Small-angle grain boundary oxidation film based on surface layer Al-containing alloy part surface as well as preparation method and application of small-angle grain boundary oxidation film

Abstract

The invention discloses a small-angle grain boundary oxidation film based on a surface layer Al-containing alloy part surface and a preparation method and application of the small-angle grain boundary oxidation film, and belongs to the technical field of material surface modification and coating preparation. According to the method, through preferred orientation nucleation of aluminum oxide and thickening treatment of the oxidation film, grains in the obtained oxidation film have specific preferred orientation, grain boundaries between the grains are dominated by small-angle grain boundaries, internal diffusion of oxygen atoms is greatly slowed down, and therefore the high-temperature oxidation resistance of the alloy part with the surface layer containing Al is improved. The technical problem that an alloy part with the Al-contained surface layer is oxidized too fast at high temperature and fails in advance is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of material surface modification and coating preparation, and particularly relates to a small-angle grain boundary oxide film based on the surface of an Al-containing alloy part, and a preparation method and application thereof. Background Art

[0002] Metals face serious oxidation problems during high-temperature service, which can lead to disastrous consequences. However, Al-containing alloys can form α-Al2O3 oxide films at high temperatures, which can effectively hinder the internal diffusion of oxygen atoms, thereby improving the high-temperature oxidation resistance of the metal matrix.

[0003] Since grain boundaries are the main channels for the diffusion of oxygen atoms in α-Al2O3 oxide films, the current method to improve the high-temperature oxidation resistance of Al-containing alloys is to increase the grain size of aluminum oxide in the oxide film by low oxygen partial pressure pretreatment, thereby reducing the number of grain boundaries. However, this method has limited effect in improving oxidation resistance, and excessively large oxide film grain size can also lead to cracking of the oxide film, causing the oxide film to lose its antioxidant properties.

[0004] The prior art patent CN112281107A discloses a double-layer protective oxide film, in which the outer side is a continuous and dense chromium oxide film with a thickness of 3.8-6.0 μm, and the inner side is a discontinuous aluminum oxide inner oxide. However, the oxide film thickness is uneven and the grain size distribution is uneven, which significantly affects the oxidation resistance of Al-containing alloy parts at high temperatures. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a small-angle grain boundary oxide film based on the surface of Al-containing alloy parts and its preparation method and application, which solves the technical problem of Al-containing alloy parts oxidizing too quickly at high temperatures and failing prematurely.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The invention discloses a small-angle grain boundary oxide film based on the surface of a surface Al-containing alloy part. The oxide film is formed by heat treating the surface Al-containing alloy part under a certain oxygen partial pressure condition, and the surface of the surface Al-containing alloy part presents small-angle grain boundaries and a dense oxide film without through pores.

[0008] Preferably, the small-angle grain boundary oxide film is a film in which grains grow along a specific crystal direction, and the proportion of grains deviating from this direction by 0° to 15° is not less than 60%, the grain boundary angle of the oxide film does not exceed 15°, and the proportion of small-angle grain boundaries is not less than 60%; the thickness of the oxide film is 100 to 2000nm, and the grain size of the oxide film is 200 to 2000nm.

[0009] Preferably, the oxide film is prepared by heat treating the surface Al-containing alloy part in an atmosphere with an oxygen partial pressure mainly composed of argon.

[0010] The present invention also discloses a method for preparing the above-mentioned low-angle grain boundary oxide film, comprising the following steps:

[0011] 1) performing a pre-oxidation treatment of the pre-treated surface Al-containing alloy part for crystal orientation preferential nucleation until the oxide film completely covers the surface of the alloy part;

[0012] 2) The Al-containing alloy part having a surface layer that has been pre-oxidized is subjected to an oxidation film thickening treatment to obtain a small-angle grain boundary oxidation film with a certain thickness.

