High-thermal-conductivity low-expansion Al-Ni-Si-based alloy and preparation method thereof

Abstract

The invention belongs to the technical field of cast aluminum alloys, and discloses a high-thermal-conductivity low-expansion Al-Ni-Si-based alloy and a preparation method thereof. The alloy mainly comprises the following components in percentage by mass: 10-30% of Ni, 10-30% of Si, 0-1% of Sr, 0-1% of Sm, 0.01-1% of P and the balance of Al, the contents of Sr and Sm are not 0 at the same time. The invention further discloses a preparation method of the Al-Ni-Si based alloy with high thermal conductivity and low expansion. The method is simple and easy to implement and low in production cost; the obtained alloy has the advantages of high heat-conducting property, low thermal expansion coefficient, better casting property and higher tensile strength, and is suitable for smelting and casting processes. The alloy provided by the invention meets the performance requirements of the aluminum-based alloy for electronic devices and radiators.

Description

Technical Field

[0001] The invention belongs to the technical field of cast aluminum alloys, and in particular relates to a high thermal conductivity and low expansion Al-Ni-Si based alloy and a preparation method thereof. Background Art

[0002] Although integrated circuits are developing towards higher power, higher integration, miniaturization and lightweight, they also bring many new challenges, such as thermal fatigue caused by a sharp increase in heat and thermal fatigue failure caused by mismatched thermal expansion coefficients between materials. Therefore, the demand for low-cost, high-performance thermal management materials and their preparation technologies is becoming increasingly urgent. These materials also need to have lower density. Aluminum alloys and aluminum-based composites have been widely used in many fields due to their excellent performance, and are conducive to product lightweighting and energy conservation and emission reduction. Therefore, the development of lightweight, high thermal conductivity and low expansion aluminum-based alloys is of great significance.

[0003] High Si content Si / Al and high SiC content SiC / Al composite materials are high thermal conductivity and low expansion materials that have attracted much attention in the field of electronic packaging. They are usually prepared by injection molding and powder metallurgy, and have stable performance. However, due to their complex process and coarse structure obtained by ordinary casting process, they are brittle and difficult to meet the processing and use requirements of thermal management devices.

[0004] Chinese invention patent CN115537611B discloses a high thermal conductivity and low expansion Al-Si-Ni based alloy and its preparation method. This patent is to further compound Mg (~1wt%) and Cu (1~3wt%) alloy in an alloy containing high Si (20~30wt%) and high Ni (10~20wt%), and use P to modify primary Si, and obtain a hypereutectic Al-Si-Ni alloy with low thermal expansion coefficient and high thermal conductivity through sub-rapid solidification and heat treatment, which can meet the performance requirements of aluminum-based alloys for electronic packaging. However, despite its low thermal expansion coefficient, its thermal conductivity is only up to 120W / (m·K). How to further improve the thermal conductivity of this material system is more important for further expanding the application prospects of this material in the field of heat dissipation devices. Chinese patent CN103160716A discloses a method for preparing a low expansion and high strength AlN-Si-Al composite material. The invention uses powder metallurgy technology to produce uniform aluminum-based composite materials with granular AlN and Si as reinforcement phases, which have the characteristics of high thermal conductivity and low expansion. However, this method has high requirements on the particle size of raw materials, complex preparation process, and high equipment requirements, so the production cost is high.

[0005] The above patented technology explores the preparation process of high thermal conductivity and low expansion aluminum-based composite materials and high thermal conductivity and low expansion aluminum alloys. Although these materials exhibit good high thermal conductivity and low expansion properties, their preparation process is complicated, requires high-end production equipment, has high manufacturing costs, or the thermal conductivity of the alloy needs to be further improved. The traditional casting method is simple and low-cost, suitable for the preparation of complex parts. Therefore, the development of high thermal conductivity and low expansion Al-based alloys with high alloy components and their ordinary casting molding processes will help meet the current communication, heat dissipation devices and other fields for high thermal conductivity and low expansion cast aluminum alloys and their preparation needs. Summary of the invention

[0006] In order to overcome the shortcomings and deficiencies of the prior art, the present invention aims to develop a high thermal conductivity and low expansion alloy system and a preparation method thereof which is simple in process and suitable for melting and casting processes, namely, a high thermal conductivity and low expansion Al-Ni-Si based casting aluminum alloy and a preparation method thereof.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A high thermal conductivity and low expansion Al-Ni-Si based alloy comprising the following components by mass percentage:

[0009]

[0010] The balance is Al; the contents of Sr and Sm are different and are 0;

[0011] Preferably

[0012]

[0013] The balance is Al;

[0014] More preferably

[0015]

[0016] The balance is Al.

[0017] The method for preparing the high thermal conductivity and low expansion Al-Ni-Si based alloy comprises the following steps:

[0018] (1) preparing an Al-Ni-Si alloy melt;

[0019] (2) subjecting the Al-Ni-Si alloy melt to a microalloying treatment of Sr and / or Sm, and then to a P modification treatment;

[0020] (3) refining and removing slag from the modified aluminum alloy melt, and casting to obtain a casting;

[0021] (4) The casting is subjected to a solid solution treatment to obtain an Al-Ni-Si based alloy with high thermal conductivity and low expansion.

[0022] Step (1) specifically comprises: melting pure aluminum, aluminum-nickel master alloy and aluminum-silicon master alloy, mixing them uniformly, standing them to keep them warm, and obtaining an Al-Ni-Si alloy melt.

[0023] The aluminum-nickel master alloy is Al-20Ni; the aluminum-silicon master alloy is Al-50Si.

[0024] The melting temperature is 750-900° C. The mixing is stirring and mixing; the stirring time is 1-2 minutes. The standing and heat preservation time is 5-20 minutes.

