A heterogeneous bimodal grain heat-resistant aluminum alloy overcoming high-temperature softening effect and a preparation method thereof

Abstract

The application discloses a heterogeneous bimodal grain heat-resistant aluminum alloy overcoming high-temperature softening effect and a preparation method thereof. First, a rare earth aluminum alloy ingot is prepared by a gravity casting method, and then a cylindrical material is cut from the ingot as a blank. The blank is subjected to hot extrusion to obtain a heterogeneous bimodal grain heat-resistant aluminum alloy rod. The application uses the hot extrusion method which is low in cost and easy to industrialize to prepare the aluminum alloy rod, and forms a heterogeneous bimodal grain structure in which fiber-shaped coarse grains are embedded in equiaxed fine grains. The average grain size of the equiaxed fine grains is 1.6 microns, and the average grain size of the fiber-shaped coarse grains is 6.7 microns. The equiaxed fine grains improve the strength, and the fiber-shaped coarse grains provide plasticity. The combination of the coarse and fine grains makes the room-temperature tensile strength of the alloy greater than 260 MPa, the elongation after fracture greater than 10%, the high-temperature tensile strength greater than 100 MPa, and the high-temperature elongation after fracture greater than 17%.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy materials, and specifically to a method for preparing a heterogeneous bimodal grain Al-La alloy that overcomes the high-temperature softening effect by hot extrusion of ingots. Background Technology

[0002] Al alloys are widely used in rail transportation, automobiles and aerospace due to their advantages of lightweight components and high economic efficiency. Heat-resistant Al alloys can reduce costs by replacing titanium with aluminum under medium temperature (200-400℃) service conditions by stabilizing the microstructure and suppressing high temperature softening behavior.

[0003] Near-eutectic Al-La alloys exhibit excellent casting properties, and due to the low diffusion rate of La, the resulting eutectic structure is less prone to coarsening, resulting in higher thermal stability. Adding Sc and Zr can further enhance high-temperature mechanical properties by forming a two-scale second-phase strengthening process. Plastic deformation can improve microstructure defects, control grain refinement, and regulate microstructure flow, and is widely used in aluminum production. Hot extrusion, a plastic deformation method, is well-suited to my country's national conditions and has greater potential for application.

[0004] During hot deformation, the second phase with a particle size greater than 1 μm promotes recrystallization through particle-stimulated nucleation (PSN effect) and inhibits the growth of equiaxed grains after recrystallization through pinning effect. Conversely, the submicron-scale second phase delays the recrystallization process, resulting in coarse fibrous grains. The resulting material grain structure is characterized by heterogeneous bimodal grains with fibrous coarse grains embedded in equiaxed fine grains. The coarse grains enhance high-temperature strength by inhibiting fine grain deformation, while intermetallic compounds further enhance strength by hindering dislocation and grain boundary migration. This study provides a new approach to the microstructure design of heat-resistant aluminum alloys and expands the application prospects of heterogeneous grain structures.

[0005] The literature (Ultrafine-grained Al-La-Mg-Mn alloy fabricated by melt spinning and hot extrusion with ultrahigh strength and thermal stability. Tao Ban, ZhiWang, Liejun Li, Zhuoran Li, Xinkui Zhang, Zhengwu Peng. Journal of Alloys and Compounds 1007 (2024) 176421) describes the preparation of Al-La-Mg-Mn alloy strips using melt spinning and hot extrusion, followed by cold pressing and hot extrusion processes to obtain an ultrafine-grained structure with a grain size of approximately 0.56 μm. A high volume fraction of Al was formed in the alloy. 11 Intermetallic compounds such as La3 and Al6Mn, through multiple mechanisms such as solid solution strengthening, grain refinement strengthening, Orowan strengthening and heterostructure strain hardening, have achieved a tensile strength of 621 MPa and good thermal stability (the strength only decreases by 15% after 200 hours of exposure at 400°C). However, the following shortcomings still exist: (1) The process is complex and costly: the melt fast casting + hot extrusion process is long and the equipment requirements are high, which is not conducive to large-scale industrial application. (2) The material plasticity is limited: although the elongation reaches 6.8%, it is still insufficient for some high plasticity forming scenarios, and there are defects such as secondary cracks at the interface. (3) The high-temperature mechanical properties still need to be clarified. Summary of the Invention