[0013] Preferably, the pretreatment in step 1) is fresh surface exposure treatment, which refers to the removal of the original oxide film, impurities, etc. on the surface of the material. The specific method includes but is not limited to mechanical polishing, pickling, alkali washing, etc. of the surface;

[0014] Preferably, in step 1), the pre-oxidation treatment is: placing the Al-containing alloy part in an atmosphere furnace, pumping the gas pressure in the furnace to 1Pa-5Pa, filling with high-purity argon with an oxygen content of 0.001ppm-0.02ppm, keeping it at 900℃~1200℃ for 1h~100h, and the heating and cooling rate is 1~20℃ / .

[0015] Further preferably, in step 1), the pre-oxidation treatment is: placing the surface Al-containing alloy part in an atmosphere furnace, pumping the gas pressure in the furnace to 1 Pa, filling it with high-purity argon with an oxygen content of 0.005 ppm, keeping it at 1200°C for 100h, and the heating and cooling rate is 1°C / h.

[0016] The purpose of this step is to adjust the oxygen partial pressure to be higher than the critical oxygen partial pressure for alumina nucleation and lower than the critical oxygen partial pressure for the second easiest nucleation direction of alumina. This high temperature treatment process helps the Al element on the alloy surface react with oxygen to form alumina (Al2O3) nuclei. Since the oxygen content in the atmosphere is extremely low, this process is controllable and helps to form alumina nuclei with a specific crystal orientation. The critical oxygen partial pressure for alumina nucleation refers to the minimum value of the oxygen partial pressure that can satisfy the nucleation of alumina at the current heat treatment temperature; the second easiest nucleation direction of alumina refers to the energy required for alumina to nucleate along this crystal direction, which is second only to the energy required along the easiest nucleation direction; the critical oxygen partial pressure for the second easiest nucleation direction of alumina refers to the oxygen partial pressure corresponding to the energy required for alumina to nucleate along this crystal direction at the current heat treatment temperature.

[0017] Preferably, in step 2), the oxide film thickening treatment is as follows: the gas pressure in the furnace is re-pumped to 1Pa-5Pa, filled with high-purity argon gas with an oxygen content of 20ppm-150ppm, and kept at 900℃~1200℃ for 1h~100h, with a heating and cooling rate of 1~20℃ / .

[0018] Further preferably, in step 2), the oxide film thickening treatment is as follows: the gas pressure in the furnace is pumped down to 1 Pa again, filled with high-purity argon gas with an oxygen content of 20 ppm, kept at 1200° C. for 10 h, and the heating and cooling rate is 1° C. / h.

[0019] The purpose of this step is to adjust the oxygen partial pressure to be higher than the critical oxygen partial pressure for the nucleation of aluminum oxide. This high temperature treatment process allows the aluminum oxide layer to continue to grow on the alloy surface, forming a thicker oxide film. Compared with the pre-oxidation treatment in step 1), the oxygen content is higher this time, the purpose is to accelerate the growth of the aluminum oxide layer and make it thicker.

[0020] The invention also discloses the application of the small-angle grain boundary oxide film in a surface Al-containing alloy part.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The invention discloses a small-angle grain boundary oxide film based on the surface of a surface Al-containing alloy part, and the oxide film exhibits the characteristics of small-angle grain boundaries and dense without through pores. The innovation of the invention is that under certain oxygen partial pressure conditions, the surface Al-containing alloy part is heat treated so that the oxide film formed on the surface of the surface Al-containing alloy part exhibits the characteristics of small-angle grain boundaries and dense without through pores, which greatly slows down the internal diffusion of oxygen atoms, thereby improving the high-temperature oxidation resistance of the surface Al-containing alloy part.

[0023] Furthermore, the grains of the small-angle grain boundary oxide film grow along a specific crystal direction, and the proportion of grains that deviate from this direction by 0° to 15° is not less than 60%. This structure is dense and has no through pores, which enhances the protective performance of the oxide film and helps to form a highly ordered structure, so that the grains in the obtained oxide film have a specific preferential orientation, so that the grain boundaries between the grains are dominated by small-angle grain boundaries. The grain boundary angle of the small-angle grain boundary oxide film does not exceed 15°, and the proportion of small-angle grain boundaries is not less than 60%, which makes the oxide film denser and reduces pores and defects. The grain size of the small-angle grain boundary oxide film is 200 to 2000nm, and the thickness of the small-angle grain boundary oxide film is 100 to 2000nm. These parameter characteristics ensure that the thickness of the oxide film is sufficient to provide effective protection, and the grain size is moderate, which is conducive to the formation of a uniform and dense oxide film structure.