[0025] The microalloying modification treatment in step (2) is to add a master alloy containing Sr and / or Sm into an Al-Ni-Si alloy melt to obtain a microalloyed aluminum alloy melt;

[0026] Specifically, one or both of Al-Sr and Al-Sm master alloys are added to the Al-Ni-Si alloy melt, melted, mixed, and kept still for 3 to 8 minutes to obtain an aluminum alloy melt in which Sr / Sm is modified alone or Sr and Sm are compositely modified; the Al-Sr master alloy is an Al-20Sr master alloy; the Al-Sm master alloy is an Al-20Sm master alloy; before adding the Al-Sr and Al-Sm master alloys to the Al-Ni-Si alloy melt, the scum on the surface of the Al-Ni-Si alloy melt is removed;

[0027] The P modification treatment refers to adding a P-containing master alloy to the melt for modification treatment; specifically, after all the P-containing master alloy is melted, the master alloy is mixed evenly, and the mixture is kept at a temperature for 3 to 8 minutes to obtain an aluminum alloy melt after the P modification treatment.

[0028] The P-containing master alloy is a copper-phosphorus master alloy, such as a Cu-16P master alloy. The copper-phosphorus master alloy has an excellent modification effect in the Al-Si alloy.

[0029] The refining and slag removal refers to adding a refining agent and a slag removal agent, refining and slag removal, and then standing and keeping warm; the refining and slag removal is added by nitrogen blowing method, the commercial brands of the refining agent and the slag removal agent are YT-J-1 and YT-D-4 respectively, the ingredients are prepared in a 1:1 ratio, and then mixed evenly, and the total addition amount is 1% of the weight of the melt; the standing and keeping warm time is 2 to 30 minutes.

[0030] The casting molding refers to casting; before casting, the alloy melt is cooled by 30-80°C but at the same time the temperature of the melt is at or above the liquidus temperature; the out-of-furnace casting temperature is maintained at 700-850°C.

[0031] The solution treatment in step (4) refers to heat treatment at 500-540° C. for 6-8 hours and water quenching.

[0032] In order to better understand the method of the present invention, combined with the elemental properties, solidification properties and preparation process characteristics of the aluminum alloy containing Si, Ni and modified elements, the principle of a high thermal conductivity and low expansion Al-Ni-Si based alloy and its preparation method of the present invention is described as follows:

[0033] Alloy elements and solidification characteristics: The thermal expansion coefficient of the alloy is closely related to the thermal expansion coefficient of the precipitated phase and its volume fraction. Si has a low thermal expansion coefficient. Adding Si to Al will precipitate in the form of elemental Si, which can effectively reduce the overall expansion coefficient of the alloy. The higher the added Si content, the lower the overall expansion coefficient of the alloy. However, with the increase of Si content, the precipitated coarse Si phase will increase the brittleness of the alloy and deteriorate the thermal conductivity and mechanical properties. In the present invention, when the Si content is between 10% and 30%, the alloy can maintain good casting properties. The Ni element has a low solid solubility in aluminum alloys and reacts with Al to form an Al3Ni phase, which has excellent thermal conductivity and a low thermal expansion coefficient. In addition, the addition of Ni elements will react with Al and Si during the solidification process to form a ternary eutectic reaction, which helps to reduce the melting point of the alloy and make the alloy have good casting properties. The addition of Sm elements can enrich the Al3Ni surface, reduce the component supercooling required for the Al3Ni nucleation and growth process, and refine the primary and eutectic Al3Ni phases. The Sr element is enriched on the surface of the primary and eutectic Si phases and is a commonly used effective modifier for the Si phase. The addition of the P element can form fine AlP particles, which serve as heterogeneous nucleation cores of the Si phase and further refine the primary Si phase. Under the formula of the present invention, the synergistic effect of each element makes the aluminum alloy have excellent thermal conductivity, low expansion performance and good mechanical properties.

[0034] Process characteristics: The present invention replaces part of the Si element in the high-content Al-Si alloy with the Ni element with low solid solubility, ensuring that the alloy has excellent properties such as high thermal conductivity, low expansion, and low density while maintaining good casting performance. The Sm element can metamorphose the primary Al3Ni phase, the Sr element can effectively metamorphose the primary and eutectic Si phases, and the P element can form the AlP phase in the aluminum alloy, provide nucleation sites for the primary Si phase, and refine the Si phase. The synergistic effect of these elements effectively regulates the microstructure of the alloy, thereby improving the thermal conductivity and mechanical properties of the alloy, and the low-expansion Si and Al3Ni phases can significantly reduce the overall thermal expansion coefficient of the aluminum alloy. Heat treatment can spheroidize the eutectic phase in the alloy and disperse and precipitate the solid solution atoms in the form of a second phase, thereby further improving the thermal conductivity of the alloy. Hypereutectic Al-Ni-Si alloy is suitable for conventional smelting and casting processes. Compared with spray deposition and powder metallurgy, the preparation process of ordinary metal mold casting is simpler, lower cost, and higher density. Through this casting process, the obtained castings not only have a finer and more uniform structure, but also have excellent thermal conductivity, low expansion performance and good mechanical properties.

[0035] Compared with the existing casting process, it has the following outstanding advantages and beneficial effects:

[0036] (1) Through the combination of ordinary metal mold casting, modification and heat treatment, the aluminum alloy casting structure is refined, and the thermal conductivity and thermal expansion properties are significantly improved. The process parameters can be flexibly adjusted, and the performance and quality of the castings can be controlled and adjusted by optimizing the parameters to achieve customized production, and aluminum alloy castings of various shapes and sizes can be prepared.

[0037] (2) The present invention aims at aluminum alloy for radiator, significantly improves the thermal conductivity and mechanical properties of the alloy by regulating the microstructure, and effectively reduces the thermal expansion coefficient by adding Ni and Si elements, thus achieving the simultaneous optimization of thermal conductivity, thermal expansion and mechanical properties. Compared with the alloy prepared by traditional metal mold casting, the thermal conductivity of the prepared Al-Ni-Si based alloy can reach up to 215.5W / (m·K), and the expansion coefficient can be reduced to 14.0×10 -6 / K, and the alloy has good mechanical properties, with a tensile strength of 188MPa and an elongation of 7.1%.

[0038] (3) The present invention proposes an alloy system having high thermal conductivity, low expansion and good mechanical properties, and suitable for conventional melting and casting processes, and a preparation method thereof. The entire casting process is simple, does not require complex equipment, has low cost and energy consumption, and can ensure high density of the casting, is suitable for batch production and large-scale manufacturing, and can be used to prepare castings of various complex shapes.

