High-toughness high-thermal-conductivity high-temperature-resistant aluminum alloy and preparation method thereof

Abstract

The invention discloses a high-strength and high-toughness high-thermal-conductivity high-temperature-resistant aluminum alloy and a preparation method thereof. The high-strength and high-toughness high-thermal-conductivity high-temperature-resistant aluminum alloy is composed of the following components in percentage by weight: 6-12% of Si; 1-3% of Ni; 1-4% of Fe; 0 to 3 percent of Mn; the sum of all the components is 100%. The preparation method comprises the steps of cast ingot preparation, gas atomization powder preparation, blank preparation and hot extrusion. According to the alloy, uniformly dispersed fine granular IMC is obtained through a powder metallurgy method, and due to the high volume fraction and the fine microstructure of the IMC, the alloy has excellent room-temperature and high-temperature mechanical and heat-conducting properties. The room-temperature tensile strength of the alloy is 341-409 MPa, the ductility is 14.5-15.6%, the high-temperature tensile strength is 227-261 MPa after heat preservation is conducted for 30 min at the temperature of 300 DEG C, the heat conductivity at the room temperature is 146-151 W.m <-1 >. K <-1 >, and the requirements of modern industrial development are met.

Description

Technical Field

[0001] The present invention belongs to the field of aluminum alloy materials and processing, and specifically relates to a high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy and a preparation method thereof. Background Art

[0002] Aluminum alloys are widely used in aerospace, automobile, electronic equipment and other fields due to their light weight, high strength and good processing performance. However, parts working in high temperature environments, such as automobile engine cylinders, pistons, aircraft engine turbine blades, etc., usually have working environment temperatures above 300°C, which places extremely high demands on the thermal conductivity and high temperature resistance of the materials.

[0003] At present, the most widely used high-temperature resistant alloys are mainly Al-Cu alloys, but they usually need to be precipitated through low-temperature aging treatment. 2 Cu phase is used to strengthen the alloy. However, when the service temperature exceeds 200°C, these nanoscale precipitation phases will coarsen rapidly, resulting in a decrease in the high-temperature mechanical properties of the alloy. In addition, a large amount of Cu elements exist in the form of solid solution atoms or precipitated phases, which reduces the thermal conductivity of the alloy, making it difficult for the alloy to simultaneously have the characteristics of high strength, toughness, high thermal conductivity and high temperature resistance. The Al-Si alloys have the characteristics of good volume stability of the second phase, small thermal expansion coefficient and good thermal conductivity. However, the traditional Al-Si alloy eutectic structure is coarse and lacks corresponding binary precipitation phases and dispersed phases, which makes it difficult to achieve sufficient high-temperature strengthening effect.

[0004] In order to solve this problem, researchers added Fe, Ni and other elements with low diffusion rate and low solubility to Al-Si alloys to form interconnected intermetallic compounds (IMC) with high thermal stability, improve the high temperature strength of the alloy, and ensure the thermal conductivity of the alloy. Although the Al-Si-Ni-Fe-Mn alloy formed by high pressure die casting has good high temperature resistance, it cannot avoid the formation of coarse IMC, which reduces the plasticity of the alloy (MSEA 872 (2023) 144977.). DR Manca et al. prepared Al-Si-Ni-Fe alloy by selective laser cladding. Although it has excellent thermal stability, it has obvious defects and the fine IMC is unevenly distributed (Materials Letters 236 (2019) 676-679.). In addition, the cost of selective laser cladding technology is high and cannot meet the needs of large-scale production.