[0024] The present invention also discloses a method for preparing a small-angle grain boundary oxide film on the surface of an Al-containing alloy part. First, the pre-treated Al-containing alloy part is subjected to a pre-oxidation treatment for crystal orientation-preferred nucleation, which helps to form an initial oxide film with alumina nuclei in a specific crystal orientation on the alloy surface. Secondly, through the oxide film thickening treatment, the growth of the aluminum oxide layer is accelerated under a higher oxygen partial pressure to make it thicker, while maintaining the characteristic of grain growth along a specific crystal orientation, thereby improving the coverage and protection of the oxide film, effectively isolating the alloy matrix from the external environment, and thus improving the high-temperature oxidation resistance of the alloy part. The two-step oxidation treatment process ensures the uniformity and density of the oxide film.

[0025] Furthermore, by placing the surface Al-containing alloy part in an atmosphere furnace, pumping the furnace pressure to 1Pa-5Pa, filling with high-purity argon gas with an oxygen content of 0.001ppm-0.02ppm, pre-oxidation treatment at 900℃-1200℃ for 1-100h, and heating and cooling at a rate of 1-20℃ / h, the oxygen partial pressure is adjusted to be higher than the critical oxygen partial pressure of alumina nucleation and lower than the critical oxygen partial pressure of the second most nucleation direction of alumina. Such oxygen partial pressure conditions help to induce alumina grains to preferentially nucleate in a specific direction, so that alumina in other directions does not nucleate, thereby achieving a preferred orientation, so as to ensure that the alumina grains can nucleate and grow according to the predetermined preferred orientation. The key to this step is to accurately control the oxygen partial pressure and heat treatment conditions so that the grains in the obtained oxide film have a specific preferred orientation, so that the grain boundaries between the grains are dominated by small-angle grain boundaries, which greatly slows down the internal diffusion of oxygen atoms and improves the high-temperature oxidation resistance of the surface Al-containing alloy part.

[0026] Furthermore, by placing the surface Al-containing alloy parts in an atmosphere furnace, pumping the furnace pressure to 1-5Pa, filling with high-purity argon with an oxygen content of 20-150ppm, keeping at 900℃~1200℃ for 1~100h, and performing an oxide film thickening treatment with a heating and cooling rate of 1-20℃ / h, the oxygen partial pressure is adjusted to be higher than the critical oxygen partial pressure of alumina nucleation, so as to promote the aluminum oxide layer to continue to grow and thicken on the alloy surface. The oxygen partial pressure in this step is higher, but it still needs to be maintained at a level higher than the critical oxygen partial pressure of alumina nucleation. The purpose of this step is to accelerate the growth rate of the aluminum oxide layer to obtain an oxide film of the desired thickness, so that the oxide film can better block the corrosion of oxygen and other corrosive substances in the external environment to the Al-containing alloy parts, thereby significantly improving the high-temperature oxidation resistance of the alloy parts. In summary, the small-angle grain boundary oxide film in the preparation method of the present application solves the technical problem that Al-containing alloy parts oxidize too quickly at high temperatures and fail prematurely. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a surface Al-containing alloy part having a surface low-angle grain boundary oxide film according to the present invention;

[0028] Figure 2 This is a surface EBSD characterization result diagram of the small-angle grain boundary oxide film of the present invention;

[0029] Figure 3 It is a graph showing the proportion of grain boundaries at different angles of the small-angle grain boundary oxide film of the present invention;

[0030] Figure 4 This is a fractured surface morphology of the oxide film of the surface Al-containing alloy part that has not been pre-oxidized and has not been treated with oxide film thickening.