[0006] The purpose of this invention is to provide a heterogeneous bimodal grain heat-resistant aluminum alloy and its preparation method. This invention overcomes the high-temperature softening effect through a hot extrusion process. This method can obtain a rare-earth aluminum alloy with heterogeneous bimodal grains (fiber-like coarse grains embedded with equiaxed fine grains), low compositional segregation, and excellent room-temperature and high-temperature properties. Compared with the as-cast alloy, the room-temperature yield strength increases from 127 MPa (as-cast) to 246 MPa (hot-extruded), and the tensile strength increases from 144 MPa (as-cast) to 281 MPa (hot-extruded), while the plasticity increases from 2.5% (as-cast) to 11% (hot-extruded). The high-temperature yield strength increases from 59 MPa (as-cast) to 93 MPa (hot-extruded), while the tensile strength and plasticity remain similar, at 96 MPa (as-cast) and 100 MPa (hot-extruded), and 17.8% (as-cast) and 17.4% (hot-extruded), respectively. Furthermore, this invention has low operating costs, utilizes mature hot extrusion technology in the aluminum industry, and has broad application prospects.

[0007] The objective of this invention is achieved through the following technical solutions.

[0008] A heterogeneous bimodal grain heat-resistant aluminum alloy comprises: 5~15 wt.% La, 0.1~1 wt.% Sc, 0~0.5 wt.% Zr, with the balance being Al and unavoidable impurities. Preferably, the Zr content is 0.1~0.5 wt.%.

[0009] The heterogeneous bimodal grain heat-resistant aluminum alloy has a room temperature tensile strength greater than 260 MPa and an elongation after fracture greater than 10%, and a high temperature tensile strength greater than 100 MPa and an elongation after fracture greater than 17%. The rare earth aluminum alloy prepared using this method exhibits excellent room temperature and high temperature properties. Furthermore, the process is simple, low-cost, and suitable for industrial production, showing promising application prospects.

[0010] A method for preparing a heat-resistant aluminum alloy with heterogeneous bimodal grains includes the following steps: (1) The raw materials are melted, impurities are removed and heat is maintained, and then the required alloy ingots are prepared by pressure casting. (2) Take the rare earth aluminum alloy ingot obtained in step (1) and cut a cylindrical material from the area relatively far away from the edge, top and bottom of the ingot. Use sandpaper to grind away the surface wire cutting marks of the cylindrical material and use it as blank. (3) The blank obtained in step (2) is placed in a muffle furnace and kept warm. After a period of time, it is placed in a hot extruder for hot extrusion to obtain the heterogeneous bimodal grain heat-resistant aluminum alloy.

[0011] Further, in step (1), the raw materials are pure aluminum ingots, Al-La master alloys and Al-Sc master alloys, or pure aluminum ingots, Al-La master alloys, Al-Sc master alloys and Al-Zr master alloys.

[0012] Furthermore, in step (1), the melting temperature is 700~800℃, the holding temperature is 700~800℃, and the holding time is 10~30min.

[0013] Furthermore, in step (3), the insulation temperature of the blank is 350~550℃ and the insulation time is 15min~30min.

[0014] Further, in step (3), the hot extrusion temperature is 350~550℃, the extrusion ratio is 10~40, and the extrusion pressure is 500~2000KN.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) This invention uses the relatively inexpensive rare earth element La to prepare Al-La alloys. On the one hand, due to the low solid solubility and low diffusion coefficient of element La in the Al matrix, the Al formed by its reaction with Al... 11The La3 second phase does not coarsen easily at high temperatures, thus giving the alloy excellent high-temperature resistance. On the other hand, by introducing a certain amount of alloying element Sc, nanoscale Al3Sc precipitates are formed, introducing the Orovan strengthening mechanism to improve mechanical properties.

[0016] (2) During the hot deformation process, it breaks down into Al particles with a particle size greater than 1 μm. 11 The La3 second phase promotes the formation of recrystallized grains in the La-rich aluminum matrix through particle-stimulated nucleation (PSN effect) and inhibits the growth of equiaxed grains after recrystallization through pinning effect. Meanwhile, the nanoscale Al3Sc precipitates, during hot extrusion in the absence of Al... 11 The region of the La3 second phase delays the recrystallization process of the aluminum matrix, resulting in coarse fibrous grains.

