High-strength heat-resistant aluminum alloy as well as preparation method and application thereof

Abstract

The invention relates to a high-strength heat-resistant aluminum alloy as well as a preparation method and application thereof. The high-strength heat-resistant aluminum alloy comprises the following components in parts by weight: 4-6% of Ni; 0.5 to 1 percent of Ti; 0.5 to 1% of Zr; 0.1 to 0.5 percent of Si; 0.1 to 0.5 percent of Mg; 1-5% of Cu; 0.1 to 0.5 percent of Sc; and the balance of Al. Compared with the prior art, the obtained aluminum alloy is excellent in mechanical property, high in high temperature resistance and small in thermal expansion coefficient, and the mechanical property is slightly reduced when the aluminum alloy works at high temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a high-strength heat-resistant aluminum alloy and a preparation method and application thereof. Background Art

[0002] Aluminum alloy is a material obtained by adding other alloying elements to aluminum. Usually, copper (Cu), silicon (Si), magnesium (Mg), manganese (Mn), zinc (Zn) and other elements are added to aluminum alloy. In addition, chromium (Cr), silver (Ag), iron (Fe), boron (B), nickel (Ni) and other elements are also added. Adding these alloying elements to aluminum alloy can significantly improve its comprehensive performance while maintaining the characteristics of pure aluminum, thus making aluminum alloy widely used. Since the 21st century, elements such as zirconium (Zr), titanium (Ti) and scandium (Sc) [1] have also been widely welcomed by researchers. Adding them to aluminum alloy in trace amounts can produce a new generation of aluminum alloy materials, which can improve the comprehensive performance of aluminum alloy to meet the increasingly high requirements of aluminum alloy in various fields.

[0003] Among aluminum alloys used in automobiles, cast aluminum alloys account for up to 80%. Cast aluminum alloys have good fluidity and filling capacity, and moderate mechanical properties. They are widely used to replace cast iron materials to manufacture engine parts, cylinder heads, wheels, bumpers and other structural parts. More and more engine pistons are made of aluminum alloys. In the engine, the working conditions of the piston are the worst. The instantaneous temperature of the high-temperature gas in the combustion chamber can reach 2000°C, and the maximum operating temperature of the top of the piston has exceeded 400°C. At the same time, it must withstand a gas pressure of 10-15MPa. At the same time, the piston has a complex structure and needs to move at high speed, so the material must be light in weight, have good casting formability and wear resistance, and have a small thermal expansion coefficient.

[0004] For example, CN111876637B discloses a heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy and a preparation method and application, which belongs to the field of cast aluminum alloy. The heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy includes the following elements in mass percentage: Si is 11.5-22%, Cu is 5.0-7.0%, Ni is 3.5-5.0%, Mg is 0.8-1.5%, Mn is 0.4-0.8%, Fe is 0.8-1.2%, Zr is 0.08-0.25%, Ti is 0.08-0.25%, V is 0.08-0.25%, Sr is 0.1-0.5%, and the remainder is Al and impurities, wherein the total impurity content is not more than 0.3%. The preparation method is: after the raw material is smelted, the raw material with Sr added is subjected to a modification treatment, and the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy is obtained by pressure casting from top to bottom.

[0005] For example, CN113388759B discloses a heat-resistant aluminum alloy powder and a preparation method thereof and an aluminum alloy molded part and a preparation method thereof, which belong to the technical field of aluminum alloys. The present invention provides a heat-resistant aluminum alloy powder, the chemical composition of which includes, by mass percentage, 3-15% Ni, 1.2-4% Fe, 0.2-1% Ti, 0.3-0.8% Sc, 0.4-3% Zr and the balance Al. The application adds Ni, Fe, Ti, Sc, and Zr elements to the aluminum alloy, which have a large diffusion solid solubility, a low equilibrium solid solubility, and a high-temperature diffusion coefficient in the aluminum matrix, and can ensure that the alloy forms a large number of fibrous Al3Ni, Al3Ti, Al3 (Sc, Zr) and granular Al9FeNi nano-precipitated phases, and the mechanical properties of the aluminum alloy under high temperature conditions are improved by synergistic enhancement of various morphological precipitation phases, precipitation strengthening, fine grain strengthening, and fiber load transfer.

