V: ≤0.1%, and the rest is Al.

[0061] The purpose of adding a certain amount of TCB seed alloy is to refine the α-Al phase, solve the problems of uneven grain size and composition segregation, reduce metallurgical defects of the material, and improve and stabilize the thermal conductivity, comprehensive mechanical properties and product quality of the material.

[0062] In a preferred embodiment, the copper agent is red copper or Al-Cu master alloy.

[0063] In a preferred embodiment, the formula of the aluminum-iron-copper series high thermal conductivity aluminum alloy material of the present invention contains 1.5-2.0% Fe.

[0064] In a preferred embodiment, in the formula of the aluminum-iron-copper series high thermal conductivity aluminum alloy material of the present invention, Si≤0.1%.

[0065] In a preferred embodiment, in the formula of the aluminum-iron-copper series high thermal conductivity aluminum alloy material of the present invention, Cu: 1-2.0%.

[0066] In a preferred embodiment, in step S4, the specific steps of refining with a refining agent are: using argon or nitrogen as a carrier gas, adding a refining agent in an amount of 0.1-0.2% of the total amount of the aluminum liquid, and performing refining and purification.

[0067] In a preferred embodiment, in step S4, the specific steps of slag removal are: removing the surface slag for the first time after refining and purification, controlling the temperature of the aluminum liquid to 740-760°C, and removing the slag for the second time after degassing with argon or nitrogen for 10-30 minutes.

[0068] In a preferred embodiment, in step S4, before adding the aluminum-strontium master alloy and the TCB seed crystal, the following step is also included: checking the pinholes, which are required to reach level 1.

[0069] In a preferred embodiment, in step S5, the casting process uses argon or nitrogen to pass through a gas-permeable brick with a pore size of 15-25 μm to perform online degassing at the bottom of the filter box or flow channel, and ensure that the pinhole is no higher than level 2.

[0070] In a preferred embodiment, the main components and process conditions of the aluminum alloy material satisfy the functional relationship described by the following mathematical model:

[0071] Y k =129.482+7.42a+31.505b+7.613c-46.378d

[0072] Y Q =60.143+4.83a+14.983b–3.592c+125.73d

[0073] Y S =19.538-3.303a–2.591b-3.304c+2.166d

[0074] Y Y =26.542+5.911a+9.53b–6.96c+66.956d

[0075] Y D =32.288–1.11a–2.174b+2.38c–3.207d

[0076] Y R =8.013Y D –20.208

[0077] Where: a, b, c, d represent the contents of Fe, Cu, TCB seeds and Sr in the formula respectively, Y K is the tensile strength (MPa), Y Q is the yield strength (MPa), Y S is the elongation (%), Y Y is the hardness (HBW), Y D is the conductivity (MS / m), Y R is the thermal conductivity (W / (mk)).

[0078] The preparation method of the aluminum-iron-copper series high thermal conductivity die-cast aluminum alloy material provided in this embodiment is formed by studying the influence and effect of Fe and Cu elements on the performance of the aluminum alloy material of the present invention and comparing with the Al-Si-Fe-Cu series, and forming a preparation method of a high thermal conductivity die-cast aluminum alloy material based on the Al-Fe-Cu series, and conforming to the above mathematical model within the controlled range. In the model, the standard deviation of the influence of each variable on the performance within the controlled range falls within ±2σ. In the preparation method provided in this embodiment, the composition of the material used and the specific performance of the material satisfy the above functional relationship.