[0031] Figure 5 This is the fracture surface morphology of the oxide film of the surface Al-containing alloy part that has undergone pre-oxidation treatment and oxide film thickening treatment. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0033] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0034] The present invention is described in further detail below in conjunction with embodiments:

[0035] Example 1

[0036] The method for preparing a small-angle grain boundary oxide film using a surface Al-containing alloy part as a substrate comprises the following steps:

[0037] 1) Fresh surface exposure treatment of Al alloy parts on the surface: Use 200-2000 mesh sandpaper to grind the Al alloy parts on the surface, then use 0.5 μm diamond polishing agent to polish the Al alloy parts on the surface, and then use deionized water to clean the Al alloy parts on the surface;

[0038] 2) Pre-oxidation treatment for preferential nucleation in crystal orientation: Place the Al-containing alloy parts on the surface in an atmosphere furnace, and pump the furnace pressure to 1Pa to remove the air and other impurities in the furnace to ensure that subsequent treatment is carried out in a pure environment. Fill with high-purity argon gas with an oxygen content of 0.005ppm. High-purity argon gas is used as the main atmosphere here, and a very small amount of oxygen is added to initiate and control the oxidation reaction on the alloy surface. Keep the temperature at 1200℃ for 10h, and the heating and cooling speed is 1℃ / h. The speed control here ensures that the alloy parts will not produce thermal stress or cracks due to excessively rapid temperature changes during heating and cooling;

[0039] 3) Oxide film thickening treatment: The furnace pressure was pumped down to 1Pa to ensure that the subsequent treatment was carried out in a pure environment. High-purity argon gas with an oxygen content of 20ppm was filled and kept at 1200℃ for 10h. The heating and cooling rate was 1℃ / h to ensure the stability of the alloy during heating and cooling. A dense aluminum oxide film with small-angle grain boundary characteristics was obtained. The oxide film thickness was 2000nm. Figure 2 The EBSD characterization results of the oxide film surface show that its grain size is about 600nm, with obvious

[0001] crystal phase preference. Figure 3 is the proportion of grain boundaries at different angles. It can be seen that small-angle grain boundaries account for about 72%.

[0040] The Al-containing alloy parts with a surface layer that had not been subjected to pre-oxidation treatment and oxide film thickening treatment and the Al-containing alloy parts with a surface layer that had been subjected to pre-oxidation treatment and oxide film thickening treatment in Example 1 were subjected to a high-temperature oxidation test at 1200°C for 100 hours. Figure 4 This is the fracture morphology of the oxide film of the Al-containing alloy part without pre-oxidation treatment and oxide film thickening treatment. Figure 5 This is a cross-sectional morphology of the oxide film of a surface Al-containing alloy part that has undergone pre-oxidation treatment and oxide film thickening treatment. Figure 4 and Figure 5 It can be seen that the thickness of the oxide film after pre-oxidation treatment and oxide film thickening treatment is significantly reduced by about 89 times, which significantly slows down its oxidation rate. In addition, the oxide film is a continuous aluminum oxide film, which further protects the surface Al-containing alloy matrix and improves the high-temperature oxidation resistance of the alloy part.

[0041] Example 2

[0042] The method for preparing a small-angle grain boundary oxide film using a surface Al-containing alloy part as a substrate comprises the following steps:

[0043] 1) Fresh surface exposure treatment of Al alloy parts on the surface: Use 200-2000 mesh sandpaper to grind the Al alloy parts on the surface, then use 0.5 μm diamond polishing agent to polish the Al alloy parts on the surface, and then use deionized water to clean the Al alloy parts on the surface;

[0044] 2) Pre-oxidation treatment for preferential nucleation of crystal orientation: Place the Al-containing alloy part on the surface in an atmosphere furnace, pump the pressure in the furnace to 5 Pa, fill it with high-purity argon gas with an oxygen content of 0.02 ppm, keep it at 1000°C for 20 hours, and the heating and cooling rate is 10°C / h;

[0045] 3) Oxide film thickening treatment: The gas pressure in the furnace was re-evacuated to 2Pa, filled with high-purity argon with an oxygen content of 75ppm, and kept at 1000℃ for 10h with a heating and cooling rate of 10℃ / h to obtain a dense aluminum oxide film with small-angle grain boundary characteristics. The oxide film was 1000nm thick, the grain size was 800nm, and the small-angle grain boundary accounted for 69%. The oxide film slowed down the oxidation rate of the surface Al-containing alloy parts at 1000℃ by 70 times.