[0006] However, the mechanical properties of the above aluminum alloy materials decrease by more than 50% when working at high temperatures, which is extremely dangerous when used in automobile pistons. Therefore, a high-strength and heat-resistant aluminum alloy is urgently needed. Summary of the invention

[0007] The purpose of the present invention is to provide a high-strength heat-resistant aluminum alloy and its preparation method and application in order to overcome the defects of the above-mentioned prior art. The aluminum alloy obtained in this application has excellent mechanical properties, strong high temperature resistance, small thermal expansion coefficient, and little decrease in mechanical properties when working at high temperatures.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] The present invention provides a high-strength heat-resistant aluminum alloy, comprising the following components in parts by weight:

[0010] Ni 4-6%; Ti 0.5-1%; Zr 0.5-1%; Si 0.1-0.5%; Mg 0.1-0.5%; Cu 1-5%; Sc0.1-0.5%; the balance is Al.

[0011] Preferably, the aluminum alloy comprises the following components in parts by weight:

[0012] Ni 4.5~5.5%; Ti 0.6-0.8%; Zr 0.5-0.7%; Si 0.1-0.4%; Mg 0.2-0.5%; Cu 3-5%; Sc 0.1-0.4%; the balance is Al.

[0013] The present invention also provides a method for preparing a high-strength heat-resistant aluminum alloy, comprising the following steps:

[0014] S1, weigh appropriate amounts of pure aluminum, pure copper, pure magnesium, Al-Si master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Ti master alloy, and Al-Ni master alloy according to the composition of the high-strength heat-resistant aluminum alloy for later use;

[0015] S2, adding the pure aluminum in S1 into a resistance furnace for alloy melting, adding the remaining components in S1 after Al is completely melted, stirring, and then refining and degassing while stirring continuously, and obtaining an alloy ingot after slag removal and casting;

[0016] S3, then heat-treating the alloy ingot in a muffle furnace, and then hot-rolling the alloy ingot after cooling to obtain an alloy hot-rolled plate, and then performing solid solution treatment and room temperature water quenching on the alloy hot-rolled plate to obtain a high-strength heat-resistant aluminum alloy.

[0017] Preferably, in step S1, the elements added are calculated by weight as follows:

[0018] Ni 4-6%; Ti 0.5-1%; Zr 0.5-1%; Si 0.1-0.5%; Mg 0.1-0.5%; Cu 1-5%; Sc0.1-0.5%; the balance is Al.

[0019] Preferably, in step S2, the alloy is smelted at a temperature of 700-750°C;

[0020] and / or, in step S2, the refining time is 10-30 min;

[0021] And / or, in step S2, the obtained alloy ingot is 70 mm×25 mm×10 mm.

[0022] Preferably, in step S3, the specific conditions of the heat treatment are:

[0023] The heating rate is 5-10℃ / min, the temperature is raised to 400℃-500℃ and kept for 12-20h, and then cooled naturally.

[0024] Preferably, the specific conditions of the hot rolling are:

[0025] Keep warm at 500-600℃ for 1-3h and hot roll to 5mm. The rolling direction is the length direction of the plate and the pressing amount per single pass is 0.1-0.2mm.

[0026] Preferably, the specific conditions of the solution treatment are:

[0027] The temperature is 500-600°C and the time is 1-2h, preferably the temperature is 560°C and the time is 1h.

[0028] The present invention further provides a high-strength and heat-resistant aluminum alloy obtained by the above-mentioned preparation method of the high-strength and heat-resistant aluminum alloy.

[0029] The present invention further provides a use of the high-strength and heat-resistant aluminum alloy as described above in the preparation of a piston.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. Compared with the prior art, the present application adds Ni to the aluminum alloy to form an Al-Ni eutectic alloy. Compared with the Al-Si eutectic alloy, the Al-Ni alloy has higher hardness and good heat resistance, which is mainly because the addition of Ni to the aluminum alloy will form an Al3Ni eutectic phase. For example, the diffusion coefficient D of different alloy elements in the aluminum matrix can be calculated by the Arrhenius formula. In fact, the diffusion coefficient of the Ni element is about one order of magnitude lower, so as to form a precipitated phase with better thermal stability and improve the heat resistance of the alloy. In addition, Mg and Si elements are still added to the alloy, so that the diffusion coefficients of each element are stepped, and different eutectic phases in the formed aluminum alloy are adjacent to each other to increase the density of the alloy, reduce pore defects, etc., and improve the mechanical properties of the alloy.