[0039] (4) Compared with a high thermal conductivity and low expansion Al-Si-Ni based alloy and its preparation method disclosed in Chinese invention patent CN115537611B, the thermal conductivity reaches more than 200W / (m·K) when the thermal expansion coefficient and mechanical properties are equivalent. At the same time, it has excellent thermal conductivity, thermal expansion and mechanical properties. The preparation process is simpler and can be directly cast without applying other process treatments. It can be used for large-scale mass production of heat dissipation devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The optical microstructure of the Al-10Ni-15Si alloy prepared by ordinary metal mold casting in Comparative Example 1;

[0041] Figure 2 The optical microstructure of the Al-12Ni-13Si alloy prepared by ordinary metal mold casting in Comparative Example 2;

[0042] Figure 3 The optical microstructure of the Al-10Ni-10Si alloy prepared by ordinary metal mold casting in Comparative Example 3;

[0043] Figure 4 is an optical microstructure diagram of the Al-10Ni-15Si alloy modified by Sr alone in Example 1;

[0044] Figure 5 is the optical microstructure of the Al-10Ni-15Si alloy modified by Sm alone in Example 2;

[0045] Figure 6 is an optical microstructure diagram of the composite modified Al-10Ni-15Si alloy in Example 3;

[0046] Figure 7 is an optical microstructure diagram of the composite modified Al-12Ni-13Si alloy in Example 4;

[0047] Figure 8 is an optical microstructure diagram of the composite modified Al-10Ni-10Si alloy in Example 5;

[0048] Fig. 9 XRD diffraction patterns of Al-Ni-Si alloys prepared in Comparative Example 1 and Examples 1 to 3; base corresponds to the Al-10Ni-15Si alloy of Comparative Example 1, 0.1Sr corresponds to the Al-10Ni-15Si-0.1Sr alloy of Example 1, 0.3Sm corresponds to the Al-10Ni-15Si-0.1Sr-0.3Sm alloy of Example 2, and 0.1Sr-0.3Sm corresponds to the Al-10Ni-15Si-0.1Sr-0.3Sm alloy of Example 3. DETAILED DESCRIPTION

[0049] The present invention is described in detail below in conjunction with specific examples, but the embodiments of the present invention are not limited thereto. Taking hypereutectic Al-Si-Ni alloy as an example, the process flow and implementation effect are described based on comparative examples and examples.

[0050] Comparative Example 1: Al-10Ni-15Si alloy

[0051] The alloy prepared in this comparative example is a hypereutectic Al-10Ni-15Si alloy (mass content, Ni 10%, Si 15% throughout the text). Pure aluminum, Al-20Ni, and Al-50Si alloy are used as raw materials for batching, smelting to prepare Al-10Ni-15Si alloy melt, and finally casting. The specific steps and process parameters are as follows:

[0052] (1) Alloy preparation: According to the target composition Al-10Ni-15Si alloy, the pure aluminum, Al-20Ni and Al-50Si master alloy raw materials required to prepare the target alloy are calculated and weighed respectively;

[0053] (2) Alloy smelting: The weighed raw materials are melted in a furnace at a melting temperature of 800°C. After all the raw materials are melted, they are stirred for 2 minutes to make the composition uniform, and then allowed to stand and heat for 5 minutes to obtain the desired Al-10Ni-15Si alloy melt.

[0054] (3) Melt refining and slag removal: remove slag from the surface of the alloy melt melted in step (2), mix the commercially available YT-J-1 refining agent and YT-D-4 slag removal agent in a ratio of 1:1, add the mixture to the alloy melt by nitrogen blowing method for refining and slag removal, and let it stand and keep warm for 10 minutes;

[0055] (4) Melt casting: The melt in step (3) was cooled to 720°C, allowed to stand for 5 minutes, and then cast into a metal mold preheated to 200°C. The size of the casting was 100 mm × 45 mm × 15 mm. The casting was naturally cooled and solidified to obtain a hypereutectic Al-10Ni-15Si alloy casting. Samples were taken from the casting for analysis.

[0056] In order to characterize the microstructure and mechanical / thermal properties of the above alloys, the microstructure of the alloys was observed using an optical microscope (model: Lecia DFC, standard: JB / T7946-2017). The linear expansion coefficient of the alloys was measured using a thermal mechanical analyzer (model: TMA Q400). The thermal conductivity of the alloys was measured using a flash thermal conductivity meter (model: NETZSCHLFA, size: The thermal diffusion coefficient was measured using an electronic universal material testing machine (model: AG-X-100KN, standard: GB / T228-2010). The test methods for thermal conductivity and mechanical properties are described as follows.

[0057] Thermal conductivity test:

[0058] The present invention strictly tests the thermal diffusion coefficient of aluminum alloy according to the test standard ASTME 1461. The test instrument is a Netzsch LFA-457 laser thermal conductivity tester. The sample size is The upper and lower surfaces are polished with 400-grit sandpaper to ensure the parallelism of the sample. Before the thermal diffusion coefficient test, graphite needs to be sprayed on the surface to increase the infrared emissivity of the sample surface and the absorption ratio of light energy. The specific heat of the sample is calculated using the Neumann-Kopp criterion. The density test is carried out using the Archimedes drainage method and the DH-300 density balance according to the national standard GB / T 1423-19. The result of multiplying the above three physical quantities is the thermal conductivity of the alloy. The calculation formula is as follows:

[0059] λ=α·C p ·ρ

[0060] Where λ is the thermal conductivity of the material, W / (m·K); α is the thermal diffusivity of the material, mm 2 / s;C p is the specific heat of the material, J / (g·K); ρ is the density of the material, g / cm 3 .

[0061] Thermal expansion performance test:

[0062] The present invention strictly tests the thermal expansion coefficient of aluminum alloy in accordance with the current national standard GB / T 4339-2008. The test equipment adopts TMA Q400. The test prepares a 15mm×4mm×4mm cuboid sample by wire cutting and turning. The upper and lower cylindrical surfaces are polished with 400-mesh sandpaper to ensure the parallelism of the two end surfaces. In this test, each group of alloys is heated to 250°C at a heating rate of 5°C / min. The computer records the temperature curve of the sample length to obtain the change curve of the thermal expansion coefficient. The specific linear expansion coefficient is as follows:

[0063]

[0064] In the formula, α represents the linear expansion coefficient, K -1 ; Δl represents the change in length, mm; l0 represents the original length of the sample, mm; Δt represents the change in temperature, K.

