A kind of Al-Cu-Mg-Ag-Si-Sc-Mn-Zr high-strength and high-heat-resistant aluminum alloy and preparation method thereof

Abstract

The present invention belongs to the field of new material design, and the alloy provided is Al‑Cu‑Mg‑Ag‑Si‑Sc‑Mn‑Zr, and its composition range is: Cu is 3.8-4.6wt%, Mg is 0.5-1.0wt%, Ag is 0.5-1.0wt%, Si is 0.3-0.5wt%, Sc is 0.05-0.25wt%, Mn is 0.2-0.5wt%, Zr is 0.05-0.15wt%, and the balance is Al element. The basic preparation method of the alloy provided by the present invention is: vacuum induction melting → iron mold casting → homogenization treatment → hot rolling deformation → solution aging. After all the process treatments, the alloy provided by the present invention has high yield strength and tensile strength at room temperature and 210°C, and has high durability at 210°C.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloys, and in particular relates to an Al-Cu-Mg-Ag-Si-Sc-Mn-Zr high-strength and high-heat-resistant aluminum alloy and a preparation method thereof, and specifically relates to the composition and preparation process of a new type of heat-resistant deformation aluminum alloy, as well as the tensile properties of the alloy at room temperature and 210°C, and the endurance performance at 210°C. Background Art

[0002] The main precipitation strengthening phase of the traditional Al-Cu aluminum alloy is the θ' phase (Al2Cu). After adding Mg and Ag elements, a core-shell structure precipitation phase Ω phase (Al2Cu-Ag / Mg) will be formed. The Ω phase is precipitated from the matrix with the Ag-Mg atomic cluster as the nucleation center, and has the characteristics of high-density precipitation, dispersed distribution and high strengthening effect. The interface between the θ' phase and the Al matrix easily attracts the segregation of solute atoms, which can significantly inhibit the coarsening of the θ' phase at high temperatures and improve the high-temperature stability of the microstructure. How to further improve the performance of aluminum alloys has become a hot topic in this field. Summary of the invention

[0003] In view of this, the object of the present invention is to provide an Al-Cu-Mg-Ag-Si-Sc-Mn-Zr high-strength and high-heat-resistant aluminum alloy and a preparation method thereof. The aluminum alloy provided by the present invention has better performance by coordinating the strengthening effect of various precipitated phases.

[0004] The present invention provides an Al-Cu-Mg-Ag-Si-Sc-Mn-Zr high-strength and high-heat-resistant aluminum alloy, the composition of which is:

[0005] Cu 3.8~4.6wt%

[0006] Mg 0.5~1.0wt%

[0007] Ag 0.5~1.0wt%

[0008] Si 0.3~0.5wt%

[0009] Sc 0.05~0.25wt%

[0010] Mn 0.2~0.5wt%

[0011] Zr 0.05~0.15wt%

[0012] The balance is Al.

[0013] The present invention provides a method for preparing the Al-Cu-Mg-Ag-Si-Sc-Mn-Zr high-strength and high-heat-resistant aluminum alloy described in the above technical solution, comprising:

[0014] After mixing the ingredients according to the alloy composition, smelting and casting are performed to obtain an alloy ingot;

[0015] The alloy ingot is subjected to homogenization treatment, thermal deformation, solution treatment and aging treatment to obtain a high-strength and high-heat-resistant aluminum alloy.

[0016] Preferably, the raw materials of the ingredients include:

[0017] Pure Al, Al-Cu master alloy, pure Mg, pure Ag, Al-Si master alloy, Al-Sc master alloy, Al-Mn master alloy and Al-Zr master alloy.

[0018] Preferably, the smelting method is vacuum induction melting.

[0019] Preferably, the casting is iron mold casting.

[0020] Preferably, the homogenization treatment is carried out at a temperature of 490 to 510° C. and for a time of 24 to 48 hours.

[0021] Preferably, the thermal deformation method is rolling.

[0022] Preferably, the rolling temperature is 350-450°C.

[0023] Preferably, the temperature of the solution treatment is 520-540° C., and the time is 2-6 hours.

[0024] Preferably, the aging treatment is performed at a temperature of 150 to 200° C. and for a time of 5 to 20 hours.

[0025] In the present invention, σ phase (Al5Cu6Mg2) is a new aging precipitation phase found in the Al-Cu-Mg system containing Si element. σ phase is a stable precipitation phase, which can remain insoluble in the matrix and maintain its morphology under high temperature conditions above 250°C. σ phase is a very potential heat-resistant strengthening phase. The addition of Si can form a C / L-MgSiCu phase at the interface between the θ' phase and the Al matrix, and the added Sc element can be concentrated at the interface between the θ' phase and the Al matrix, both of which can improve the stability of the θ' phase at high temperatures; the addition of Mn atoms can promote the T phase (Al 20 Cu2Mn3) precipitation, while the addition of transition element Zr can form Al3Zr precipitation phase coherent with the matrix. T phase and Al3Zr phase can pin dislocations and inhibit grain growth, further improving the stability of the alloy's high temperature structure.