[0017] (3) This invention utilizes a low-cost, easily industrialized hot extrusion method to prepare aluminum alloy rods, forming a heterogeneous bimodal grain structure with fibrous coarse grains embedded in equiaxed fine grains. The average grain size of the equiaxed fine grains is 1.6 μm, and the average grain size of the fibrous coarse grains is 6.7 μm. The equiaxed fine grains improve strength, while the fibrous coarse grains provide plasticity. The combination of coarse and fine grains results in an alloy with a room temperature tensile strength greater than 260 MPa and an elongation after fracture greater than 10%, and a high temperature tensile strength greater than 100 MPa and an elongation after fracture greater than 17%.

[0018] (4) The present invention improves the high temperature yield strength of the alloy, ensures that the tensile strength and plasticity do not decrease when kept at 300℃, and overcomes the high temperature softening effect. Attached Figure Description

[0019] Figure 1 The image shows the microstructure of the Al-La-Sc aluminum alloy rod obtained in Example 1.

[0020] Figure 2 The image shows the electron backscatter diffraction (EBSD) pattern of the Al-La-Sc-Zr aluminum alloy rod obtained in Example 1.

[0021] Figure 3 This is a grain size distribution diagram of the equiaxed and fibrous grains of the Al-La-Sc-Zr aluminum alloy rod obtained in Example 1.

[0022] Figure 4 The image shows the room temperature tensile stress-strain curve of the Al-La-Sc aluminum alloy bar obtained in Example 1.

[0023] Figure 5 The image shows the stress-strain curve of the Al-La-Sc aluminum alloy bar obtained in Example 1 at 300℃.

[0024] Figure 6The image shows the room temperature tensile stress-strain curve of the Al-La-Sc-Zr aluminum alloy bar obtained in Example 2.

[0025] Figure 7 The image shows the stress-strain curve of the Al-La-Sc-Zr aluminum alloy bar obtained in Example 2 at 300℃.

[0026] Figure 8 The image shows the room temperature tensile stress-strain curve of the Al-La-Sc aluminum alloy bar obtained in Example 3.

[0027] Figure 9 The image shows the room temperature tensile stress-strain curve of the Al-La-Sc-Zr aluminum alloy bar obtained in Example 4.

[0028] Figure 10 The image shows the room temperature tensile stress-strain curve of the Al-La-Sc aluminum alloy bar obtained in Example 5.

[0029] Figure 11 The image shows the room temperature tensile stress-strain curve of the Al-La-Sc-Zr aluminum alloy bar obtained in Example 6. Detailed Implementation

[0030] To facilitate understanding of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0031] The raw materials selected in the examples are pure aluminum ingots, Al-La master alloys, Al-Sc master alloys, and Al-Zr master alloys.

[0032] Example 1 A method for preparing a heat-resistant Al-La-Sc aluminum alloy with heterogeneous bimodal grains, comprising the following steps: (1) Prepare the raw materials according to the following weight ratio: 11.50wt.%La, 0.5wt.%Sc, and the balance is Al. Melt the raw materials in a vacuum induction melting furnace, heat the molten metal to 780℃ and keep it at this temperature for 30 minutes, and then place the molten metal in a vertical four-column hydraulic press to perform extrusion casting to obtain the required ingot. (2) Use a wire cutting machine to cut out cylindrical materials of Φ30mm×30mm as blanks in areas relatively far from the edge, top and bottom of the ingot, and use coarse sandpaper to polish the surface of the blanks to remove wire cutting marks and their oxidation products; (3) The muffle furnace and hot extruder are heated to 450°C and held at that temperature. After the temperature stabilizes, the billet obtained by wire cutting is placed into the muffle furnace and held for 15 minutes. After the holding time is completed, the heated billet is quickly placed into the hot extruder for extrusion. The extrusion temperature is 450°C, the extrusion ratio is 30, and the extrusion pressure is 2000KN to obtain Al-La-Sc aluminum alloy rods.

[0033] Figure 1 The images show the microstructure of the Al-La-Sc aluminum alloy rods obtained in this embodiment. The black contrast represents the aluminum matrix, and the white contrast represents Al. 11 The La3 second phase is distributed in the rod in a granular form with a size distribution between 0.5 and 2 μm.