[0079] In the process of developing new aluminum alloy materials, the basic components are often designed by studying the characteristics of each element, and then experiments are carried out in conjunction with specific processes to achieve the performance or performance combination goals of the newly developed materials. Since the effects of elements and their interactions on performance, especially on multiple performance indicators, are often different, some are positively correlated, some are negatively correlated, some have large effects, and some have small effects, the analysis is relatively complicated. The applicant disclosed a design method for alloy material development in a patent with application number 201910476108.0 and publication number CN110232233B, entitled: A design method for die-casting aluminum alloy materials. The composition ratio of the die-casting aluminum alloy with the required specific performance can be designed, and quantifiable process parameters can also be designed. On this basis, the applicant found through further research that the formula content used in the preparation method of the aluminum-iron-copper high thermal conductivity die-casting aluminum alloy material provided by the present invention and the required performance meet the above functional relationship. Within the controlled range of this material, the thermal conductivity is positively correlated with the electrical conductivity, and can simultaneously ensure a good thermal conductivity and a high electrical conductivity. When the material prepared by the preparation method provided by the present invention can still maintain a high level of electrical conductivity after surface treatment, it shows that the aluminum alloy material of the present invention exhibits excellent electrical conductivity and thus also has excellent thermal conductivity which is positively correlated therewith.

[0080] In a preferred embodiment, in step S1, the iron agent is added in multiple times, and after each addition, the mixture is allowed to stand for 10-20 minutes and stirred for 5-10 minutes.

[0081] In a preferred embodiment, in step S2, the preheated copper agent is added, and the mixture is allowed to stand for 10-20 minutes and stirred for 5-10 minutes.

[0082] The aluminum-iron-copper series high thermal conductivity aluminum alloy material prepared by the present invention can be die-casted by the following method:

[0083] (1) The aluminum melt temperature (remelting temperature) before die casting is ≤760℃.

[0084] (2) The temperature of die-casting aluminum liquid is 715±10℃. The wall thickness of die-casting parts is on the lower limit, and the wall thickness of die-casting parts is on the upper limit.

[0085] (3) Die casting mold temperature is 200±10℃. The die casting wall thickness is on the lower limit, and the die casting wall thickness is on the upper limit.

[0086] (4) Degas the aluminum melt with argon or nitrogen for 20-30 minutes before die casting. Remove the slag after degassing.

[0087] (5) During the die-casting process, do not add return materials or other cold materials into the furnace to avoid contamination of the melt.

[0088] (6) Iron tools need to be coated and dried to prevent aluminum melt from being inhaled during the die-casting process.

[0089] In order to have a further understanding and recognition of the technical solution of the present invention, several preferred embodiments are listed and described in further detail.

[0090] Embodiment 1:

[0091] Calculated by mass percentage: Si: 0.032%; Fe: 1.5%; Cu: 1.31%; Mn: 0.0068%; Mg: 0.0022%; Zn: 0.0102%; Ti: 0.014%; B: 0.0042; Ni: 0.0047%; Sr: 0.0007%; Pb: 0.0034%; Sn: 0.0048%; Cd: 0.0001%; ​​TCB seed alloy addition amount: 0.3%; single common impurity element ≤0.05%, total impurity content ≤0.15%; the rest is Al.

[0092] According to the above ratio, the aluminum alloy is prepared in the following steps:

[0093] (1) Clean the furnace bottom and walls to avoid impurities; add 88% aluminum ingots, turn on the fire to melt and heat to 885℃.

[0094] (2) When the temperature is 885°C, add the iron agent in 4 portions. After each addition, let it stand for 15 minutes and stir for 8 minutes.

[0095] (3) Add the preheated copper agent (red copper), let it stand for 15 minutes and stir for 8 minutes.

[0096] (4) Take samples for testing, and proceed to the next step if the ingredients are qualified.

[0097] (5) Add the remaining aluminum ingots and adjust the aluminum liquid temperature to 756°C.

[0098] (6) Nitrogen is used as the carrier gas, and a refining agent is added at a rate of 0.15% of the total amount of the aluminum liquid for refining and purification.

[0099] (7) Remove surface scum for the first time.

[0100] (8) The aluminum liquid temperature is 752℃. After 25 minutes of nitrogen degassing, the surface slag is removed for the second time and the pinholes are checked to reach level 1.

[0101] (9) When the aluminum liquid temperature is 740℃: add the preheated aluminum-strontium master alloy and TCB seed crystals in turn and let it stand for 8 minutes.

[0102] (10) The aluminum liquid temperature is cast at 725℃.