[0005] Therefore, it is necessary to use certain economical process technologies, combined with the high volume fraction and thermally stable second phase in Al-Si-Ni-Fe alloy, to prepare a fine-structured, uniform, high thermal conductivity, and heat-resistant aluminum alloy, to solve the problem that aluminum alloys are difficult to simultaneously have high strength, high thermal conductivity, and high temperature resistance, and to broaden the application of aluminum alloys. Summary of the invention

[0006] In view of this, the purpose of the present invention is to overcome the shortcomings of the prior art, and to provide a high-strength, high-toughness, high-heat-conductivity, high-temperature-resistant aluminum alloy and its preparation method by adjusting and optimizing the aluminum alloy composition and its powder metallurgy process. The alloy obtains uniformly dispersed fine-grained IMC through a powder metallurgy method. Due to the high volume fraction and fine microstructure of IMC, it has excellent mechanical and thermal conductivity at room temperature and high temperature. The room temperature tensile strength of the alloy is 341-409MPa, the elongation is 14.5-15.6%, the high-temperature tensile strength after being kept at 300℃ for 30min is 227-261MPa, the elongation is 19.6-22.6%, and the thermal conductivity at room temperature is 146-

[0007] 151W·m -1 ·K -1 , to meet the needs of modern industrial development.

[0008] The present invention provides a high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy, which is composed of the following components by weight percentage:

[0009] Si: 6-12%;

[0010] Ni: 1~3%;

[0011] Fe: 1~4%;

[0012] Mn: 0~3%;

[0013] The balance is Al, and the sum of the components is 100%.

[0014] The alloy has a fine and uniform structure and is an intermetallic compound (IMC) containing Fe and Ni with high thermal stability. The room temperature tensile strength of the alloy is 341-409 MPa, the elongation is 14.5-15.6%, the high temperature tensile strength after being kept at 300°C for 30 minutes is 227-261 MPa, the elongation is 19.6-22.6%, and the thermal conductivity at room temperature is 146-151 W·m -1 ·K -1 .

[0015] Preferably, the content of element Si in the alloy is 6-9%.

[0016] Preferably, the content of element Ni in the alloy is 1.2-2.4%.

[0017] Preferably, the content of element Fe in the alloy is 2-3%.

[0018] Preferably, the content of Mn element in the alloy is 1-2%.

[0019] The balance is Al, and the sum of the components is 100%.

[0020] The invention provides a method for preparing a high-strength, high-toughness, high-thermal-conductivity and high-temperature-resistant aluminum alloy, which comprises ingot preparation, gas atomization powder making, blank making and hot extrusion.

[0021] The ingot preparation comprises the following steps and process conditions:

[0022] (1) Original pure Al (≥99.8%), Al-20Si master alloy, Al-10Ni master alloy, Al-20Fe master alloy, Al-10Mn master alloy are prepared according to the weight percentage of Si: 6-12%, Ni: 1-3%, Fe: 1-4%, Mn: 0-3%, and the rest is Al.

[0023] (2) The raw materials are placed in a smelting furnace for smelting at a temperature of 700 to 750° C. The smelting times are 2 to 4 times to obtain an Al-Si-Ni-Fe-Mn alloy ingot with uniform composition.

[0024] The aerosol powder making process comprises the following steps and process conditions:

[0025] (1) placing an Al-Si-Ni-Fe-Mn alloy ingot into a gas atomization furnace and atomizing the ingot using high-purity argon gas, wherein the pressure of the argon gas is 3-6 MPa and the superheat value of the molten metal is in the range of 100°C to 300°C;

[0026] (2) The atomized spherical Al-Si-Ni-Fe-Mn alloy powder is sieved to obtain three types of particles: <16 μm, 16-53 μm, and >53 μm.

[0027] The blank making process comprises the following steps and process conditions:

[0028] The powder is placed in a 6061 aluminum alloy sheath and cold pressed at a molding pressure of 200 to 400 MPa for 5 to 10 seconds to form a blank sample.

[0029] The hot extrusion comprises the following steps and process conditions:

[0030] (1) Place the blank sample in a resistance furnace for insulation at a temperature of 300-450°C for 30-45 minutes; place the extrusion nozzle in a resistance furnace for insulation at a temperature of 350-500°C for 30-60 minutes; the extrusion die temperature is 350-500°C;

[0031] (2) Place the extrusion nozzle after the heat preservation into the extrusion die, put the sample in for hot extrusion, and the extrusion ratio is 12 to 30, and then air cool to room temperature.