[0034] Figure 2 and Figure 3 The images show the electron backscatter diffraction (EBSD) pattern and corresponding grain size distribution of the Al-La-Sc aluminum alloy rod prepared by hot extrusion in this embodiment. Figure 3 It can be seen that this aluminum alloy is rich in micron-sized Al. 11 The La3 region exhibits equiaxed grains due to the PSN effect, resulting in small grain sizes with an average size of 1.6 μm; in the absence of micron-sized Al... 11 The La3 region grains are fibrous grains formed due to the delayed recrystallization caused by Al3Sc nanoscale second-phase pinning grain boundaries, with an average grain size of 6.7 μm. The grain size exhibits bimodal grain characteristics, and the grain distribution morphology shows a heterogeneous bimodal grain structure with fibrous coarse grains embedded in equiaxed fine grains (equiaxed fine grains account for 67.5%, and fibrous coarse grains account for 32.5%).

[0035] Figure 4 This is a room temperature tensile stress-strain curve for Al-La-Sc aluminum alloy bars prepared by hot extrusion in this embodiment. Figure 4 It can be seen that the room temperature tensile strength of the aluminum alloy bar is 262 MPa and the elongation after fracture is 11%, indicating that the rare earth aluminum alloy prepared by the method of the present invention has good room temperature mechanical properties.

[0036] Figure 5 This is a high-temperature tensile stress-strain curve at 300℃ for Al-La-Sc aluminum alloy bars prepared by hot extrusion in this embodiment. Figure 5 It can be seen that the room temperature tensile strength of the aluminum alloy bar is 100 MPa and the elongation after fracture is 17.4%, indicating that the rare earth aluminum alloy prepared by the method of the present invention has good high temperature mechanical properties.

[0037] Example 2 A method for preparing a heat-resistant Al-La-Sc-Zr aluminum alloy with heterogeneous bimodal grains, comprising the following steps: (1) Prepare the raw materials according to the following weight ratio: 11.50wt.%La, 0.25wt.%Sc, 0.25wt.%Zr, with the balance being Al. Melt the raw materials in a vacuum induction melting furnace, heat the molten metal to 780℃ and hold it at this temperature for 30 minutes, and then place the molten metal in a vertical four-column hydraulic press to perform extrusion casting to obtain the required ingot. (2) Use a wire cutting machine to cut out cylindrical materials of Φ30mm×30mm as blanks in areas relatively far from the edge, top and bottom of the ingot, and use coarse sandpaper to polish the surface of the blanks to remove wire cutting marks and their oxidation products; (3) The muffle furnace and hot extruder are heated to 450°C and held at that temperature. After the temperature stabilizes, the billet obtained by wire cutting is placed into the muffle furnace and held for 15 minutes. After the holding time is completed, the heated billet is quickly placed into the hot extruder for extrusion. The extrusion temperature is 450°C, the extrusion ratio is 30, and the extrusion pressure is 2000KN to obtain Al-La-Sc-Zr aluminum alloy rods.

[0038] Figure 6 This is a room temperature tensile stress-strain curve of Al-La-Sc-Zr aluminum alloy rods prepared by hot extrusion in Example 2. Figure 6 It can be seen that the room temperature tensile strength of the aluminum alloy bar is 281 MPa and the elongation after fracture is 10%.

[0039] Figure 7 This is a room temperature tensile stress-strain curve of Al-La-Sc-Zr aluminum alloy rods prepared by hot extrusion in Example 2. Figure 6 It can be seen that the high-temperature tensile strength of the aluminum alloy bar is 99 MPa and the elongation after fracture is 16.7%.