[0103] (11) During the casting process, nitrogen is used to pass through a 15-25 μm pore size air-permeable brick at the bottom of the filter box for online degassing, and ensure that the pinhole is no higher than level 2.

[0104] Embodiment 2:

[0105] Calculated by mass percentage: Si: 0.06%; Fe: 1.97%; Cu: 1.21%; Mn: 0.0088%; Mg: 0.0042%; Zn: 0.0333%; Ti: 0.01%; B: 0.006; Ni: 0.0034%; Sr: 0.0008%; Pb: 0.0036%; Sn: 0.0043%; Cd: 0.0001%; ​​TCB seed alloy addition amount: 0.3%; single common impurity element ≤0.05%, total impurity content ≤0.15%; the rest is Al.

[0106] According to the above ratio, the aluminum alloy is prepared in the following steps:

[0107] (1) Clean the furnace bottom and walls to avoid impurities; add 85% aluminum ingots, turn on the fire to melt and heat to 877℃.

[0108] (2) When the temperature is 877°C, add the iron agent in 4 portions. After each addition, let it stand for 15 minutes and stir for 8 minutes.

[0109] (3) Add the preheated copper agent (red copper), let it stand for 15 minutes and stir for 8 minutes.

[0110] (4) Take samples for testing, and proceed to the next step if the ingredients are qualified.

[0111] (5) Add the remaining aluminum ingots and adjust the aluminum liquid temperature to 758°C.

[0112] (6) Nitrogen is used as the carrier gas, and a refining agent is added at a rate of 0.15% of the total amount of the aluminum liquid for refining and purification.

[0113] (7) Remove surface scum for the first time.

[0114] (8) The aluminum liquid temperature is 753℃. After 25 minutes of nitrogen degassing, the surface slag is removed for the second time and the pinholes are checked to reach level 1.

[0115] (9) When the aluminum liquid temperature is 740℃: add the preheated aluminum-strontium master alloy and TCB seed crystals in turn and let it stand for 8 minutes.

[0116] (10) The aluminum liquid temperature is cast at 728℃.

[0117] (11) During the casting process, nitrogen is used to pass through a 15-25 μm pore size air-permeable brick at the bottom of the filter box for online degassing, and ensure that the pinhole is no higher than level 2.

[0118] Embodiment 3:

[0119] Calculated by mass percentage: Si: 0.028%; Fe: 1.5%; Cu: 1.3%; Mn: 0.0066%; Mg: 0.0039%; Zn: 0.0103%; Ti: 0.014%; B: 0.0039; Ni: 0.0032%; Sr: 0.025%; Pb: 0.0035%; Sn: 0.0042%; Cd: 0.0001%; ​​TCB seed alloy addition amount: 0.3%; single common impurity element ≤0.05%, total impurity content ≤0.15%; the rest is Al.

[0120] According to the above ratio, the aluminum alloy is prepared in the following steps:

[0121] (1) Clean the furnace bottom and walls to avoid impurities; add 87% aluminum ingots, turn on the fire to melt and heat to 891°C.

[0122] (2) When the temperature is 891°C, add the iron agent in 4 portions. After each addition, let it stand for 15 minutes and stir for 8 minutes.

[0123] (3) Add the preheated copper agent (red copper), let it stand for 15 minutes and stir for 8 minutes.

[0124] (4) Take samples for testing, and proceed to the next step if the ingredients are qualified.

[0125] (5) Add the remaining aluminum ingots and adjust the aluminum liquid temperature to 757°C.

[0126] (6) Nitrogen is used as the carrier gas, and a refining agent is added at a rate of 0.15% of the total amount of the aluminum liquid for refining and purification.

[0127] (7) Remove surface scum for the first time.

[0128] (8) The aluminum liquid temperature is 752℃. After 25 minutes of nitrogen degassing, the surface slag is removed for the second time and the pinholes are checked to reach level 1.

[0129] (9) When the aluminum liquid temperature is 742℃: add the preheated aluminum-strontium master alloy and TCB seed crystals in turn and let it stand for 8 minutes.