[0026] The present invention uses Al-Cu-Mg-Ag-Si-Sc-Mn-Zr as an alloy system, obtains a precipitation strengthening phase θ' phase by adding Cu element, obtains a strengthening phase Ω phase by adding Mg and Ag elements, adjusts the content of Cu and Mg elements to obtain a precipitation strengthening phase σ phase, adds Si and Sc elements to form a segregation layer around the θ' phase, adds Mn and Zr elements to obtain strengthening phases such as T phase and Al3Zr phase, and combines suitable preparation processes such as melting and casting, hot and cold deformation and solution aging to obtain a new heat-resistant aluminum alloy, which has excellent tensile properties at room temperature and 210°C, and good endurance performance at 210°C.

[0027] The alloy provided by the present invention is based on the simultaneous strengthening of the θ' phase (Al2Cu) with interface segregation effect and the Ω phase (Al2Cu-Ag / Mg) with core-shell structure, and the T phase (Al2Cu-Ag / Mg) is used to strengthen the interface segregation effect. 20 The combined strengthening effect of Cu2Mn3), σ phase (Al5Cu6Mg2) and Al3Zr phase enables the alloy to obtain higher room temperature and high temperature strength and endurance performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Nanoscale microstructure of the aluminum alloy prepared in the embodiment of the present invention under the

[001] crystal axis, (a) dark field image; (b) HAADF-STEM image; (cd) HRTEM of the precipitated phase;

[0029] Figure 2 This is a nanoscale microstructure diagram of the aluminum alloy prepared in an embodiment of the present invention under the

[110] crystal axis. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The present invention provides an Al-Cu-Mg-Ag-Si-Sc-Mn-Zr high-strength and high-heat-resistant aluminum alloy, the composition of which is:

[0032] Cu 3.8~4.6wt%

[0033] Mg 0.5~1.0wt%

[0034] Ag 0.5~1.0wt%

[0035] Si 0.3~0.5wt%

[0036] Sc 0.05~0.25wt%

[0037] Mn 0.2~0.5wt%

[0038] Zr 0.05~0.15wt%

[0039] The balance is Al.

[0040] In the present invention, the mass content of Cu is preferably 4.0-4.4%, more preferably 4.2%; the mass content of Mg is preferably 0.6-0.9%, more preferably 0.7-0.8%; the mass content of Ag is preferably 0.6-0.9%, more preferably 0.7-0.8%; the mass content of Si is preferably 0.4%; the mass content of Sc is preferably 0.10-0.20%, more preferably 0.15%; the mass content of Mn is preferably 0.3-0.4%; the mass content of Zr is preferably 0.08-0.12%, more preferably 0.1%.

[0041] Figure 1 The nanoscale microstructure of the aluminum alloy prepared in the embodiment of the present invention under the

[001] crystal axis. Figure 1 From ab, we can see that a lot of nanoscale σ phases are produced in the aluminum alloy; Figure 1 cd shows that there is a C / L-MgSiCu phase at the interface between the main strengthening phase θ′-Al2Cu phase and the Al matrix. This phase acts as a segregated layer to improve the thermal stability of the θ′-Al2Cu phase. Figure 2 It can be determined that the aluminum alloy provided by the present invention contains, in addition to θ′-Al2Cu, an Ω phase having a core-shell structure, the shell layer of which is a regularly arranged Ag-Mg atomic layer.

[0042] The present invention provides a method for preparing the Al-Cu-Mg-Ag-Si-Sc-Mn-Zr high-strength and high-heat-resistant aluminum alloy described in the above technical solution, comprising:

[0043] After mixing the ingredients according to the alloy composition, smelting and casting are performed to obtain an alloy ingot;

[0044] The alloy ingot is subjected to homogenization treatment, thermal deformation, solution treatment and aging treatment to obtain a high-strength and high-heat-resistant aluminum alloy.

[0045] In the present invention, the raw materials of the batch preferably include: pure Al, Al-Cu master alloy, pure Mg, pure Ag, Al-Si master alloy, Al-Sc master alloy, Al-Mn master alloy and Al-Zr master alloy.

[0046] In the present invention, the smelting method preferably adopts vacuum induction melting, and the raw materials are preferably placed in a crucible. In the present invention, during the smelting process, the alloy raw materials are first placed in a graphite crucible and vacuumized; after the vacuum degree reaches 30-70Pa, preferably 40-60Pa, and more preferably 50Pa, argon gas is filled into the furnace; then induction melting is started, and the current is preferably 200-220A, and more preferably 210A; preferably, the raw materials are kept warm for 5-10 minutes after they are completely melted, and the crucible is shaken to ensure that the composition of the melt is uniform.