[0032] Preferably, the aluminum alloy powder metallurgy process of the present invention comprises the following steps and process parameters:

[0033] Step 1: Ingot preparation

[0034] (1) Original pure Al (≥99.8%), Al-20Si master alloy, Al-10Ni master alloy, Al-20Fe master alloy, Al-10Mn master alloy are prepared according to the weight percentage of Si: 6-12%, Ni: 1-3%, Fe: 1-4%, Mn: 0-3%, and the rest is Al.

[0035] (2) placing the above raw materials into a smelting furnace for smelting at a temperature of 700 to 720° C. for 2 to 3 times to obtain an Al-Si-Ni-Fe-Mn alloy ingot with uniform composition;

[0036] Step 2: Atomization powder making

[0037] (1) placing an Al-Si-Ni-Fe-Mn alloy ingot into a gas atomization furnace and atomizing the ingot using high-purity argon gas, wherein the pressure of the argon gas is 4-5 MPa and the superheat value of the molten metal is in the range of 100°C to 200°C;

[0038] (2) Screening the gas-atomized spherical Al-Si-Ni-Fe-Mn alloy powder to obtain three types of particles: <16 μm, 16 to 53 μm, and >53 μm;

[0039] Step 3: Blank Making

[0040] The powder is placed in a 6061 aluminum alloy package and cold pressed at a molding pressure of 200 to 300 MPa for 5 to 8 seconds to form a blank sample.

[0041] Step 4: Hot Extrusion

[0042] (1) Place the blank sample in a resistance furnace for insulation at a temperature of 300-450°C for 30 min; place the extrusion nozzle in a resistance furnace for insulation at a temperature of 350-500°C for 40 min; the extrusion die temperature is 350-500°C;

[0043] (2) Place the extrusion nozzle after the heat preservation into the extrusion die, put the sample in for hot extrusion, and the extrusion ratio is 18 to 25, and then air cool to room temperature.

[0044] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0045] The present invention provides a high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy and its preparation method (by weight percentage, Si6.0-9.0%, Ni 1.2-2.4%, Fe 2.0-3.0%, Mn 1.0-2.0%, and the balance Al) and its powder metallurgy process. Compared with the traditional high-temperature-resistant cast aluminum alloy, the present invention can obtain a Fe- and Ni-containing intermetallic compound (IMC) with fine and uniform structure and high thermal stability by adding Fe and Ni elements and coordinating with the powder metallurgy process, and significantly improve the mechanical properties, thermal conductivity and high-temperature resistance of the alloy. At the same time, powder metallurgy is a near-net-shape forming technology with high material utilization rate, high production efficiency, and basically eliminates alloy defects. Taking Example 1 as an example, the test results of the sample of Example 1 show that its structure is dispersed fine particles, the room temperature tensile strength and elongation after fracture are 409MPa and 15.2% respectively, the 300℃ tensile strength and elongation after fracture are 261MPa and 22.1% respectively, and the thermal conductivity reaches 146W·m -1 ·K -1 . It further expanded the application areas of aluminum alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a scanning electron microscope image of the high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy described in Example 1;

[0047] Figure 2 This is a scanning electron microscope image of the high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy described in Example 2;

[0048] Figure 3 This is a scanning electron microscope image of the high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy described in Example 3;

[0049] Figure 4 This is a scanning electron microscope image of the high-strength, high-toughness, high-thermal conductivity and high-temperature resistant aluminum alloy described in Example 4. DETAILED DESCRIPTION

[0050] The specific implementation of the present invention is further described below with reference to examples.