[0032] 2. Compared with the prior art, the present invention adds X elements (X = Sc, Zr, Ti) to the aluminum alloy, which can form Al3X phase with L12 structure with the matrix. This phase can act as a heterogeneous nucleation point to reduce the grain size inside the sample and achieve the effect of fine grain strengthening. It can also exist as a thermally stable precipitation phase to achieve the effect of precipitation strengthening. It maintains the orientation relationship with the matrix for a long time in the temperature range of 250-400°C, pins the grain boundary, and on the one hand, hinders dislocation slip and causes dislocation accumulation, and on the other hand, inhibits grain boundary movement and improves the resistance to plastic deformation. In addition, the addition of Sc will refine the matrix structure of the aluminum alloy, produce fine β-Sc phase distributed along the grain boundary, and preferentially combine with Mg to form Mg2Sc phase, reduce the formation of Mg2Si phase, promote the formation of Al-Mg, Al-Si, Al-Ni eutectics, increase the density of the alloy, reduce pore defects, and improve the mechanical properties of the alloy.

[0033] 3. Compared with the prior art, the conventional homogenization heat treatment and hot rolling of the present application improve the mechanical properties of aluminum alloys. After heat treatment, the alloy component segregation can be effectively removed, making the alloy component more homogenized. In fact, due to the addition of the element Sc, the α-Al, β-Sc and Mg2Sc phases will be significantly coarsened. The present application uses a muffle furnace for homogenization heat treatment to reduce the number of coarse phases, thereby significantly improving the segregation of alloy elements near dendrites. In addition, hot rolling can promote the dissolution of coarse phases and the precipitation of nano-scale precipitation phases. Due to the formation of Al-Mg, Al-Si, and Al-Ni eutectics, the present application forms coarse phases near adjacent grain boundaries. The use of hot rolling can effectively eliminate coarse phases near multiple grain boundaries, resulting in significant crack healing and elimination of Al-Mg, Al-Si, and Al-Ni eutectic grain boundary casting defects. DETAILED DESCRIPTION

[0034] For ease of understanding of the present application, the present application will be described more fully below by way of embodiments. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0035] For simplicity, this application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unclearly recorded range; and any lower limit can be combined with other lower limits to form an unclearly recorded range, and any upper limit can be combined with any other upper limit to form an unclearly recorded range. In addition, although not clearly recorded, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unclearly recorded range.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art in the technical field of the present application. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. It should be noted that, unless otherwise specified, the term "and / or" used herein includes any and all combinations of one or more related listed items, and "above" and "below" include the number, and the meaning of "multiple" in "one or more" is more than two.

[0037] In the engine, the working conditions of the piston are the worst. The instantaneous temperature of the high-temperature gas in the combustion chamber can reach 2000℃, and the maximum working temperature of the top of the piston has exceeded 400℃. At the same time, it has to withstand a gas pressure of 10-15MPa. At the same time, the piston has a complex structure and needs to move at high speed, so the material must have excellent mechanical properties, strong high temperature resistance, and a small thermal expansion coefficient. Aluminum alloy materials work at high temperatures, and how to make the mechanical properties meet the requirements is an urgent problem to be solved.

[0038] In a first aspect, an embodiment of the present application provides a high-strength heat-resistant aluminum alloy, comprising the following components in parts by weight:

[0039] Ni 4-6%; Ti 0.5-1%; Zr 0.5-1%; Si 0.1-0.5%; Mg 0.1-0.5%; Cu 1-5%; Sc0.1-0.5%; the balance is Al.

[0040] In an optional embodiment, the aluminum alloy includes the following components in parts by weight:

[0041] Ni 4.5~5.5%; Ti 0.6-0.8%; Zr 0.5-0.7%; Si 0.1-0.4%; Mg 0.2-0.5%; Cu 3-5%; Sc 0.1-0.4%; the balance is Al.

[0042] In an optional embodiment, the aluminum alloy includes the following components in parts by weight:

[0043] Ni 4.8%; Ti 0.65%; Zr 0.58%; Si 0.3%; Mg 0.3%; Cu 4%; Sc 0.3%; the balance is Al.

[0044] In the present application, Ni is added to the aluminum alloy to form an Al-Ni eutectic alloy. Compared with the Al-Si eutectic alloy, the Al-Ni alloy has higher hardness and good heat resistance, which is mainly because the addition of Ni to the aluminum alloy will form an Al3Ni eutectic phase. For example, the diffusion coefficient D of different alloying elements in the aluminum matrix can be calculated by the Arrhenius formula. In fact, the diffusion coefficient of the Ni element is about one order of magnitude lower, so as to form a precipitated phase with better thermal stability and improve the heat resistance of the alloy. In addition, Mg and Si elements are still added to the alloy, so that the diffusion coefficients of each element are stepped, and different eutectic phases in the formed aluminum alloy are adjacent to each other to increase the density of the alloy, reduce pore defects, etc., and improve the mechanical properties of the alloy.