[0065] Mechanical properties test:

[0066] The present invention conducts mechanical property tests on a Shimadzu AG-X100KN universal testing machine according to the national standard GB / T 228.1. The test sample is processed into a dumbbell shape by wire cutting, and the upper and lower surfaces are polished with 400-mesh sandpaper to eliminate the influence of defects on the experimental results. In this test, each group of alloys is tested 3 times at a tensile speed of 1 mm / min and room temperature (25°C), and the stress-strain curve is recorded to obtain performance data, and the average value is taken as the final test data.

[0067] According to GB / T 228.1 standard, image and data processing are performed to remove the displacement of the sliding part of the clamping section. The gauge length of the sample is 25mm, and the elongation δ is calculated according to the following formula:

[0068]

[0069] Wherein, δ is the elongation, %; l0 is the gauge length of the specimen, mm; l1 is the length of the gauge part of the specimen after breaking, mm.

[0070] Figure 1 The optical microstructure of the Al-10Ni-15Si alloy prepared in Comparative Example 1 is shown in Figure 1. The microstructure of the Al-10Ni-15Si alloy is mainly composed of α-Al, Al3Ni and Si phases. The primary Al3Ni phase is arranged in blocks and strips, and the primary Si phase is distributed in large blocks. The XRD diagram of the alloy in this comparative example is shown in Figure 1. Fig. 9 shown.

[0071] The thermal conductivity of the Al-10Ni-15Si alloy prepared by ordinary metal mold casting in Comparative Example 1 was tested. The thermal conductivity of the alloy prepared by this mixing method was 156.2 W / (m·K), and the thermal expansion coefficient was 14.3×10 -6 K -1 (@100℃). The tensile strength and elongation of the Al-10Ni-15Si alloy under this mixing mode were tested, and the tensile strength was 208MPa and the elongation was 3.9%.

[0072] Comparative Example 2: Al-12Ni-13Si alloy

[0073] The alloy prepared in this comparative example is a hypereutectic Al-12Ni-13Si alloy. The raw materials and specific steps for smelting the alloy are similar to those in comparative example 1, except for the ratio of elements and specific process parameters. The specific steps and process parameters are as follows:

[0074] (1) Alloy preparation: According to the target composition Al-12Ni-13Si alloy, the raw materials of pure aluminum, Al-20Ni and Al-50Si master alloy required to prepare the target alloy are calculated and weighed respectively;

[0075] (2) Alloy smelting: The weighed raw materials are melted in a furnace at a melting temperature of 820°C. After all the raw materials are melted, they are stirred for 2 minutes to make the composition uniform, and then allowed to stand and heat for 5 minutes to obtain the desired Al-12Ni-13Si alloy melt.

[0076] (3) Melt refining and slag removal: remove slag from the surface of the alloy melt melted in step (2), mix the commercially available YT-J-1 refining agent and YT-D-4 slag removal agent in a ratio of 1:1, add the mixture to the alloy melt by nitrogen blowing method for refining and slag removal, and let it stand and keep warm for 10 minutes;

[0077] (4) Melt casting: The melt in step (3) was cooled to 740°C, kept at this temperature for 5 min, and then cast into a metal mold preheated to 200°C. The size of the casting was 100 mm × 45 mm × 15 mm. The casting was naturally cooled and solidified to obtain a hypereutectic Al-12Ni-13Si alloy casting. Finally, samples were taken from the casting for analysis.

[0078] Figure 2 It is an optical microstructure diagram of the Al-12Ni-13Si alloy prepared in Comparative Example 2. Similarly, the microstructure of the Al-12Ni-13Si alloy is mainly composed of α-Al, Al3Ni and Si phases, the primary Al3Ni phase is arranged in blocks and strips, and the primary Si phase is distributed in large blocks.

[0079] The thermal conductivity of the Al-12Ni-13Si alloy prepared by ordinary metal mold casting in Comparative Example 2 was tested. The thermal conductivity of the alloy prepared by this mixing method was 161.1 W / (m·K), and the thermal expansion coefficient was 14.8×10 6 K -1 (@100℃). The tensile strength and elongation of the Al-12Ni-13Si alloy under this mixing mode were tested, and the tensile strength was 205MPa and the elongation was 4.1%.

[0080] Comparative Example 3: Al-10Ni-10Si alloy

[0081] The alloy prepared in this comparative example is a hypereutectic Al-10Ni-10Si alloy. The raw materials and specific steps for smelting the alloy are similar to those in comparative example 1, except for the ratio of elements and specific process parameters. The specific steps and process parameters are as follows:

[0082] (1) Alloy preparation: According to the target composition Al-10Ni-10Si alloy, the raw materials of pure aluminum, Al-20Ni and Al-50Si master alloy required to prepare the target alloy are calculated and weighed respectively;

[0083] (2) Alloy smelting: The weighed raw materials are melted in a furnace at a melting temperature of 850°C; after all the raw materials are melted, they are stirred for 2 minutes to make the composition uniform, and then allowed to stand and heat for 5 minutes to obtain the desired Al-10Ni-10Si alloy melt;

[0084] (3) Melt refining and slag removal: remove slag from the surface of the alloy melt melted in step (2), mix the commercially available YT-J-1 refining agent and YT-D-4 slag removal agent in a ratio of 1:1, add the mixture to the alloy melt by nitrogen blowing method for refining and slag removal, and let it stand and keep warm for 10 minutes;

[0085] (4) Melt casting: The melt in step (3) was cooled to 770°C, allowed to stand for 5 minutes, and then cast into a metal mold preheated to 200°C. The size of the casting was 100 mm × 45 mm × 15 mm. The casting was naturally cooled and solidified to obtain a hypereutectic Al-Ni-Si alloy casting. Samples were taken from the casting for analysis.

[0086] Figure 3 It is an optical microstructure diagram of the Al-10Ni-10Si alloy prepared in Comparative Example 3. The microstructure of the Al-10Ni-10Si alloy is mainly composed of α-Al, Al3Ni and Si phases, the primary Al3Ni phase is arranged in blocks and strips, and the primary Si phase is distributed in blocks.