[0051] Example 1

[0052] A high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy and a powder metallurgy process thereof include the following steps and process parameters:

[0053] Step 1: Ingot preparation

[0054] (1) Original pure Al (≥99.8%), Al-20Si master alloy, Al-10Ni master alloy, Al-20Fe master alloy, Al-10Mn master alloy are prepared according to the weight percentage of Si: 7.5%, Ni: 1.5%, Fe: 2.3%, Mn: 1.3%, and the rest is Al.

[0055] (2) placing the above raw materials into a smelting furnace for smelting at a temperature of 720° C. for 2 smelting times to obtain an Al-Si-Ni-Fe-Mn alloy ingot with uniform composition;

[0056] Step 2: Atomization powder making

[0057] (1) placing an Al-Si-Ni-Fe-Mn alloy ingot into a gas atomization furnace and atomizing it using high-purity argon gas at a pressure of 4 MPa and a superheat of the molten metal of 100°C;

[0058] (2) Screening the gas-atomized spherical Al-Si-Ni-Fe-Mn alloy powder to obtain three types of particles: <16 μm, 16 to 53 μm, and >53 μm;

[0059] Step 3: Blank Making

[0060] Powders with a particle size of 16 to 53 μm were placed in a 6061 aluminum alloy sheath and cold pressed at a molding pressure of 300 MPa for 5 seconds to form a blank sample.

[0061] Step 4: Hot Extrusion

[0062] (1) Place the blank sample in a resistance furnace for insulation at a temperature of 300°C for 30 minutes; place the extrusion nozzle in a resistance furnace for insulation at a temperature of 350°C for 40 minutes; the extrusion die temperature is 350°C;

[0063] (2) The extrusion nozzle after the heat preservation is placed into the extrusion die, and the sample is placed in the die for hot extrusion with an extrusion ratio of 25, followed by air cooling to room temperature.

[0064] Example 2

[0065] A high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy and a powder metallurgy process thereof include the following steps and process parameters:

[0066] Step 1: Ingot preparation

[0067] (1) Original pure Al (≥99.8%), Al-20Si master alloy, Al-10Ni master alloy, Al-20Fe master alloy, Al-10Mn master alloy are prepared according to the weight percentage of Si: 9%, Ni: 2%, Fe: 2.5%, Mn: 1%, and the rest is Al.

[0068] (2) placing the above raw materials into a smelting furnace for smelting at a temperature of 700° C. for 2 smelting times to obtain an Al-Si-Ni-Fe-Mn alloy ingot with uniform composition;

[0069] Step 2: Atomization powder making

[0070] (1) placing an Al-Si-Ni-Fe-Mn alloy ingot into a gas atomization furnace and atomizing it using high-purity argon gas at a pressure of 4.5 MPa and a superheat of the molten metal of 150°C;

[0071] (2) Screening the gas-atomized spherical Al-Si-Ni-Fe-Mn alloy powder to obtain three types of particles: <16 μm, 16 to 53 μm, and >53 μm;

[0072] Step 3: Blank Making

[0073] Powder with a particle size of less than 16 μm was placed in a 6061 aluminum alloy sheath and cold pressed at a molding pressure of 200 MPa for 7 seconds to form a blank sample.

[0074] Step 4: Hot Extrusion

[0075] (1) Place the blank sample in a resistance furnace for insulation at a temperature of 350°C for 30 min; place the extrusion nozzle in a resistance furnace for insulation at a temperature of 400°C for 40 min; the extrusion die temperature is 400°C;

[0076] (2) The extrusion nozzle after the heat preservation is placed into the extrusion die, and the sample is placed in the die for hot extrusion with an extrusion ratio of 18, followed by air cooling to room temperature.

[0077] Example 3

[0078] A high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy and a powder metallurgy process thereof include the following steps and process parameters:

[0079] Step 1: Ingot preparation

[0080] (1) Original pure Al (≥99.8%), Al-20Si master alloy, Al-10Ni master alloy, Al-20Fe master alloy, Al-10Mn master alloy are prepared according to the weight percentage of Si: 8.5%, Ni: 2.3%, Fe: 2.1%, Mn: 1.5%, and the rest is Al.