[0045] Moreover, the present application adds X elements (X = Sc, Zr, Ti) to the aluminum alloy, which can form Al3X phase with L12 structure with the matrix. This phase can act as a heterogeneous nucleation particle, reduce the grain size inside the sample, and achieve the effect of fine grain strengthening. It can also exist as a thermally stable precipitation phase to achieve the effect of precipitation strengthening, maintain the orientation relationship with the matrix for a long time in the temperature range of 250-400 ° C, pin the grain boundary, on the one hand hinder the dislocation slip, resulting in dislocation accumulation, and on the other hand inhibit the grain boundary movement, and improve the resistance to plastic deformation. In addition, the addition of Sc will refine the matrix structure of the aluminum alloy, produce a fine β-Sc phase distributed along the grain boundary, and preferentially combine with Mg to form a Mg2Sc phase, reduce the formation of the Mg2Si phase, promote the formation of Al-Mg, Al-Si, Al-Ni eutectics, increase the density of the alloy, reduce pore defects, and improve the mechanical properties of the alloy.

[0046] In a second aspect, the present application provides a method for preparing a high-strength heat-resistant aluminum alloy, comprising the following steps:

[0047] S1, weigh appropriate amounts of pure aluminum, pure copper, pure magnesium, Al-Si master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Ti master alloy, and Al-Ni master alloy according to the composition of the high-strength heat-resistant aluminum alloy for later use;

[0048] S2, adding the pure aluminum in S1 into a resistance furnace for alloy melting, adding the remaining components in S1 after Al is completely melted, stirring, and then refining and degassing while stirring continuously, and obtaining an alloy ingot after slag removal and casting;

[0049] S3, then heat-treating the alloy ingot in a muffle furnace, and then hot-rolling the alloy ingot after cooling to obtain an alloy hot-rolled plate, and then performing solid solution treatment and room temperature water quenching on the alloy hot-rolled plate to obtain a high-strength heat-resistant aluminum alloy.

[0050] In an optional embodiment, in step S1, the elements added are calculated by weight as follows:

[0051] Ni 4-6%; Ti 0.5-1%; Zr 0.5-1%; Si 0.1-0.5%; Mg 0.1-0.5%; Cu 1-5%; Sc0.1-0.5%; the balance is Al.

[0052] In an optional embodiment, in step S1, the elements added are calculated by weight as follows:

[0053] Ni 4.5~5.5%; Ti 0.6-0.8%; Zr 0.5-0.7%; Si 0.1-0.4%; Mg 0.2-0.5%; Cu 3-5%; Sc 0.1-0.4%; the balance is Al.

[0054] In an optional embodiment, in step S1, the elements added are calculated by weight as follows:

[0055] Ni 4.8%; Ti 0.65%; Zr 0.58%; Si 0.3%; Mg 0.3%; Cu 4%; Sc 0.3%; the balance is Al.

[0056] In an optional embodiment, in step S2, the alloy is smelted at a temperature of 700-750°C, preferably 700°C.

[0057] In an optional embodiment, in step S2, the refining time is 10-30 min, preferably 20 min.

[0058] In an optional embodiment, in step S2, the obtained alloy ingot is 70 mm×25 mm×10 mm, that is, 70 mm in length, 25 mm in width, and 10 mm in thickness.

[0059] In an optional embodiment, in step S3, the specific conditions of the heat treatment are:

[0060] The heating rate is 5-10°C / min, preferably 5°C / min, the temperature is raised to 400°C-500°C and kept for 12-20h, preferably raised to 450°C and kept for 15h, and then cooled naturally.

[0061] After heat treatment, the segregation of alloy components can be effectively removed, making the alloy components more uniform. In fact, due to the addition of element Sc, the α-Al, β-Sc and Mg2Sc phases will be significantly coarsened. The present application uses a muffle furnace for homogenization heat treatment to reduce the number of coarse phases, thereby significantly improving the segregation of alloy elements near the dendrites.

[0062] In an optional embodiment, the specific conditions of the hot rolling are:

[0063] Keep the temperature at 500-600℃ for 1-3h, preferably keep the temperature at 560℃ for 2h, and hot roll to 5mm, the rolling direction is the length direction of the plate, the pressing amount in a single pass is 0.1-0.2mm, preferably 0.15mm.

