阅读说明：本技术 一种Al-Cu-Mg-Ag-Si-Sc耐热合金及制备工艺 (Al-Cu-Mg-Ag-Si-Sc heat-resistant alloy and preparation process thereof ) 是由 文胜平 赵志浩 聂祚仁 黄晖 高坤元 吴晓蓝 于 2019-11-01 设计创作，主要内容包括：一种Al-Cu-Mg-Ag-Si-Sc耐热合金及制备工艺,属于合金材料技术领域。在铝基体加入重量百分比为：2％～4.5％Cu,0.3～0.7％Mg,0～0.6％Ag,0～0.3％Si,0.05％～0.25％Sc。制备方法：在熔炼温度为790±10℃下,将铝锭熔化,加入Al-Cu、Al-Ag、Al-Si、Al-Sc中间合金和纯镁块,待其熔化后,除气,搅拌,保温静置,浇铸并热处理。处理工艺：合金铸锭在540～570℃固溶处理12～24h后水淬至室温；然后将固溶态合金在150～175℃进行等温时效处理。本发明合金在225～250℃长时间热暴露处理能够保持较高的强度,具有良好的热稳定性。(An Al-Cu-Mg-Ag-Si-Sc heat-resistant alloy and a preparation process thereof, belonging to the technical field of alloy materials. The aluminum matrix comprises the following components in percentage by weight: 2 to 4.5 percent of Cu, 0.3 to 0.7 percent of Mg, 0 to 0.6 percent of Ag, 0 to 0.3 percent of Si and 0.05 to 0.25 percent of Sc. The preparation method comprises the following steps: melting the aluminum ingot at the smelting temperature of 790 +/-10 ℃, adding Al-Cu, Al-Ag, Al-Si, Al-Sc intermediate alloy and pure magnesium blocks, degassing after melting, stirring, keeping the temperature, standing, casting and carrying out heat treatment. The treatment process comprises the following steps: carrying out solution treatment on the alloy cast ingot at 540-570 ℃ for 12-24 h, and then carrying out water quenching to room temperature; and then carrying out isothermal aging treatment on the solid solution alloy at 150-175 ℃. The alloy disclosed by the invention can keep higher strength after long-time heat exposure treatment at 225-250 ℃, and has good thermal stability.)

1. An Al-Cu-Mg-Ag-Si-Sc heat-resistant alloy is characterized in that trace Si and Sc are added into an Al-Cu-Mg-Ag matrix, wherein the weight percentage of each element in the Al-Cu-Mg-Ag-Si-Sc heat-resistant alloy is as follows: 2 to 4.5 percent of Cu, 0.3 to 0.7 percent of Mg, 0 to 0.6 percent of Ag, 0 to 0.3 percent of Si, 0.05 to 0.25 percent of Sc, and the balance of Al and inevitable impurities.

2. The Al-Cu-Mg-Ag-Si-Sc heat-resistant alloy according to claim 1, wherein the weight percentages of Cu and Si in the Al-Cu-Mg-Ag-Si-Sc alloy are as follows: 3.5 to 4.5 percent of Cu and 0.1 to 0.3 percent of Si.

3. A method of producing an Al-Cu-Mg-Ag-Si-Sc heat-resistant alloy according to claim 1 or 2, characterized by comprising the steps of: melting an aluminum ingot at the smelting temperature of 790 +/-10 ℃, then adding Al-Cu, Al-Ag, Al-Si, Al-Sc intermediate alloy and a pure magnesium block, degassing by using hexachloroethane after the aluminum ingot is melted, stirring, preserving heat and standing for 30min, and carrying out iron mold casting after all element components in a melt are uniformly distributed; and then heat treatment is carried out to obtain the alloy material.

4. The method of claim 3, wherein the heat treatment process step comprises the following:

(1) firstly, carrying out solution treatment at 540-570 ℃ for 12-24 h, and then carrying out water quenching to room temperature;

(2) and then carrying out isothermal aging treatment on the solid solution alloy at the temperature of 150-175 ℃, wherein the optimal aging temperature is about 175 ℃.

5. The method as claimed in claim 4, wherein the alloy after the heat treatment process can maintain high strength and good thermal stability after long-term heat exposure at 225-250 ℃.

Technical Field

The invention belongs to the technical field of alloy materials, and particularly relates to a preparation method and a heat treatment process of a microalloyed heat-resistant aluminum alloy material.

Technical Field

In recent years, with the development of high and new technologies such as aviation, aerospace and the like, higher and higher requirements are also put forward on the high-temperature performance of the aluminum alloy; microalloying is always an important means for improving the alloy performance and further developing novel aluminum alloys, and has become a hot spot of concern in the material field at home and abroad.

Researchers can change the aging precipitation sequence of the Al-Cu-Mg alloy by adding a certain amount of Ag into the Al-Cu-Mg alloy, and Ringer et Al adopt APFIM to discover that the Al-Cu-Mg alloy mainly contains Mg-Cu atomic clusters in the initial aging period, and the addition of Ag enables a large amount of Mg-Ag atomic clusters to be formed in the initial aging period, and the atomic clusters promote the precipitation of omega phase. Omega looks at (111)_αThe disk exists like a surface because (111)_αIs the main slip plane of the aluminum alloy, so the relative dislocation slip of omega plays a larger role of hindrance, thereby improving the strength of the alloy; and the omega phase has excellent coarsening resistance and can be used for a long time at the temperature of below 200 ℃.