[0047] In the present invention, the casting is preferably iron mold casting; in the casting process, the alloy melt is preferably poured into the mold after the insulation is completed, and the furnace is opened for sampling after the melt is cooled.

[0048] In the present invention, the method for preparing the alloy ingot preferably comprises:

[0049] According to the alloy element ratio, weigh the required raw materials such as pure Al, Al-Cu master alloy, pure Mg, pure Ag, Al-Si master alloy, Al-Sc master alloy, Al-Mn master alloy and Al-Zr master alloy; then place the raw materials in the graphite crucible of the vacuum induction furnace, evacuate the furnace, and fill the furnace with argon gas for smelting protection; continue to keep the raw materials warm after they are completely melted, and shake the crucible during the warming process to make the melt components spread evenly; then, cast the alloy melt into the iron mold, and open the furnace for sampling after it cools down. The size of the resulting ingot is about Φ30mm×110mm.

[0050] In the present invention, the temperature of the homogenization treatment is preferably 490-510°C, more preferably 495-505°C, and most preferably 500°C; the time of the homogenization treatment is preferably 24-48 hours, more preferably 30-40 hours, and most preferably 35 hours.

[0051] In the present invention, the homogenization treatment is preferably followed by air cooling to room temperature.

[0052] In the present invention, the method of thermal deformation is preferably rolling; the rolling temperature is preferably 350-450°C, more preferably 380-420°C, and most preferably 400°C. In the present invention, in the rolling process, the alloy is preferably heated to the rolling temperature and then kept warm before rolling. After each rolling pass, the alloy is preferably returned to keep warm, and the alloy is preferably rolled to 1-3 mm in the end; the keeping warm is preferably carried out in a resistance furnace; the keeping warm time is preferably 1-2 hours, more preferably 1.5 hours; the reduction per pass is preferably 2-4 mm, more preferably 2.5-3.5 mm, and most preferably 3 mm; the alloy is preferably rolled to 2 mm in the end.

[0053] In the present invention, the temperature of the solution treatment is preferably 520-540°C, more preferably 525-535°C, and most preferably 520°C; the time of the solution treatment is preferably 2-6 hours, more preferably 3-4 hours. In the present invention, the solution treatment is preferably water quenched to room temperature.

[0054] In the present invention, the aging treatment is preferably isothermal aging treatment; the temperature of the aging treatment is preferably 150-200°C, more preferably 160-190°C, most preferably 170-180°C; the time of the aging treatment is preferably 5-20 hours, more preferably 10-15 hours.

[0055] After the aluminum alloy provided by the present invention has undergone all the above-mentioned processes, the tensile properties of the alloy are tested at room temperature and 210° C., and the endurance properties of the alloy are tested at 210° C. The test results show that the alloy prepared by the present invention has excellent room temperature / high temperature tensile properties and endurance properties.

[0056] Embodiment 1 to Embodiment 3

[0057] According to the alloy element ratio, weigh the required raw materials such as pure Al, Al-Cu master alloy, pure Mg, pure Ag, Al-Si master alloy, Al-Sc master alloy, Al-Mn master alloy and Al-Zr master alloy. Then place the raw materials in the graphite crucible of the vacuum induction furnace, evacuate it, and fill the furnace with argon gas for smelting protection. After the raw materials are completely melted, continue to keep them warm, and shake the crucible during the insulation process to evenly diffuse the melt components. After that, cast the alloy melt into an iron mold, and open the furnace for sampling after it cools down. The size of the resulting ingot is about Φ30mm×110mm.

[0058] Three Al-Cu-Mg-Ag-Si-Sc-Mn-Zr alloys with different compositions were prepared by the above method, and the obtained ingots were subjected to ICP test to obtain their actual compositions, as shown in Table 1:

[0059] Table 1 Alloy composition prepared in Example

[0060]

[0061] The alloy ingot was homogenized at 500°C and kept warm for 36 hours. The ingot was then air-cooled to room temperature. 5mm was cut off from the head and tail of the homogenized alloy to ensure that there were no defects at both ends, and the surface of the alloy was smoothed with sandpaper. The alloy was then placed in a resistance furnace and heated to 450°C and kept warm for 1 hour, and then hot rolling was started, with the reduction in each pass controlled at about 2mm. After each rolling pass, the alloy was returned to the resistance furnace and kept warm for about 20 minutes. Finally, the alloy was rolled to about 2mm. The rolled alloy was solutionized at 530°C for 4 hours, and then quenched in water to room temperature. The solution alloy was subjected to isothermal aging heat treatment at 180°C for 8 hours.