[0064] Hot rolling can promote the dissolution of coarse phases and the precipitation of nano-scale precipitated phases. In this application, due to the formation of Al-Mg, Al-Si, and Al-Ni eutectics, coarse phases are formed near adjacent grain boundaries. Hot rolling can effectively eliminate coarse phases near multiple grain boundaries, resulting in significant crack healing and elimination of Al-Mg, Al-Si, and Al-Ni eutectic grain boundary casting defects.

[0065] In an optional embodiment, the specific conditions of the solution treatment are:

[0066] The temperature is 500-600°C and the time is 1-2h, preferably the temperature is 560°C and the time is 1h.

[0067] In a third aspect, an embodiment of the present application provides a high-strength and heat-resistant aluminum alloy obtained by the preparation method of the above-mentioned high-strength and heat-resistant aluminum alloy.

[0068] The above implementation is described in more detail below in conjunction with specific examples.

[0069] Example 1

[0070] This embodiment provides a high-strength heat-resistant aluminum alloy, and the preparation method thereof is as follows:

[0071] S1, according to the composition of high-strength heat-resistant aluminum alloy, weigh appropriate amounts of pure aluminum, pure copper, pure magnesium, Al-Si master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Ti master alloy, and Al-Ni master alloy for use, wherein the added elements are calculated by weight as follows: Ni 4.8%; Ti 0.65%; Zr 0.58%; Si 0.3%; Mg 0.3%; Cu 4%; Sc 0.3%; the balance is Al;

[0072] S2, add the pure aluminum in S1 into the resistance furnace for alloy melting, the melting temperature is 700℃, add the remaining components in S1 after Al is completely melted, stir, then perform refining and degassing while stirring continuously, the refining time is 20min, after slag removal and pouring, the alloy ingot is obtained, the alloy ingot is 70mm long, 25mm wide and 10mm thick;

[0073] S3, then heat-treating the alloy ingot in a muffle furnace at a heating rate of 5°C / min, heating to 450°C and keeping it for 15 hours, cooling naturally after heat treatment, and hot-rolling the alloy ingot after cooling, wherein, first, keeping it at 560°C for 2 hours, and hot-rolling it to 5 mm, the rolling direction is the length direction of the plate, and the single-pass pressing amount is 0.15 mm, to obtain an alloy hot-rolled plate, and then the alloy hot-rolled plate is subjected to 560°C / 1h solid solution treatment and room temperature water quenching to obtain a high-strength heat-resistant aluminum alloy.

[0074] Example 2

[0075] This embodiment provides a high-strength heat-resistant aluminum alloy, and the preparation method thereof is as follows:

[0076] S1, according to the composition of high-strength heat-resistant aluminum alloy, weigh appropriate amounts of pure aluminum, pure copper, pure magnesium, Al-Si master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Ti master alloy, and Al-Ni master alloy for use, wherein the added elements are calculated by weight as follows: Ni 4.5%; Ti 0.65%; Zr 0.58%; Si 0.3%; Mg 0.3%; Cu 4%; Sc 0.3%; the balance is Al;

[0077] S2, add the pure aluminum in S1 into the resistance furnace for alloy melting, the melting temperature is 700℃, add the remaining components in S1 after Al is completely melted, stir, then perform refining and degassing while stirring continuously, the refining time is 20min, after slag removal and pouring, the alloy ingot is obtained, the alloy ingot is 70mm long, 25mm wide and 10mm thick;

[0078] S3, then heat-treating the alloy ingot in a muffle furnace at a heating rate of 5°C / min, heating to 450°C and keeping it for 15 hours, cooling naturally after heat treatment, and hot-rolling the alloy ingot after cooling, wherein, first, keeping it at 560°C for 2 hours, and hot-rolling it to 5 mm, the rolling direction is the length direction of the plate, and the single-pass pressing amount is 0.15 mm, to obtain an alloy hot-rolled plate, and then the alloy hot-rolled plate is subjected to 560°C / 1h solid solution treatment and room temperature water quenching to obtain a high-strength heat-resistant aluminum alloy.