[0081] (2) placing the above raw materials into a smelting furnace for smelting at a temperature of 710° C. for 3 times to obtain an Al-Si-Ni-Fe-Mn alloy ingot with uniform composition;

[0082] Step 2: Atomization powder making

[0083] (1) placing an Al-Si-Ni-Fe-Mn alloy ingot into a gas atomization furnace and atomizing it using high-purity argon gas at a pressure of 5 MPa and a superheat of the molten metal of 200°C;

[0084] (2) Screening the gas-atomized spherical Al-Si-Ni-Fe-Mn alloy powder to obtain three types of particles: <16 μm, 16 to 53 μm, and >53 μm;

[0085] Step 3: Blank Making

[0086] Powder with a particle size of more than 53 μm was placed in a 6061 aluminum alloy sheath and cold pressed at a molding pressure of 300 MPa for 6 seconds to form a blank sample.

[0087] Step 4: Hot Extrusion

[0088] (1) Place the blank sample in a resistance furnace for insulation at a temperature of 400°C for 30 min; place the extrusion nozzle in a resistance furnace for insulation at a temperature of 450°C for 40 min; the extrusion die temperature is 450°C;

[0089] (2) The extrusion nozzle after the heat preservation is placed into the extrusion die, and the sample is placed in the die for hot extrusion with an extrusion ratio of 25, followed by air cooling to room temperature.

[0090] Example 4

[0091] A high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy and a powder metallurgy process thereof include the following steps and process parameters:

[0092] Step 1: Ingot preparation

[0093] (1) Original pure Al (≥99.8%), Al-20Si master alloy, Al-10Ni master alloy, Al-20Fe master alloy, Al-10Mn master alloy are prepared according to the weight percentage of Si: 6.5%, Ni: 1.2%, Fe: 3%, Mn: 1.8%, and the rest is Al.

[0094] (2) placing the above raw materials into a smelting furnace for smelting at a temperature of 720° C. for 3 times to obtain an Al-Si-Ni-Fe-Mn alloy ingot with uniform composition;

[0095] Step 2: Atomization powder making

[0096] (1) placing an Al-Si-Ni-Fe-Mn alloy ingot into a gas atomization furnace and atomizing it using high-purity argon gas at a pressure of 4 MPa and a superheat of the molten metal of 100°C;

[0097] (2) Screening the gas-atomized spherical Al-Si-Ni-Fe-Mn alloy powder to obtain three types of particles: <16 μm, 16 to 53 μm, and >53 μm;

[0098] Step 3: Blank Making

[0099] Powders with a particle size of 16 to 53 μm were placed in a 6061 aluminum alloy sheath and cold pressed at a molding pressure of 200 MPa for 5 seconds to form a blank sample.

[0100] Step 4: Hot Extrusion

[0101] (1) Place the blank sample in a resistance furnace for insulation at a temperature of 450°C for 30 min; place the extrusion nozzle in a resistance furnace for insulation at a temperature of 500°C for 40 min; the extrusion die temperature is 500°C;

[0102] (2) The extrusion nozzle after the heat preservation is placed into the extrusion die, and the sample is placed in the die for hot extrusion with an extrusion ratio of 22, followed by air cooling to room temperature.

[0103] Figure 1-4 The scanning electron microscope images of four embodiments are illustrated. The alloy structure is composed of a dispersed granular heat-resistant second phase. The room temperature and high temperature mechanical properties and thermal conductivity of the powder metallurgy aluminum alloy of the above embodiments are measured. The results are shown in the following table. It can be seen from the table that the room temperature tensile strength of embodiments 1-4 is all above 341MPa, with the highest reaching 409MPa, and the elongation is all above 14%. And at 300℃, the tensile strength of the alloy is all above 227MPa, with the highest reaching 261MPa. In addition, the thermal conductivity of the alloy at room temperature is all 146W·m -1 ·K -1 The test results of the above embodiments show that the alloy of the present invention has the characteristics of high strength, high toughness, high thermal conductivity and high temperature resistance, and its comprehensive performance is greatly improved compared with ordinary aluminum alloys.