[0087] The thermal conductivity of the Al-10Ni-10Si alloy prepared by ordinary metal mold casting in Comparative Example 3 was tested. The thermal conductivity of the alloy prepared by this mixing method was 167.0 W / (m·K), and the thermal expansion coefficient was 15.4×10 -6 K -1 (@100℃). The tensile strength and elongation of the Al-10Ni-10Si alloy under this mixing mode were tested, and the tensile strength was 201MPa and the elongation was 4.4%.

[0088] To further illustrate the implementation effect of the present invention, the present invention is described below in conjunction with embodiments.

[0089] Example 1: Preparation of Al-10Ni-15Si-0.1Sr alloy by Sr modification treatment + heat treatment

[0090] The composition and process of preparing the alloy in this embodiment are different from those in Comparative Example 1. The raw materials for preparing the alloy are pure Al, Al-20Ni, Al-50Si and Al-10Sr master alloy, and a heat treatment process is added. The specific steps and process parameters are as follows:

[0091] (1) Alloy preparation: According to the target composition Al-10Ni-15Si-0.1Sr alloy, the raw materials of pure aluminum, Al-20Ni, Al-50Si and Al-20Sr master alloy required to prepare the target alloy are calculated and weighed respectively;

[0092] (2) Alloy smelting: The weighed raw materials are melted in a furnace at a melting temperature of 800°C. After all the raw materials are melted, they are stirred for 2 minutes to make the composition uniform, and then allowed to stand and heat for 5 minutes to obtain the desired Al-10Ni-15Si alloy melt.

[0093] (3) Adding the microalloying element Sr: Add Al-20Sr master alloy to the Al-Ni-Si alloy melt. After the master alloy is completely melted, stir for 2 minutes to make the composition uniform. Let it stand and keep warm for 5 minutes to obtain the aluminum alloy melt after microalloying modification.

[0094] (4) Melt refining and slag removal: remove slag from the surface of the alloy melt melted in step (3), mix the commercially available YT-J-1 refining agent and YT-D-4 slag removal agent in a ratio of 1:1, add the mixture to the alloy melt by nitrogen blowing to perform refining and slag removal, and leave the mixture to stand and keep warm for 10 minutes;

[0095] (5) melt casting: the melt in step (4) was cooled to 720°C, kept at this temperature for 5 minutes, and then cast into a metal mold preheated to 200°C. The size of the casting was 100 mm × 45 mm × 15 mm. The casting was naturally cooled and solidified to obtain a hypereutectic Al-10Ni-15Si alloy casting treated with Sr modification. Samples were taken from the casting for analysis.

[0096] (6) Heat treatment of Al-Ni-Si based alloy castings: The castings obtained in step (5) were subjected to solution treatment (520°C × 6h + water quenching) to obtain Sr modified + heat treated Al-10Ni-15Si alloy.

[0097] The microstructural characteristics of the alloy prepared in this example were observed and analyzed. Figure 4 This is an optical microstructure diagram of the Al-10Ni-15Si alloy modified by Sr + heat treatment in Example 1. Compared with the alloy prepared in Comparative Example 1, in the alloy modified by Sr alone + heat treatment, the coarse primary Si and the long strip-shaped eutectic Si phases are refined, but the primary and eutectic Al3Ni phases remain basically unchanged.

[0098] The XRD pattern of the alloy in this example is as follows: Fig. 9 shown.

[0099] The test results show that the thermal conductivity of the alloy in this embodiment is 190.8 W / (m·K), the tensile strength is 175 MPa, the elongation is 4.8%, and the thermal expansion coefficient is 14.2×10 -6 K -1 (@100°C). Compared with the alloy prepared in Comparative Example 1, the comprehensive performance of the alloy prepared in this embodiment is improved to a certain extent, the thermal conductivity is increased by 22.2%, the tensile strength is reduced to a certain extent, but the thermal conductivity is significantly improved, and the elongation of the alloy is increased by 23.1%, and the thermal expansion coefficient is reduced by 0.7%. Sr modification composite heat treatment improves the microstructure morphology of the Al-10Ni-15Si alloy to a certain extent, and at the same time improves the thermal conductivity and thermal expansion performance of the alloy.

[0100] Example 2: Preparation of Al-10Ni-15Si-0.3Sm alloy by Sm modification treatment + heat treatment

[0101] The preparation process of this embodiment is similar to that of embodiment 1, except that the components of the prepared alloy are different. The raw materials for preparing the alloy are pure Al, Al-20Ni, Al-50Si and Al-20Sm master alloy. The specific steps and process parameters are as follows:

[0102] (1) Alloy preparation: According to the target composition Al-10Ni-15Si-0.3Sm alloy, the raw materials of pure aluminum, Al-20Ni, Al-50Si and Al-20Sm master alloy required to prepare the target alloy are calculated and weighed respectively;

[0103] (2) Alloy smelting: The weighed raw materials are melted in a furnace at a melting temperature of 800°C. After all the raw materials are melted, they are stirred for 2 minutes to make the composition uniform, and then allowed to stand and heat for 5 minutes to obtain the desired Al-10Ni-15Si alloy melt.

[0104] (3) Adding the microalloying element Sm: Add the Al-20Sm master alloy to the Al-10Ni-15Si alloy melt. After the master alloy is completely melted, stir for 2 minutes to make the composition uniform, and keep it at room temperature for 5 minutes to obtain the aluminum alloy melt after microalloying modification.

[0105] (4) Melt refining and slag removal: remove slag from the surface of the alloy melt melted in step (3), mix the commercially available YT-J-1 refining agent and YT-D-4 slag removal agent in a ratio of 1:1, add the mixture to the alloy melt by nitrogen blowing to perform refining and slag removal, and leave the mixture to stand and keep warm for 10 minutes;

[0106] (5) melt casting: the melt in step (4) was cooled to 720°C, kept at this temperature for 5 minutes, and then cast into a metal mold preheated to 200°C. The size of the casting was 100 mm × 45 mm × 15 mm. The casting was naturally cooled and solidified to obtain a hypereutectic Al-10Ni-15Si alloy casting treated with Sm modification. Samples were taken from the casting for analysis.