[0062] The prepared high-strength and high-heat-resistant aluminum alloy was sampled along the rolling length direction, and the tensile properties were tested under the conditions of room temperature, 210℃ and 210℃ endurance, respectively. The detection method is: room temperature tensile test using HB5143; 210℃ tensile test using HB5195; 210℃ endurance test using HB5150. The mechanical properties test results are shown in Tables 2, 3 and 4.

[0063] Table 2 Room temperature mechanical properties test results of alloys prepared in Example

[0064] Example 1 Example 2 Example 3 <![CDATA[σ 0.2 (MPa)]]> 403 411 433 <![CDATA[σ b (MPa)]]> 433 445 466

[0065] Table 3 Test results of mechanical properties of alloys prepared in Example at 210°C

[0066] Example 1 Example 2 Example 3 <![CDATA[σ 0.2 (MPa)]]> 380 387 395 <![CDATA[σ b (MPa)]]> 386 395 406

[0067] Table 4 210℃ endurance test results of alloys prepared in Example

[0068] state Example 1 Example 2 Example 3 220MPa 38 hours 43 hours 49 hours 190MPa 137 hours 153 hours 168 hours

[0069] In order to compare the performance, two heat-resistant aluminum alloys 2618 and 2024 were prepared by the same method as the embodiment of the present invention, and room temperature tensile, 210°C tensile and 210°C endurance tests were performed on them; the measured properties are shown in Table 5; As can be seen from Table 5, the room temperature strength of the aluminum alloy prepared in the embodiment of the present invention is close to that of the 2618 and 2024 alloys, but the strength at 210°C and the endurance time under 220 / 190MPa stress at 210°C are much higher than those of the two alloys.

[0070] Table 5 Performance comparison of aluminum alloy, 2618 alloy and 2024 alloy prepared in the embodiment of the present invention

[0071]

[0072] The present invention uses Al-Cu-Mg-Ag-Si-Sc-Mn-Zr as an alloy system, obtains a precipitation strengthening phase θ' phase by adding Cu element, obtains a strengthening phase Ω phase by adding Mg and Ag elements, adjusts the content of Cu and Mg elements to obtain a precipitation strengthening phase σ phase, adds Si and Sc elements to form a segregation layer around the θ' phase, adds Mn and Zr elements to obtain strengthening phases such as T phase and Al3Zr phase, and combines suitable preparation processes such as melting and casting, hot and cold deformation and solution aging to obtain a new heat-resistant aluminum alloy, which has excellent tensile properties at room temperature and 210°C, and good endurance performance at 210°C.

[0073] Although the present invention has been described and illustrated with reference to specific embodiments of the present invention, these descriptions and illustrations do not limit the present invention. It will be clearly understood by those skilled in the art that various changes may be made without departing from the true spirit and scope of the present invention as defined by the appended claims, so that specific circumstances, materials, material compositions, materials, methods or processes are suitable for the goals, spirit and scope of the present application. All such modifications are intended to be within the scope of the appended claims. Although the methods disclosed herein have been described with reference to specific operations performed in a specific order, it should be understood that these operations may be combined, subdivided or reordered to form equivalent methods without departing from the teachings of the present invention. Therefore, unless specifically indicated herein, the order and grouping of operations are not limitations of the present application.

Claims

1. An Al-Cu-Mg-Ag-Si-Sc-Mn-Zr high-strength and high-heat-resistant aluminum alloy, the composition is: Cu 4.48wt%, Mg 0.9wt%, Ag 0.85wt%, Si 0.43wt%, Sc 0.2wt%, Mn 0.47wt%, Zr 0.14wt%, The balance is Al; the preparation method of the Al-Cu-Mg-Ag-Si-Sc-Mn-Zr high-strength and high-heat-resistant aluminum alloy comprises: After mixing the ingredients according to the alloy composition, smelting and casting are performed to obtain an alloy ingot; The alloy ingot is subjected to homogenization treatment, thermal deformation, solution treatment and aging treatment to obtain a high-strength and high-heat-resistant aluminum alloy; The homogenization temperature is 500°C and the time is 36h; The thermal deformation method is: The alloy was heated to 450°C and kept at this temperature for 1 hour, and then hot rolled. After each rolling pass, the alloy was returned to the resistance furnace and kept at this temperature for 20 minutes; The solution treatment temperature is 530°C and the time is 4h; The temperature of the aging treatment is 180° C. and the time is 8 hours.

2. The high-strength and high-heat-resistant aluminum alloy according to claim 1, characterized in that: The raw materials of the ingredients include: Pure Al, Al-Cu master alloy, pure Mg, pure Ag, Al-Si master alloy, Al-Sc master alloy, Al-Mn master alloy and Al-Zr master alloy.

3. The high-strength and high-heat-resistant aluminum alloy according to claim 1, characterized in that: The smelting method is vacuum induction melting.

4. The high-strength and high-heat-resistant aluminum alloy according to claim 1, characterized in that: The casting is iron mold casting.

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