[0104]

[0105] The powder metallurgy aluminum alloy material of the present invention has significantly improved various mechanical properties while ensuring its high thermal conductivity, thereby expanding the application range of the powder metallurgy aluminum alloy material.

Claims

1. A high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy, characterized in that: The following components are used in percentage by weight Composition: Si: 6-12%; Ni: 1-3%; Fe: 1-4%; Mn: 0-3%; the balance is Al, the sum of each component is 100%; The alloy has a fine and uniform structure and is an intermetallic compound (IMC) containing Fe and Ni with high thermal stability. The room temperature tensile strength of the alloy is 341-409 MPa, the elongation is 14.5-15.6%, the high temperature tensile strength after being kept at 300°C for 30 minutes is 227-261 MPa, the elongation is 19.6-22.6%, and the thermal conductivity at room temperature is 146-151 W·m -1 ·K -1 .

2. The high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy according to claim 1, characterized in that: The content of element Si in the alloy is 6-9%.

3. The high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy according to claim 1, characterized in that: The content of Ni element in the alloy is 1.2-2.4%.

4. The high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy according to claim 1, characterized in that: The content of Fe element in the alloy is 2-3%.

5. The high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy according to claim 1, characterized in that: The content of Mn element in the alloy is 1-2%.

6. The method for preparing the high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy according to any one of claims 1 to 5, characterized in that: It includes ingot preparation, gas atomization powder making, billet making and hot extrusion.

7. The method for preparing the high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy according to claim 6, characterized in that: The ingot preparation comprises the following steps: (1) preparing the original pure Al, Al-20Si master alloy, Al-10Ni master alloy, Al-20Fe master alloy and Al-10Mn master alloy according to the weight percentage of Si: 6-12%, Ni: 1-3%, Fe: 1-4%, Mn: 0-3%, and the rest Al; (2) The raw materials are placed in a smelting furnace for smelting at a temperature of 700 to 750° C. The smelting times are 2 to 4 times to obtain an Al-Si-Ni-Fe-Mn alloy ingot with uniform composition.

8. The method for preparing the high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy according to claim 6, characterized in that: The aerosol powder making comprises the following steps: (1) placing an Al-Si-Ni-Fe-Mn alloy ingot into a gas atomization furnace and atomizing the ingot using high-purity argon gas, wherein the pressure of the argon gas is 3-6 MPa and the superheat value of the molten metal is in the range of 100°C to 300°C; (2) The atomized spherical Al-Si-Ni-Fe-Mn alloy powder is sieved to obtain three types of particles: <16 μm, 16-53 μm, and >53 μm.

9. The method for preparing the high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy according to claim 6, characterized in that: The blank making comprises the following steps: Powders of different particle sizes are placed in a 6061 aluminum alloy sheath and cold pressed at a molding pressure of 200 to 400 MPa for 5 to 10 seconds to form a blank sample.

10. The method for preparing the high-strength, high-toughness, high-thermal-conductivity, high-temperature-resistant aluminum alloy according to claim 6, characterized in that: The hot extrusion comprises the following steps: (1) Place the blank sample in a resistance furnace for insulation at a temperature of 300-450°C for 30-45 minutes; place the extrusion nozzle in a resistance furnace for insulation at a temperature of 350-500°C for 30-60 minutes; the extrusion die temperature is 350-500°C; (2) Place the extrusion nozzle after the heat preservation into the extrusion die, put the sample in for hot extrusion, and the extrusion ratio is 12 to 30, and then air cool to room temperature.

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