[0107] (6) Heat treatment of Al-Ni-Si based alloy castings: The castings obtained in step (5) were subjected to solution treatment (520°C × 6h + water quenching) to obtain Al-10Ni-15Si alloy subjected to Sm modification + heat treatment.

[0108] The microstructural characteristics of the alloy prepared in this example were observed and analyzed. Figure 5 This is an optical microstructure diagram of the Al-10Ni-15Si alloy modified by Sm + heat treatment in Example 2. Compared with the alloy prepared in Comparative Example 1, in the alloy modified by Sm alone + heat treatment, the morphology of the coarse primary Si and the long strip-shaped eutectic Si phases does not change much, but the primary and eutectic Al3Ni phases show a more obvious refinement effect.

[0109] The XRD pattern of the alloy in this example is as follows: Fig. 9 shown.

[0110] The test results show that the thermal conductivity of the alloy in this embodiment is 191.7 W / (m·K), the tensile strength is 178 MPa, the elongation is 4.5%, and the thermal expansion coefficient is 14.1×10 -6 K -1 (@100°C). Compared with the alloy prepared in Comparative Example 1, the comprehensive performance of the alloy prepared in this embodiment is improved to a certain extent, with thermal conductivity increased by 22.7%, elongation increased by 15.4%, and thermal expansion coefficient decreased by 1.4%. Sm modification and heat treatment improve the microstructure morphology of the Al-10Ni-15Si alloy to a certain extent, and at the same time improve the thermal conductivity and thermal expansion performance of the alloy.

[0111] Example 3: Preparation of Al-10Ni-15Si-0.1Sr-0.3Sm-0.3P alloy

[0112] The preparation process of this embodiment is similar to that of embodiment 1, except that the components of the prepared alloy are different. The raw materials for preparing the alloy are pure Al, Al-20Ni, Al-50Si, Al-20Sr, Al-20Sm and a P-containing master alloy, and the P-containing master alloy is a Cu-16P master alloy. The specific steps and process parameters are as follows:

[0113] (1) Alloy preparation: According to the target composition Al-10Ni-15Si-0.1Sr-0.3Sm-0.3P alloy (10% Ni, 15% Si, 0.1% Sr, 0.3% Sm, 0.3% P in the alloy, by mass percentage), the raw materials of pure aluminum, Al-20Ni, Al-50Si, Al-20Sr, Al-20Sm and Cu-16P master alloy required to prepare the target alloy were calculated and weighed respectively;

[0114] (2) Alloy smelting: The weighed raw materials are melted in a furnace at a melting temperature of 800°C. After all the raw materials are melted, they are stirred for 2 minutes to make the composition uniform, and then allowed to stand and heat for 5 minutes to obtain the desired Al-Ni-Si alloy melt.

[0115] (3) Adding microalloying elements Sr / Sm / P: Add Al-20Sr and Al-20Sm master alloys to the Al-Ni-Si alloy melt. After the master alloy is completely melted, stir for 2 minutes to make the composition uniform, and keep it at room temperature for 5 minutes to obtain an aluminum alloy melt subjected to microalloying modification.

[0116] (4) P modification treatment: adding CuP master alloy to the aluminum alloy melt in step (3) for modification treatment, maintaining the temperature at 800° C., stirring for 2 min after the Cu-P master alloy is completely melted to make the composition uniform, and standing and keeping the temperature for 5 min to obtain the aluminum alloy melt after P modification treatment;

[0117] (5) Melt refining and slag removal: remove slag from the surface of the alloy melt melted in step (4), mix the commercially available YT-J-1 refining agent and YT-D-4 slag removal agent in a ratio of 1:1, add the mixture to the alloy melt by nitrogen blowing to perform refining and slag removal, and leave the mixture to stand and keep warm for 10 minutes;

[0118] (6) melt casting: the melt in step (5) was cooled to 720°C, kept at this temperature for 5 minutes, and then cast into a metal mold preheated to 200°C. The size of the casting was 100 mm × 45 mm × 15 mm. The casting was naturally cooled and solidified to obtain a hypereutectic Al-10Ni-15Si alloy casting modified by Sr / Sm / P. Samples were taken from the casting for analysis.

[0119] (7) Heat treatment of Al-Ni-Si based alloy castings: The castings obtained in step (6) were subjected to solution treatment (520°C x 6h + water quenching) to obtain Al-10Ni-15Si alloy subjected to heat treatment + Sr / Sm / P modification.

[0120] The microstructural characteristics of the alloy prepared in this example were observed and analyzed. Figure 6The optical microstructure of the Al-10Ni-15Si alloy modified by Sr / Sm / P in the heat treatment state in Example 3. Compared with the alloy prepared in Comparative Example 1, the coarse primary Si, the long strip-shaped eutectic Si phase, and the primary and eutectic Al3Ni phases in the alloy modified by composite modification + heat treatment are significantly refined.

[0121] The XRD pattern of the alloy in this example is as follows: Fig. 9 shown.

[0122] The test results show that the thermal conductivity of the alloy in this embodiment is 205.5 W / (m·K), the tensile strength is 188 MPa, the elongation is 6.0%, and the thermal expansion coefficient is 14.0×10 -6 K -1 (@100℃). Compared with the alloy prepared in Comparative Example 1, the comprehensive performance of the alloy prepared in this embodiment is significantly improved, with thermal conductivity increased by 31.6%, elongation increased by 53.8%, and thermal expansion coefficient decreased by 2.1%. Sr / Sm / P modification and heat treatment effectively improve the microstructure morphology of the Al-10Ni-15Si alloy, and at the same time improve the thermal conductivity, mechanical and thermal expansion properties of the alloy.

[0123] Example 4: Preparation of Al-12Ni-13Si-0.1Sr-0.3Sm-0.3P alloy

[0124] The preparation process and raw materials for preparing the alloy in this embodiment are similar to those in Example 3, except that the components of the prepared alloy are different. The specific steps and process parameters are as follows:

[0125] (1) Alloy preparation: According to the target composition Al-12Ni-13Si-0.1Sr-0.3Sm-0.3P alloy, the raw materials of pure aluminum, Al-20Ni, Al-50Si, Al-20Sr, Al-20Sm and Cu-16P master alloy required to prepare the target alloy were calculated and weighed respectively;

[0126] (2) Alloy smelting: The weighed raw materials are melted in a furnace at a melting temperature of 820°C. After all the raw materials are melted, they are stirred for 2 minutes to make the composition uniform, and then allowed to stand and heat for 5 minutes to obtain the desired Al-Ni-Si alloy melt.