[0079] Example 3

[0080] This embodiment provides a high-strength heat-resistant aluminum alloy, and the preparation method thereof is as follows:

[0081] S1, according to the composition of high-strength heat-resistant aluminum alloy, weigh appropriate amounts of pure aluminum, pure copper, pure magnesium, Al-Si master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Ti master alloy, and Al-Ni master alloy for use, wherein the added elements are calculated by weight as follows: Ni 4.8%; Ti 0.65%; Zr 0.58%; Si 0.3%; Mg 0.3%; Cu 4%; Sc 0.2%; the balance is Al;

[0082] S2, add the pure aluminum in S1 into the resistance furnace for alloy melting, the melting temperature is 700℃, add the remaining components in S1 after Al is completely melted, stir, then perform refining and degassing while stirring continuously, the refining time is 20min, after slag removal and pouring, the alloy ingot is obtained, the alloy ingot is 70mm long, 25mm wide and 10mm thick;

[0083] S3, then heat-treating the alloy ingot in a muffle furnace at a heating rate of 5°C / min, heating to 450°C and keeping it for 15 hours, cooling naturally after heat treatment, and then hot-rolling the alloy ingot after cooling, wherein, first, keeping it at 560°C for 2 hours, and hot-rolling it to 5 mm, the rolling direction is the length direction of the plate, and the single-pass pressing amount is 0.15 mm, to obtain an alloy hot-rolled plate, and then the alloy hot-rolled plate is subjected to 560°C / 1h solid solution treatment and room temperature water quenching to obtain a high-strength heat-resistant aluminum alloy.

[0084] Example 4

[0085] This embodiment provides a high-strength heat-resistant aluminum alloy, and the preparation method thereof is as follows:

[0086] S1, according to the composition of high-strength heat-resistant aluminum alloy, weigh appropriate amounts of pure aluminum, pure copper, pure magnesium, Al-Si master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Ti master alloy, and Al-Ni master alloy for use, wherein the added elements are calculated by weight as follows: Ni 4.8%; Ti 0.65%; Zr 0.58%; Si 0.3%; Mg 0.2%; Cu 4%; Sc 0.2%; the balance is Al;

[0087] S2, add the pure aluminum in S1 into the resistance furnace for alloy melting, the melting temperature is 700℃, add the remaining components in S1 after Al is completely melted, stir, then perform refining and degassing while stirring continuously, the refining time is 20min, after slag removal and pouring, the alloy ingot is obtained, the alloy ingot is 70mm long, 25mm wide and 10mm thick;

[0088] S3, then heat-treating the alloy ingot in a muffle furnace at a heating rate of 5°C / min, heating to 450°C and keeping it for 15 hours, cooling naturally after heat treatment, and then hot-rolling the alloy ingot after cooling, wherein, first, keeping it at 560°C for 2 hours, and hot-rolling it to 5 mm, the rolling direction is the length direction of the plate, and the single-pass pressing amount is 0.15 mm, to obtain an alloy hot-rolled plate, and then the alloy hot-rolled plate is subjected to 560°C / 1h solid solution treatment and room temperature water quenching to obtain a high-strength heat-resistant aluminum alloy.

[0089] Comparative Example 1

[0090] This comparative example provides a high-strength heat-resistant aluminum alloy, and its preparation method is as follows:

[0091] S1, according to the composition of high-strength heat-resistant aluminum alloy, weigh appropriate amounts of pure aluminum, pure copper, pure magnesium, Al-Si master alloy, Al-Zr master alloy, Al-Ti master alloy, and Al-Ni master alloy for use, wherein the added elements are calculated by weight as follows: Ni 4.8%; Ti 0.65%; Zr 0.58%; Si 0.3%; Mg 0.2%; Cu 4%; the balance is Al;

[0092] S2, add the pure aluminum in S1 into the resistance furnace for alloy melting, the melting temperature is 700℃, add the remaining components in S1 after Al is completely melted, stir, then perform refining and degassing while stirring continuously, the refining time is 20min, after slag removal and pouring, the alloy ingot is obtained, the alloy ingot is 70mm long, 25mm wide and 10mm thick;

[0093] S3, then heat-treating the alloy ingot in a muffle furnace at a heating rate of 5°C / min, heating to 450°C and keeping it for 15 hours, cooling naturally after heat treatment, and then hot-rolling the alloy ingot after cooling, wherein, first, keeping it at 560°C for 2 hours, and hot-rolling it to 5 mm, the rolling direction is the length direction of the plate, and the single-pass pressing amount is 0.15 mm, to obtain an alloy hot-rolled plate, and then the alloy hot-rolled plate is subjected to 560°C / 1h solid solution treatment and room temperature water quenching to obtain a high-strength heat-resistant aluminum alloy.