[0130] (10) The aluminum liquid temperature is cast at 725℃.

[0131] (11) During the casting process, nitrogen is used to pass through a 15-25 μm pore size air-permeable brick at the bottom of the filter box for online degassing, and ensure that the pinhole is no higher than level 2.

[0132] Embodiment 4:

[0133] Calculated by mass percentage: Si: 0.061%; Fe: 1.99%; Cu: 1.20%; Mn: 0.0088%; Mg: 0.0048%; Zn: 0.0392%; Ti: 0.008%; B: 0.0055; Ni: 0.0033%; Sr: 0.012%; Pb: 0.0034%; Sn: 0.0041%; Cd: 0.0001%; ​​TCB seed alloy addition amount: 0.3%; single common impurity element ≤0.05%, total impurity content ≤0.15%; the rest is Al.

[0134] According to the above ratio, the aluminum alloy is prepared in the following steps:

[0135] (1) Clean the furnace bottom and walls to avoid impurities; add 90% aluminum ingots, turn on the fire to melt and heat to 868℃.

[0136] (2) When the temperature is 868°C, add the iron agent in 4 portions. After each addition, let it stand for 15 minutes and stir for 8 minutes.

[0137] (3) Add the preheated copper agent (red copper), let it stand for 15 minutes and stir for 8 minutes.

[0138] (4) Take samples for testing, and proceed to the next step if the ingredients are qualified.

[0139] (5) Add the remaining aluminum ingots and adjust the aluminum liquid temperature to 755℃.

[0140] (6) Nitrogen is used as the carrier gas, and a refining agent is added at a rate of 0.15% of the total amount of the aluminum liquid for refining and purification.

[0141] (7) Remove surface scum for the first time.

[0142] (8) The aluminum liquid temperature is 752℃. After 25 minutes of nitrogen degassing, the surface slag is removed for the second time and the pinholes are checked. The requirement is to reach Level 1.

[0143] (9) When the aluminum liquid temperature is 745℃: add the preheated aluminum-strontium master alloy and TCB seed crystals in turn and let it stand for 8 minutes.

[0144] (10) The aluminum liquid temperature is cast at 727℃.

[0145] (11) During the casting process, nitrogen is used to pass through a 15-25 μm pore size air-permeable brick at the bottom of the filter box for online degassing, and ensure that the pinhole is no higher than level 2.

[0146] Embodiment 5:

[0147] Calculated by mass percentage: Si: 0.0379%; Fe: 1.85%; Cu: 1.28%; Mn: 0.0002%; Mg: 0.0014%; Zn: 0.0211%; Ti: 0.0084%; B: 0.0018; Ni: 0.0031%; Sr: 0.0009; Pb: 0.0032%; Sn: 0.0037%; Cd: 0.0001%; ​​TCB seed alloy addition amount: 0.3%; single common impurity element ≤0.05%, total impurity content ≤0.15%; the rest is Al.

[0148] According to the above ratio, the aluminum alloy is prepared in the following steps:

[0149] (1) Clean the furnace bottom and walls to avoid impurities; add 88% aluminum ingots, turn on the fire to melt and heat to 880℃.

[0150] (2) When the temperature is 880°C, add the iron agent in 4 portions. After each addition, let it stand for 15 minutes and stir for 8 minutes.

[0151] (3) Add the preheated copper agent (red copper), let it stand for 15 minutes and stir for 8 minutes.

[0152] (4) Take samples for testing, and proceed to the next step if the ingredients are qualified.

[0153] (5) Add the remaining aluminum ingots and adjust the aluminum liquid temperature to 756°C.

[0154] (6) Nitrogen is used as the carrier gas, and a refining agent is added at a rate of 0.15% of the total amount of the aluminum liquid for refining and purification.

[0155] (7) Remove surface scum for the first time.

[0156] (8) The aluminum liquid temperature is 751℃. After 25 minutes of nitrogen degassing, the surface slag is removed for the second time and the pinholes are checked. The requirement is to reach Level 1.