[0127] (3) Adding microalloying elements Sr / Sm: Add Al-10Sr and Al-20Sm master alloys to the Al-Ni-Si alloy melt. After the master alloy is completely melted, stir for 2 minutes to make the composition uniform, and keep it at room temperature for 5 minutes to obtain the aluminum alloy melt after microalloying modification.

[0128] (4) P modification treatment: adding Cu-16P master alloy to the aluminum alloy melt in step (3) for modification treatment, maintaining the temperature at 800° C., stirring for 2 min after the Cu-P master alloy is completely melted to make the composition uniform, and standing and keeping the temperature for 5 min to obtain the aluminum alloy melt after P modification treatment;

[0129] (5) Melt refining and slag removal: remove slag from the surface of the alloy melt after melting in step (4), mix the commercially available YT-J-1 refining agent and YT-D-4 slag removal agent in a ratio of 1:1, add the mixture to the alloy melt by nitrogen blowing to perform refining and slag removal, and leave the mixture to stand and keep warm for 10 minutes;

[0130] (6) melt casting: the melt in step (5) was cooled to 740°C, kept at this temperature for 5 minutes, and then cast into a metal mold preheated to 200°C. The size of the casting was 100 mm × 45 mm × 15 mm. The casting was naturally cooled and solidified to obtain a hypereutectic Al-12Ni-13Si alloy casting modified by Sr / Sm / P. Samples were taken from the casting for analysis.

[0131] (7) Heat treatment of Al-Ni-Si based alloy castings: The castings obtained in step (6) are subjected to solution treatment (520°C x 6h + water quenching) to obtain heat treated Sr / Sm / P modified Al-12Ni-13Si alloy.

[0132] The microstructural characteristics of the alloy prepared in this example were observed and analyzed. Figure 7 This is an optical microstructure of the Al-10Ni-15Si alloy modified by Sr / Sm / P in the heat treatment state in Example 4. Compared with the alloy prepared in Comparative Example 2, in the alloy modified by composite modification + heat treatment, the coarse primary Si, the long strip-shaped eutectic Si phase, and the primary and eutectic Al3Ni phases are all significantly refined.

[0133] The test results show that the alloy has a thermal conductivity of 213 W / (m·K), a tensile strength of 177 MPa, an elongation of 6.5%, and a thermal expansion coefficient of 14.6×10 -6 K -1 (@100°C). Compared with the alloy prepared in Comparative Example 2, the comprehensive performance of the alloy prepared in this embodiment is significantly improved, with thermal conductivity increased by 32.2%, elongation increased by 58.5%, and thermal expansion coefficient decreased by 1.4%. Sr / Sm / P modification and heat treatment effectively improve the microstructure morphology of the Al-12Ni-13Si alloy, and at the same time improve the thermal conductivity, mechanical and thermal expansion properties of the alloy.

[0134] Example 5: Preparation of Al-10Ni-10Si-0.1Sr-0.3Sm-0.3P alloy

[0135] The preparation process and raw materials for preparing the alloy in this embodiment are similar to those in Example 3, except that the components of the prepared alloy are different. The specific steps and process parameters are as follows:

[0136] (1) Alloy preparation: According to the target composition Al-10Ni-10Si-0.1Sr-0.3Sm-0.3P alloy, the raw materials of pure aluminum, Al-20Ni, Al-50Si, Al-20Sr, Al-20Sm and CuP master alloy required to prepare the target alloy are calculated and weighed respectively;

[0137] (2) Alloy smelting: The weighed raw materials are melted in a furnace at a melting temperature of 850°C. After all the raw materials are melted, they are stirred for 2 minutes to make the composition uniform. The raw materials are then allowed to stand and heat-insulated for 5 minutes to obtain the desired Al-Ni-Si alloy melt.

[0138] (3) Adding microalloying elements Sr / Sm: Add Al-20Sr and Al-20Sm master alloys to the Al-Ni-Si alloy melt. After the master alloy is completely melted, stir for 2 minutes to make the composition uniform, and keep it at room temperature for 5 minutes to obtain the aluminum alloy melt after microalloying modification.

[0139] (4) P modification treatment: adding CuP master alloy (Cu-16P) to the aluminum alloy melt in step (3) for modification treatment, maintaining the temperature at 800°C, stirring for 2 minutes after the Cu-P master alloy is completely melted to make its composition uniform, and keeping it at the temperature for 5 minutes to obtain an aluminum alloy melt after P modification treatment;

[0140] (5) Melt refining and slag removal: remove slag from the surface of the alloy melt after melting in step (4), mix the commercially available YT-J-1 refining agent and YT-D-4 slag removal agent in a ratio of 1:1, add the mixture to the alloy melt by nitrogen blowing to perform refining and slag removal, and leave the mixture to stand and keep warm for 10 minutes;

[0141] (6) melt casting: the melt in step (5) was cooled to 770°C, kept at this temperature for 5 minutes, and then cast into a metal mold preheated to 200°C. The size of the casting was 100 mm × 45 mm × 15 mm. The casting was naturally cooled and solidified to obtain a hypereutectic Al-10Ni-10Si alloy casting modified by Sr / Sm / P. Samples were taken from the casting for analysis.

[0142] (7) Heat treatment of Al-Ni-Si based alloy castings: The castings obtained in step (6) are subjected to solution treatment (520°C x 6h + water quenching) to obtain heat treated Sr / Sm / P modified Al-10Ni-10Si alloy.

[0143] The microstructural characteristics of the alloy prepared in this example were observed and analyzed. Figure 8 The optical microstructure of the Al-10Ni-10Si alloy modified by Sr / Sm / P heat treatment in Example 5. Compared with the alloy prepared in Comparative Example 3, the coarse primary Si, the long strip-shaped eutectic Si phase, and the primary and eutectic Al3Ni phases in the alloy modified by composite modification + heat treatment are significantly refined.