[0094] Comparative Example 2

[0095] This comparative example provides a high-strength heat-resistant aluminum alloy, and its preparation method is as follows:

[0096] S1, according to the composition of high-strength heat-resistant aluminum alloy, weigh appropriate amounts of pure aluminum, pure copper, pure magnesium, Al-Si master alloy, Al-Sc master alloy, Al-Zr master alloy, and Al-Ti master alloy for use, wherein the added elements are calculated by weight as follows: Ti 0.65%; Zr 0.58%; Si 0.3%; Mg 0.3%; Cu 4%; Sc 0.3%; the balance is Al;

[0097] S2, add the pure aluminum in S1 into the resistance furnace for alloy melting, the melting temperature is 700℃, add the remaining components in S1 after Al is completely melted, stir, then perform refining and degassing while stirring continuously, the refining time is 20min, after slag removal and pouring, the alloy ingot is obtained, the alloy ingot is 70mm long, 25mm wide and 10mm thick;

[0098] S3, then heat-treating the alloy ingot in a muffle furnace at a heating rate of 5°C / min, heating to 450°C and keeping it for 15 hours, cooling naturally after heat treatment, and hot-rolling the alloy ingot after cooling, wherein, first, keeping it at 560°C for 2 hours, and hot-rolling it to 5 mm, the rolling direction is the length direction of the plate, and the single-pass pressing amount is 0.15 mm, to obtain an alloy hot-rolled plate, and then the alloy hot-rolled plate is subjected to 560°C / 1h solid solution treatment and room temperature water quenching to obtain a high-strength heat-resistant aluminum alloy.

[0099] Comparative Example 3

[0100] This embodiment provides a high-strength heat-resistant aluminum alloy, and the preparation method thereof is as follows:

[0101] S1, according to the composition of high-strength heat-resistant aluminum alloy, weigh appropriate amounts of pure aluminum, pure copper, pure magnesium, Al-Si master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Ti master alloy, and Al-Ni master alloy for use, wherein the added elements are calculated by weight as follows: Ni 4.8%; Ti 0.65%; Zr 0.58%; Si 0.3%; Mg 0.3%; Cu 4%; Sc 0.3%; the balance is Al;

[0102] S2, add the pure aluminum in S1 into the resistance furnace for alloy melting, the melting temperature is 700℃, add the remaining components in S1 after Al is completely melted, stir, then perform refining and degassing while continuously stirring, the refining time is 20min, after slag removal and pouring, the alloy ingot is obtained, the alloy ingot is 70mm long, 25mm wide and 10mm thick.

[0103] Test Case

[0104] The mechanical properties of the aluminum alloys prepared in Examples 1, 2, 3, 4 and Comparative Examples 1, 2, 3 were tested at room temperature and 400° C. using a universal mechanical testing machine. The results are shown in Table 1.

[0105] Table 1

[0106]

[0107] It can be seen from Table 1 that the mechanical properties of the aluminum alloys of Examples 1 to 4 of the present application are better than those of Comparative Examples 1 to 3, indicating that the aluminum alloys obtained by the technical solution of the present application have excellent mechanical properties.

[0108] Furthermore, in Examples 1 to 4, the mechanical properties of the aluminum alloy do not decrease by more than 50% at high temperatures, indicating that the aluminum alloy obtained in the present application has excellent high temperature resistance, that is, high strength and high toughness at high temperatures. This is mainly because Ni is added to the aluminum alloy to form an Al-Ni eutectic alloy, and Mg and Si elements are still added to the alloy, so that the diffusion coefficients of each element are stepped, and different eutectic phases in the formed aluminum alloy are adjacent to increase the density of the alloy, reduce pore defects, etc., so that the mechanical properties of the alloy are significantly improved.

[0109] In particular, it can be seen from Example 1 and Comparative Example 1 that without adding Sc element, the mechanical properties of aluminum alloy have a significant decrease. This is mainly because the addition of Sc element can form Al3X phase with L12 type structure with the matrix. This phase can act as a heterogeneous nucleation particle to reduce the grain size inside the sample and achieve the effect of fine grain strengthening. It can also exist as a thermally stable precipitation phase to achieve the effect of precipitation strengthening. It maintains the orientation relationship with the matrix for a long time in the temperature range of 250-400°C, so that the high temperature resistance is significantly improved, and it can pin the grain boundary, on the one hand, hinder the dislocation slip, resulting in dislocation accumulation, and on the other hand, inhibit the grain boundary movement and improve the resistance to plastic deformation. In addition, the addition of Sc will refine the matrix structure of the aluminum alloy, produce a fine β-Sc phase distributed along the grain boundary, and preferentially combine with Mg to form a Mg2Sc phase, reduce the formation of the Mg2Si phase, promote the formation of Al-Mg, Al-Si, Al-Ni eutectics, increase the density of the alloy, reduce pore defects, and improve the mechanical properties of the alloy.