[0157] (9) When the aluminum liquid temperature is 743℃: add the preheated aluminum-strontium master alloy and TCB seed crystals in turn and let it stand for 8 minutes.

[0158] (10) The aluminum liquid temperature is cast at 726℃.

[0159] (11) During the casting process, nitrogen is used to pass through a 15-25 μm pore size air-permeable brick at the bottom of the filter box for online degassing, and ensure that the pinhole is no higher than level 2.

[0160] Comparative Example

[0161] Comparative Example 1: The only difference between Comparative Example 1 and Example 1 is that the Fe content of Comparative Example 1 is 0.8%, and the rest of the formula and preparation method are the same as those of Example 1.

[0162] Comparative Example 2: The only difference between Comparative Example 2 and Example 2 is that the Fe content of Comparative Example 2 is 2.5%, and the rest of the formula and preparation method are the same as those of Example 2.

[0163] Comparative Example 3: The only difference between Comparative Example 3 and Example 3 is that the Cu content of Comparative Example 3 is 0.5%, and the rest of the formula and preparation method are the same as those of Example 3.

[0164] Comparative Example 4: The only difference between Comparative Example 4 and Example 4 is that the Cu content of Comparative Example 4 is 2.5%, and the rest of the formula and preparation method are the same as those of Example 4.

[0165] Comparative Example 5: The difference between Comparative Example 5 and Example 5 is that no TCB is added in Comparative Example 5, and the rest of the formula and preparation method are the same as those in Example 5.

[0166] Comparative Example 6: The only difference between Comparative Example 6 and Example 5 is that Si=7.0% is added in Comparative Example 6, and the rest of the formula and preparation method are the same as those in Example 5.

[0167] Comparative Example 7: A380 aluminum alloy material, composition: Cu 3.0-4.0%; Si 7.5-9.5%; Mg ≤ 0.1%; Fe ≤ 2.0%; Zn ≤ 3.0%; Mn ≤ 0.5%; Ni ≤ 0.5%; Sn ≤ 0.35%; Al balance.

[0168] The aluminum alloy materials obtained by casting in Examples 1-5 were tested for cast thermal conductivity, cast electrical conductivity, and cast hardness after casting. The aluminum alloy materials prepared in Examples 1-5 were tested to meet the following properties: cast thermal conductivity ≥ 205W / (mk), cast electrical conductivity ≥ 27.5MS / m, cast hardness ≥ 45HBW, and all passed the heat resistance test: 500℃*3 hours without deformation or discoloration. In the casting state of the material, the thermal conductivity of the casting of Example 1 even reached 208.159W / (mk), and the electrical conductivity of the casting reached 28.67MS / m.

[0169] The alloys of Examples 1-5 were remelted and heat sinks of the same shape were prepared by the die casting method described below, that is, the heat sink blanks with thinner heat sink fins (the shape is as shown in the attached figure). Figure 1 As shown in the figure, it is found that Examples 1-5 can be well formed for die castings with thin walls and high teeth, as shown in the figure. Figure 1 In the figure, the heat sinks die-casted by the aluminum alloy material prepared in Example 1 can be die-casted relatively smoothly. It can be seen that the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material prepared in the present invention has good die-casting performance.

[0170] The alloys of Examples 1-5 and Comparative Examples 1-7 were remelted, and die-casting samples of the same specifications were prepared through a die-casting process. The performance of the die-casting samples after die-casting of the materials prepared in Examples 1-5 and the materials prepared in Comparative Examples 1-6 was tested, and the test results are shown in Table 1.

[0171] The die casting method is as follows:

[0172] (1) The aluminum melt temperature (remelting temperature) before die casting is 750℃.

[0173] (2) The die-casting aluminum liquid temperature is 722°C.

[0174] (3) Die casting mold temperature 205℃.

[0175] (4) Degas the aluminum melt with argon for 25 minutes before die casting. Remove the slag after degassing.

[0176] (5) During the die-casting process, do not add return materials or other cold materials into the furnace to avoid contamination of the melt.