[0040] Example 3 A method for preparing a heat-resistant Al-La-Sc aluminum alloy with heterogeneous bimodal grains, comprising the following steps: (1) Prepare the raw materials according to the following weight ratio: 11.50wt.%La, 0.5wt.%Sc, and the balance is Al. Melt the raw materials in a vacuum induction melting furnace, heat the molten metal to 780℃ and keep it at this temperature for 30 minutes, and then place the molten metal in a vertical four-column hydraulic press to perform extrusion casting to obtain the required ingot. (2) Use a wire cutting machine to cut out cylindrical materials of Φ30mm×30mm as blanks in areas relatively far from the edge, top and bottom of the ingot, and use coarse sandpaper to polish the surface of the blanks to remove wire cutting marks and their oxidation products; (3) The muffle furnace and hot extruder are heated to 400℃ and kept at that temperature. After the temperature stabilizes, the billet obtained by wire cutting is placed into the muffle furnace for heat preservation for 15 minutes. After heat preservation, the heated billet is quickly placed into the hot extruder for extrusion. The extrusion temperature is 400℃, the extrusion ratio is 30, and the extrusion pressure is 2000KN to obtain Al-La-Sc aluminum alloy rods.

[0041] Figure 8 This is a room temperature tensile stress-strain curve for Al-La-Sc aluminum alloy bars prepared by hot extrusion in this embodiment. Figure 8 It can be seen that the room temperature tensile strength of the aluminum alloy bar is 266 MPa and the elongation after fracture is 9.3%.

[0042] Example 4 A method for preparing a heat-resistant Al-La-Sc-Zr aluminum alloy with heterogeneous bimodal grains, comprising the following steps: (1) Prepare the raw materials according to the following weight ratio: 11.50wt.%La, 0.25wt.%Sc, 0.25wt.%Zr, with the balance being Al. Melt the raw materials in a vacuum induction melting furnace, heat the molten metal to 780℃ and hold it at this temperature for 30 minutes, and then place the molten metal in a vertical four-column hydraulic press to perform extrusion casting to obtain the required ingot. (2) Use a wire cutting machine to cut out cylindrical materials of Φ30mm×30mm as blanks in areas relatively far from the edge, top and bottom of the ingot, and use coarse sandpaper to polish the surface of the blanks to remove wire cutting marks and their oxidation products; (3) The muffle furnace and hot extruder are heated to 500℃ and held at that temperature. After the temperature stabilizes, the billet obtained by wire cutting is placed into the muffle furnace for holding for 15 minutes. After holding, the heated billet is quickly placed into the hot extruder for extrusion. The extrusion temperature is 500℃, the extrusion ratio is 30, and the extrusion pressure is 2000KN to obtain Al-La-Sc-Zr aluminum alloy rods.

[0043] Figure 9 This is a room temperature tensile stress-strain curve for Al-La-Sc-Zr aluminum alloy rods prepared by hot extrusion in this embodiment. Figure 9 It can be seen that the room temperature tensile strength of the aluminum alloy bar is 259 MPa and the elongation after fracture is 9.0%.

[0044] Example 5 A method for preparing a heat-resistant Al-La-Sc aluminum alloy with heterogeneous bimodal grains, comprising the following steps: (1) Prepare the raw materials according to the following weight ratio: 11.50wt.%La, 0.5wt.%Sc, and the balance is Al. Melt the raw materials in a vacuum induction melting furnace, heat the molten metal to 780℃ and keep it at this temperature for 30 minutes, and then place the molten metal in a vertical four-column hydraulic press to perform extrusion casting to obtain the required ingot. (2) Use a wire cutting machine to cut out cylindrical materials of Φ30mm×30mm as blanks in areas relatively far from the edge, top and bottom of the ingot, and use coarse sandpaper to polish the surface of the blanks to remove wire cutting marks and their oxidation products; (3) The muffle furnace and hot extruder are heated to 450°C and held at that temperature. After the temperature stabilizes, the billet obtained by wire cutting is placed into the muffle furnace and held for 30 minutes. After the holding time is completed, the heated billet is quickly placed into the hot extruder for extrusion. The extrusion temperature is 450°C, the extrusion ratio is 30, and the extrusion pressure is 2000KN to obtain Al-La-Sc aluminum alloy rods.

[0045] Figure 10 This is a room temperature tensile stress-strain curve for Al-La-Sc aluminum alloy bars prepared by hot extrusion in this embodiment. Figure 10 It can be seen that the room temperature tensile strength of the aluminum alloy bar is 250 MPa and the elongation after fracture is 10.1%.