[0110] In particular, it can be seen from Example 1 and Comparative Example 2 that after the Ni element is not added, the types of Al-X (Mg, Si) formed are reduced, which reduces the density of the alloy and makes the coarse phase at the grain boundary tend to be uniform, which is not conducive to reducing pore defects and reduces the mechanical properties.

[0111] Moreover, without hot rolling and heat treatment, the mechanical properties of Example 3 decrease too much. Without heat treatment, the segregation of alloy components cannot be effectively removed. In fact, due to the addition of element Sc, the α-Al, β-Sc and Mg2Sc phases will be significantly coarsened. Although a gradient eutectic phase can be formed, the coarse phase at the grain boundary will increase, resulting in a decrease in mechanical properties. In addition, hot rolling can promote the dissolution of coarse phases and the precipitation of nano-scale precipitation phases. In this application, due to the formation of Al-Mg, Al-Si, and Al-Ni eutectics, coarse phases are formed near adjacent grain boundaries. Hot rolling can effectively eliminate coarse phases near multiple grain boundaries, resulting in significant crack healing and elimination of Al-Mg, Al-Si, and Al-Ni eutectic grain boundary casting defects.

[0112] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A high-strength heat-resistant aluminum alloy, characterized in that: It includes the following components by weight: Ni 4-6%; Ti 0.5-1%; Zr 0.5-1%; Si 0.1-0.5%; Mg 0.1-0.5%; Cu 1-5%; Sc0.1-0.5%; the balance is Al.

2. A high-strength heat-resistant aluminum alloy according to claim 1, characterized in that: The aluminum alloy comprises the following components by weight: Ni 4.5~5.5%; Ti 0.6-0.8%; Zr 0.5-0.7%; Si 0.1-0.4%; Mg 0.2-0.5%; Cu 3-5%; Sc 0.1-0.4%; the balance is Al.

3. A method for preparing a high-strength heat-resistant aluminum alloy, characterized in that: The following steps are involved: S1, weigh appropriate amounts of pure aluminum, pure copper, pure magnesium, Al-Si master alloy, Al-Sc master alloy, Al-Zr master alloy, Al-Ti master alloy, and Al-Ni master alloy according to the composition of the high-strength heat-resistant aluminum alloy for later use; S2, adding the pure aluminum in S1 into a resistance furnace for alloy melting, adding the remaining components in S1 after Al is completely melted, stirring, and then refining and degassing while stirring continuously, and obtaining an alloy ingot after slag removal and casting; S3, then heat-treating the alloy ingot in a muffle furnace, and then hot-rolling the alloy ingot after cooling to obtain an alloy hot-rolled plate, and then performing solid solution treatment and room temperature water quenching on the alloy hot-rolled plate to obtain a high-strength heat-resistant aluminum alloy.

4. The method for preparing a high-strength heat-resistant aluminum alloy according to claim 3, characterized in that: In step S1, the elements added are calculated by weight as follows: Ni 4-6%; Ti 0.5-1%; Zr 0.5-1%; Si 0.1-0.5%; Mg 0.1-0.5%; Cu 1-5%; Sc0.1-0.5%; the balance is Al.

5. The method for preparing a high-strength heat-resistant aluminum alloy according to claim 3, characterized in that: In step S2, the alloy is melted at a temperature of 700-750°C; and / or, in step S2, the refining time is 10-30 min; And / or, in step S2, the obtained alloy ingot is 70 mm×25 mm×10 mm.

6. The method for preparing a high-strength heat-resistant aluminum alloy according to claim 3, characterized in that: In step S3, the specific conditions of the heat treatment are: The heating rate is 5-10℃ / min, the temperature is raised to 400℃-500℃ and kept for 12-20h, and then cooled naturally.

7. The method for preparing a high-strength heat-resistant aluminum alloy according to claim 3, characterized in that: The specific conditions of the hot rolling are: Keep warm at 500-600℃ for 1-3h and hot roll to 5mm. The rolling direction is the length direction of the plate and the pressing amount per single pass is 0.1-0.2mm.

8. The method for preparing a high-strength heat-resistant aluminum alloy according to claim 3, characterized in that: The specific conditions of the solution treatment are: The temperature is 500-600°C and the time is 1-2h, preferably the temperature is 560°C and the time is 1h.

9. A high-strength and heat-resistant aluminum alloy obtained by the method for preparing the high-strength and heat-resistant aluminum alloy as claimed in any one of claims 3 to 8.

10. Use of the high-strength and heat-resistant aluminum alloy according to any one of claims 1, 2 or 9 in the preparation of a piston.

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