[0177] (6) Iron tools need to be coated and dried to prevent aluminum melt from being inhaled during the die-casting process.

[0178] Table 1

[0179]

[0180] It can be seen from Table 1 that the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material prepared by the present invention, the prepared aluminum alloy die-casting has excellent thermal conductivity and electrical conductivity without heat treatment, and also has high heat resistance.

[0181] In Comparative Example 1, the iron content is low, the strength and hardness of the prepared aluminum alloy material decrease, and the heat resistance becomes poor.

[0182] In Comparative Example 2, the iron content is relatively high, and the electrical conductivity and thermal conductivity of the prepared aluminum alloy material decrease.

[0183] In Comparative Example 3, the copper content is low, and the strength and hardness of the prepared aluminum alloy material decrease. In addition, the low copper content will reduce the fluidity of the alloy material, which is not conducive to the die-casting performance. In particular, when the copper content is less than 0.3, it has no effect on reducing the melting point and viscosity of the aluminum alloy, and cannot improve the fluidity of the aluminum liquid. It is difficult to die-cast products with thin walls.

[0184] In Comparative Example 4, the copper content is relatively high, the electrical conductivity and thermal conductivity are reduced, and the heat resistance is deteriorated.

[0185] In Comparative Example 5, no TCB was added, and the tensile strength, electrical conductivity and thermal conductivity decreased, and the heat resistance became worse.

[0186] In Comparative Example 6, 7% silicon was added, which exceeded the applicable control range of the model, and the electrical conductivity and thermal conductivity decreased, and the heat resistance became worse.

[0187] The die-casting samples of the materials prepared in Examples 1 to 5 and the materials prepared in Comparative Example 7 were subjected to surface treatment after die-casting.

[0188] Treatment 1: Powder spraying treatment was performed on the surface of the die-casting (film thickness was 70-140 μm). The electrical conductivity of the die-casting samples of the aluminum alloy materials of Examples 1-5 after powder spraying treatment was measured to be greater than 26 MS / m. The electrical conductivity of the die-casting sample of the A380 aluminum alloy material die-casting of Comparative Example 7 was 17.27 MS / m before surface treatment and 15.64 MS / m after powder spraying treatment.

[0189] Treatment 2: The die casting was subjected to chemical nickel treatment (film thickness of 10 μm), and the conductivity of the die casting samples of the aluminum alloy materials of Examples 1-5 was measured to be greater than 25 MS / m after the chemical nickel treatment. The conductivity of the die casting sample of the A380 aluminum alloy material die casting of Comparative Example 7 after the chemical nickel treatment was 14.03 MS / m.

[0190] It can be seen that the alloy material prepared by the present invention still maintains a relatively high level of electrical conductivity after surface treatment, and exhibits significantly higher electrical conductivity than the existing A380 aluminum alloy material, thereby also having excellent thermal conductivity which is positively correlated therewith.

[0191] In summary, it can be seen that the preparation method and formula of the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material prepared by the present invention are reasonable. Through a suitable preparation method, as well as appropriate copper content and iron content, good die-casting performance, mechanical properties, electrical conductivity and heat resistance can be achieved, and it will not have a significant negative impact on the thermal conductivity of the material, so that the aluminum alloy material can have a higher thermal conductivity.