[0046] Example 6 A method for preparing a heat-resistant Al-La-Sc-Zr aluminum alloy with heterogeneous bimodal grains, comprising the following steps: (1) Prepare the raw materials according to the following weight ratio: 11.50wt.%La, 0.25wt.%Sc, 0.25wt.%Zr, with the balance being Al. Melt the raw materials in a vacuum induction melting furnace, heat the molten metal to 780℃ and hold it at this temperature for 30 minutes, and then place the molten metal in a vertical four-column hydraulic press to perform extrusion casting to obtain the required ingot. (2) Use a wire cutting machine to cut out cylindrical materials of Φ30mm×30mm as blanks in areas relatively far from the edge, top and bottom of the ingot, and use coarse sandpaper to polish the surface of the blanks to remove wire cutting marks and their oxidation products; (3) The muffle furnace and hot extruder are heated to 400℃ and held at that temperature. After the temperature stabilizes, the billet obtained by wire cutting is placed into the muffle furnace for holding for 15 minutes. After holding, the heated billet is quickly placed into the hot extruder for extrusion. The extrusion temperature is 400℃, the extrusion ratio is 30, and the extrusion pressure is 2000KN to obtain Al-La-Sc-Zr aluminum alloy rods.

[0047] Figure 11This is a room temperature tensile stress-strain curve for Al-La-Sc-Zr aluminum alloy rods prepared by hot extrusion in this embodiment. Figure 11 It can be seen that the room temperature tensile strength of the aluminum alloy bar is 236 MPa and the elongation after fracture is 12.5%.

[0048] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a heat-resistant aluminum alloy with heterogeneous bimodal grains, characterized in that, Includes the following steps: (1) The raw materials are melted, impurities are removed and heat is maintained, and then the required alloy ingots are prepared by extrusion casting; (2) The alloy ingot obtained in step (1) is wire-cut into cylindrical materials as blanks; (3) Keep the blank obtained in step (2) warm, and then put it into a hot extruder for hot extrusion to obtain the heterogeneous bimodal grain heat-resistant aluminum alloy.

2. The method for preparing the heterogeneous bimodal grain heat-resistant aluminum alloy according to claim 1, characterized in that, In step (1), the rare earth aluminum alloy ingot composition is: 5~15wt.%La, 0.1~1wt.%Sc, 0~0.5wt.%Zr, with the balance being Al and unavoidable impurities.

3. The method for preparing the heterogeneous bimodal grain heat-resistant aluminum alloy according to claim 1, characterized in that, In step (1), the raw materials are pure aluminum ingots, Al-La master alloys and Al-Sc master alloys, or pure aluminum ingots, Al-La master alloys, Al-Sc master alloys and Al-Zr master alloys.

4. The method for preparing the heterogeneous bimodal grain heat-resistant aluminum alloy according to claim 1, characterized in that, In step (1), the melting temperature is 700~800℃; the holding temperature is 700~800℃, and the holding time is 10~30min.

5. The method for preparing the heterogeneous bimodal grain heat-resistant aluminum alloy according to claim 1, characterized in that, In step (2), the sampling area is relatively far from the edge, top, and bottom of the ingot.

6. The method for preparing the heterogeneous bimodal grain heat-resistant aluminum alloy according to claim 1, characterized in that, In step (3), the insulation temperature of the blank is 350~550℃ and the insulation time is 15min~30min.

7. The method for preparing the heterogeneous bimodal grain heat-resistant aluminum alloy according to claim 1, characterized in that, In step (3), the hot extrusion temperature is 350~550℃, the extrusion ratio is 10~40, and the extrusion pressure is 500~2000KN.

8. A heterogeneous bimodal grain heat-resistant aluminum alloy prepared by the preparation method according to any one of claims 1 to 7.

9. The heterogeneous bimodal grain heat-resistant aluminum alloy according to claim 8, characterized in that, The heat-resistant aluminum alloy prepared by this method has a heterogeneous bimodal grain structure with equiaxed grains embedded with fine fibrous grains. The average grain size of the equiaxed fine grains is 1.6 μm, and the average grain size of the fibrous coarse grains is 6.7 μm.

10. The heterogeneous bimodal grain heat-resistant aluminum alloy according to claim 8, characterized in that, Its room temperature tensile strength is greater than 260 MPa and its elongation after fracture is greater than 10%. Its high temperature tensile strength is greater than 100 MPa and its high temperature elongation after fracture is greater than 17%.

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