However, the morphology of the new precipitated phase is mostly disc-shaped, the lattice mismatching degree between the lath and the matrix is large, and the interface energy is high, so that the precipitated phase has a high coarsening speed at a high temperature of more than 200 ℃, and the further improvement of the high-temperature service performance is limited. Therefore, a method of adding a proper amount of rare earth elements such as Sc, Yb and Ce is adopted at home and abroad to improve the shape distribution of precipitated phases of the alloy, so as to reduce the lattice mismatching degree between the precipitated phases and a matrix, thereby improving the heat resistance. And trace rare earth element Sc is added into the Al-Cu-Mg alloy, so that fine dispersed Al which is compatible with the matrix can be formed at higher temperature₃The Sc heat-resistant phase inhibits the growth of second phase grains and improves the high-temperature strength of the alloy; simultaneously, dislocation, substructure and grain boundary can be pinned, and the organization structure is stabilized. However, the diffusion rate of elements such as Sc, Yb, and Ce is low, and a high temperature (250 ℃ or higher) is required to suppress coarsening by the segregation around the precipitated phase. The effect of aging strengthening of the alloy at this temperature is poor, and the strength of the alloy is low although a thermally stable precipitated phase can be obtained.

On the basis of the technical background, the novel Al-Cu-Mg-Ag-Si-Sc high-strength heat-resistant alloy is prepared by carrying out Si and Sc composite micro-alloying and combining a proper preparation method and a proper heat treatment process.

Disclosure of Invention

The invention aims to prepare the Al-Cu-Mg-Ag-Si-Sc high-strength heat-resistant alloy by a Si and Sc microalloying method and by exerting the synergistic effect of microalloying elements on the optimal matrix components and heat treatment process.

The Al-Cu-Mg-Ag-Si-Sc heat-resistant alloy is characterized in that trace Si and Sc are added into an Al-Cu-Mg-Ag matrix, wherein the weight percentage of each element in the Al-Cu-Mg-Ag-Si-Sc heat-resistant alloy is as follows: 2 to 4.5 percent of Cu, 0.3 to 0.7 percent of Mg, 0 to 0.6 percent of Ag, 0 to 0.3 percent of Si, 0.05 to 0.25 percent of Sc, and the balance of Al and inevitable impurities.

The optimal component ranges of the alloy elements are as follows (weight percentage): 3.5 to 4.5 percent of Cu and 0.1 to 0.3 percent of Si.

The preparation method of the alloy is characterized by comprising the following steps of: melting an aluminum ingot at the smelting temperature of 790 +/-10 ℃, then adding Al-Cu, Al-Ag, Al-Si, Al-Sc intermediate alloy and a pure magnesium block, degassing by using hexachloroethane after the aluminum ingot is melted, stirring, preserving heat and standing for 30min, and carrying out iron mold casting after all element components in a melt are uniformly distributed; and then heat treatment is carried out to obtain the alloy material.

The alloy heat treatment process steps of the invention comprise the following (wherein, the method for determining the optimal process is also included):

(1) firstly, carrying out solution treatment at 540-570 ℃ for 12-24 h, and then carrying out water quenching to room temperature;

(2) and then carrying out isothermal aging treatment on the solid solution alloy at the temperature of 150-175 ℃, wherein the optimal aging temperature is about 175 ℃.

(3) And (3) placing the alloy with the aging peak value at 175 ℃ at 225-250 ℃ for long-time heat exposure, and detecting the high-temperature strength and the heat stability of the alloy.

According to the invention, Si and Sc composite micro-alloying is adopted, and the heat treatment process is adopted, so that the synergistic effect of Si and Sc elements is exerted on the optimal basic alloy, the Si and Sc elements can be segregated around a precipitated phase at a lower aging temperature (between 150 and 175 ℃), the growth and coarsening of the precipitated phase or the generation of a new precipitated phase are inhibited, and the alloy has higher strength and a remarkable heat-resistant effect at the same time. As shown in the attached figures 2 and 5, the hardness of the alloy A3 is always higher than that of the alloy A1 and the alloy A2 when the alloy A is exposed to heat at 225 ℃ and 250 ℃ for a long time; and the strength is still higher at the temperature of 225 ℃ for 850h and at the temperature of 250 ℃ for more than 400h, so that the alloy has good high-temperature thermal stability.

Drawings

FIG. 1: hardness curves of the A1, A2 and A3 alloys after isothermal aging at 150 ℃ and thermal exposure at 225 ℃;

FIG. 2: hardness curves of the A1, A2 and A3 alloys after isothermal aging at 175 ℃ and thermal exposure at 225 ℃;

FIG. 3: hardness curves for the a3 alloy at 225 ℃ heat exposure after 150 ℃ isothermal aging and 175 ℃ isothermal aging;

FIG. 4: hardness curves of the A4, A5 and A6 alloys after isothermal aging at 175 ℃ and thermal exposure at 225 ℃;

FIG. 5: hardness curves of the A1, A2, A3 alloys after isothermal aging at 175 ℃ and heat exposure at 250 ℃.

Detailed Description

The present invention will be further illustrated with reference to the following examples, but the present invention is not limited to the following examples.