[0192] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing an aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material, characterized in that: The formula of the aluminum-iron-copper series high thermal conductivity aluminum alloy material includes Si≤0.5% by mass percentage; Fe: 1.5-2.0%; Cu: 0.7-1.31%; Mn≤0.05%; Mg≤0.05%; Zn≤0.05%; Ti≤0.05%; Ni≤0.05%; TCB seed alloy addition amount: 0.1-0.6%; Sr: 0.0005-0.06%; Pb≤0.05%; Sn≤0.01%; Cd≤0.01%; each common impurity element≤0.05%, the total impurity content≤0.15%; the rest is Al; The aluminum alloy material is prepared according to the formula, and the preparation method includes the following steps: S1. Add part of the aluminum ingot, melt it and heat it to 850-900℃, add the iron agent several times, let it stand for 5-30 minutes after each addition, and stir it for 2-20 minutes; S2. Add the preheated copper agent, let it stand for 5-30 minutes, and stir for 2-20 minutes; S3. Add the remaining aluminum ingots and adjust the aluminum liquid temperature to 740-760°C; S4, using a refining agent to perform refining and slag removal, when the aluminum liquid temperature is 720-750°C, adding the preheated aluminum-strontium master alloy and TCB seed crystals in sequence; S5. Aluminum ingots are cast within the range of 720±10℃ for molten aluminum temperature; S6, remelting the cast aluminum ingot and then performing die casting, and performing surface treatment on the die casting after die casting, wherein the surface treatment is powder spraying treatment or chemical nickel treatment; The main components and process conditions of the aluminum alloy material satisfy the functional relationship described by the following mathematical model: Y K =129.482+7.42a+31.505b+7.613c-46.378d <h2 style=";text-align:left;direction:ltr">Y<h2 style=";text-align:left;direction:ltr"> Q <h2 style=";text-align:left;direction:ltr"> =60.143+4.83a+14.983b–3.592c+125.73d <h2 style=";text-align:left;direction:ltr">Y<h2 style=";text-align:left;direction:ltr"> S <h2 style=";text-align:left;direction:ltr"> =19.538-3.303a–2.591b-3.304c+2.166d <h2 style=";text-align:left;direction:ltr">Y<h2 style=";text-align:left;direction:ltr"> Y <h2 style=";text-align:left;direction:ltr"> =26.542+5.911a+9.53b–6.96c+66.956d AND D =32.288–1.11a–2.174b+2.38c–3.207d Y R =8.013Y D –20.208 Wherein, a, b, c, d represent the contents of Fe, Cu, TCB seeds and Sr in the formula respectively, and Y K is the tensile strength of the die casting, Y Q is the yield strength of the die casting, Y S is the elongation of the die casting, Y Y is the hardness of the die casting, Y D is the electrical conductivity of the die casting, Y R is the thermal conductivity of the die casting.

2. The method for preparing the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material according to claim 1, characterized in that: The TCB seed crystal comprises, by mass percentage, Ti: 1.8-2.2%, C: 0.28-0.35%, B: 0.28-0.35%, Mn: ≤0.1%, Fe: ≤0.3%, Si: ≤0.3%, V: ≤0.1%, and the rest is Al.

3. The method for preparing the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material according to claim 1, characterized in that: The copper agent is red copper or Al-Cu master alloy.

4. The method for preparing the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material according to claim 1, characterized in that: In step S4, the specific steps of refining with a refining agent are: using argon or nitrogen as a carrier gas, adding a refining agent in an amount of 0.1-0.2% of the total amount of the aluminum liquid, and performing refining and purification.

5. The method for preparing the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material according to claim 1, characterized in that: In step S4, the specific steps of slag removal are: removing the surface slag for the first time after refining and purification, controlling the temperature of the aluminum liquid to 740-760°C, and removing the slag for the second time after degassing with argon or nitrogen for 10-30 minutes.

6. The method for preparing the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material according to claim 1, characterized in that: In step S4, before adding the aluminum-strontium master alloy and the TCB seed crystal, the following steps are also included: checking the pinholes, which are required to reach level 1.

7. The method for preparing the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material according to claim 1, characterized in that: In step S5, during the casting process, argon or nitrogen is used to pass through a gas-permeable brick with a pore size of 15-25 μm at the bottom of the filter box or flow trough for online degassing, and it is ensured that the pinhole is not higher than level 2.

8. The method for preparing the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material according to claim 1, characterized in that: In step S1, the iron agent is added in multiple times, and after each addition, the mixture is allowed to stand for 10-20 minutes and stirred for 5-10 minutes.

9. The method for preparing the aluminum-iron-copper series high thermal conductivity die-casting aluminum alloy material according to claim 1, characterized in that: In step S2, the preheated copper agent is added, and the mixture is allowed to stand for 10-20 minutes and stirred for 5-10 minutes.

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