[0144] The test results show that the thermal conductivity of the alloy in this embodiment is 215.5 W / (m·K), the tensile strength is 171 MPa, the elongation is 7.1%, and the thermal expansion coefficient is 15.1×10 -6 K -1 (@100℃). Compared with the alloy prepared in comparative example 3, the comprehensive performance of the alloy prepared in this embodiment is significantly improved, with thermal conductivity increased by 29.0%, elongation increased by 61.4%, and thermal expansion coefficient decreased by 1.9%. Sr / Sm / P modification and heat treatment effectively improve the microstructure morphology of Al-10Ni-10Si alloy, and at the same time improve the thermal conductivity, mechanical and thermal expansion properties of the alloy.

[0145] In order to better compare and illustrate the differences in the processes and effects of each comparative example and the embodiment, the performance data are summarized in Table 1. The embodiment of the present invention prepares a hypereutectic alloy melt by ordinary metal mold casting, and regulates the structure and properties of the alloy by microalloying modification combined with heat treatment process. This process can significantly refine the structure of the alloy and simultaneously improve the thermal conductivity, mechanical and thermal expansion properties of the alloy. In particular, the comprehensive performance of Example 3 prepared based on Sm / Sr / P composite modification combined with heat treatment process is better. Compared with the Al-10Ni-15Si alloy prepared by ordinary metal mold casting in Comparative Example 1, it achieves the simultaneous improvement of the thermal conductivity, mechanical properties and thermal expansion properties of the hypereutectic Al-Ni-Si cast aluminum alloy while refining the structure.

[0146] Table 1 Properties of various alloys in comparative examples and embodiments

[0147]

[0148] Note: The improvement is calculated for the same target alloy under the same conditions.

[0149] The implementation methods of the present invention are not limited to the embodiments described, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A high thermal conductivity and low expansion Al-Ni-Si based alloy, characterized in that: Mainly composed of the following components by mass percentage composition: Ni 10~30% Si 10~30% Sr 0～1％ Sm 0~1% P 0.01～1％ The balance is Al; the contents of Sr and Sm are different and are 0; The high thermal conductivity and low expansion Al-Ni-Si based alloy is obtained by subjecting Al-Ni-Si alloy melt to microalloying and modification with Sr and / or Sm, and then modification with P; casting and solution treatment.

2. The high thermal conductivity and low expansion Al-Ni-Si based alloy according to claim 1, characterized in that: Ni 10~30% Si 10~30% Sr 0.01～1％ Sm 0.01~1% P 0.05～1％ The balance is Al.

3. The high thermal conductivity and low expansion Al-Ni-Si based alloy according to claim 2, characterized in that: Ni 10~20% Si 10~20% Sr 0.05～0.5％ Sm 0.1~1% P 0.05～0.5％ The balance is Al.

4. The high thermal conductivity and low expansion Al-Ni-Si based alloy according to claim 3, characterized in that: The content of Ni is 10 to 15%.

5. The method for preparing the high thermal conductivity and low expansion Al-Ni-Si based alloy according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Preparing an Al-Ni-Si alloy melt: melting pure aluminum, an aluminum-nickel master alloy, and an aluminum-silicon master alloy, mixing them, and standing them to keep them warm to obtain an Al-Ni-Si alloy melt; (2) subjecting the Al-Ni-Si alloy melt to a microalloying treatment of Sr and / or Sm, and then to a P modification treatment; (3) refining and removing slag from the modified aluminum alloy melt, and casting to obtain a casting; (4) subjecting the casting to a solution treatment to obtain an Al-Ni-Si based alloy with high thermal conductivity and low expansion; The microalloying modification treatment in step (2) is to add a master alloy containing Sr and / or Sm into an Al-Ni-Si alloy melt to obtain a microalloyed aluminum alloy melt; The P modification treatment in step (2) refers to adding a P-containing master alloy to the melt for modification treatment; The solution treatment in step (4) refers to heat treatment at 500-540° C. for 6-8 hours and water quenching.

6. The method for preparing the high thermal conductivity and low expansion Al-Ni-Si based alloy according to claim 5, characterized in that: The P-containing master alloy is a Cu-16P master alloy; The microalloying modification treatment in step (2) specifically refers to adding one or both of Al-Sr and Al-Sm master alloys into the Al-Ni-Si alloy melt, melting, mixing, and standing for 3 to 8 minutes to obtain an aluminum alloy melt modified by Sr / Sm alone or Sr and Sm in combination; The P modification treatment in step (2) specifically refers to mixing the P-containing master alloy evenly after it is completely melted, and keeping it at a temperature for 3 to 8 minutes to obtain an aluminum alloy melt after the P modification treatment.

7. The method for preparing the high thermal conductivity and low expansion Al-Ni-Si based alloy according to claim 6, characterized in that: The Al-Sr master alloy is an Al-20Sr alloy; the Al-Sm master alloy is an Al-20Sm alloy; before adding the Al-Sr and Al-Sm master alloys into the Al-Ni-Si alloy melt, the scum on the surface of the Al-Ni-Si alloy melt is removed.

8. The method for preparing the high thermal conductivity and low expansion Al-Ni-Si based alloy according to claim 5, characterized in that: In step (1), the aluminum-nickel master alloy is Al-20Ni; the aluminum-silicon master alloy is Al-50Si; The melting temperature in step (1) is 750-900° C.; the mixing is stirring; and the stirring time is 1-2 min. The time for standing and keeping warm is 5 to 20 minutes.

9. The method for preparing the high thermal conductivity and low expansion Al-Ni-Si based alloy according to claim 5, characterized in that: The refining and slag removal in step (3) refers to adding a refining agent and a slag removal agent, refining and slag removal, and then standing and keeping warm; The casting molding refers to molding by casting; before casting, the alloy melt is cooled by 30-80°C but the temperature of the melt is at or above the liquidus temperature; the out-of-furnace casting temperature is maintained at 700-850°C.

10. The use of the high thermal conductivity and low expansion Al-Ni-Si based alloy according to any one of claims 1 to 4, characterized in that: The high thermal conductivity and low expansion Al-Ni-Si based alloy is used for electronic devices and heat dissipation devices.

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