[0046] Example 3

[0047] The method for preparing a small-angle grain boundary oxide film using a surface Al-containing alloy part as a substrate comprises the following steps:

[0048] 1) Fresh surface exposure treatment of Al alloy parts on the surface: Use 200-2000 mesh sandpaper to grind the Al alloy parts on the surface, then use 0.5 μm diamond polishing agent to polish the Al alloy parts on the surface, and then use deionized water to clean the Al alloy parts on the surface;

[0049] 2) Pre-oxidation treatment for preferential nucleation of crystal orientation: Place the Al-containing alloy part on the surface in an atmosphere furnace, pump the pressure in the furnace to 5 Pa, fill it with high-purity argon gas with an oxygen content of 0.001 ppm, keep it at 1150°C for 15 hours, and the heating and cooling rate is 20°C / h;

[0050] 3) Oxide film thickening treatment: The gas pressure in the furnace was re-evacuated to 5Pa, filled with high-purity argon with an oxygen content of 150ppm, and kept at 1150℃ for 5h with a heating and cooling rate of 20℃ / h to obtain a dense aluminum oxide film with small-angle grain boundary characteristics. The oxide film was 800nm ​​thick, the grain size was 500nm, and the small-angle grain boundary accounted for 77%. The oxide film slowed down the oxidation rate of the surface Al-containing alloy parts at 1150℃ by 74 times.

[0051] Example 4

[0052] The method for preparing a small-angle grain boundary oxide film using a surface Al-containing alloy part as a substrate comprises the following steps:

[0053] 1) Fresh surface exposure treatment of Al alloy parts on the surface: Use 200-2000 mesh sandpaper to grind the Al alloy parts on the surface, then use 0.5 μm diamond polishing agent to polish the Al alloy parts on the surface, and then use deionized water to clean the Al alloy parts on the surface;

[0054] 2) Pre-oxidation treatment for preferential nucleation of crystal orientation: Place the Al-containing alloy part on the surface in an atmosphere furnace, pump the pressure in the furnace to 2 Pa, fill it with high-purity argon gas with an oxygen content of 0.003 ppm, keep it at 900°C for 1 hour, and the heating and cooling rate is 10°C / h;

[0055] 3) Oxide film thickening treatment: The gas pressure in the furnace was re-evacuated to 2Pa, filled with high-purity argon with an oxygen content of 40ppm, and kept at 900℃ for 1h. The heating and cooling rates were 10℃ / h, and a dense aluminum oxide film with small-angle grain boundary characteristics was obtained. The oxide film was 100nm thick, the grain size was 200nm, and the small-angle grain boundaries accounted for 62%. The oxide film slowed down the oxidation rate of the surface Al-containing alloy parts at 900℃ by 39 times.

[0056] Example 5

[0057] The method for preparing a small-angle grain boundary oxide film using a surface Al-containing alloy part as a substrate comprises the following steps:

[0058] 1) Fresh surface exposure treatment of Al alloy parts on the surface: Use 200-2000 mesh sandpaper to grind the Al alloy parts on the surface, then use 0.5 μm diamond polishing agent to polish the Al alloy parts on the surface, and then use deionized water to clean the Al alloy parts on the surface;

[0059] 2) Pre-oxidation treatment for preferential nucleation of crystal orientation: Place the Al-containing alloy part on the surface in an atmosphere furnace, pump the furnace pressure to 3 Pa, fill with high-purity argon gas with an oxygen content of 0.003 ppm, keep the temperature at 900°C for 50.5 hours, and the heating and cooling speed is 10°C / h;

[0060] 3) Oxide film thickening treatment: The gas pressure in the furnace was re-evacuated to 3Pa, filled with high-purity argon with an oxygen content of 80ppm, and kept at 1150℃ for 50.5h, with a heating and cooling rate of 10℃ / h, to obtain a dense aluminum oxide film with small-angle grain boundary characteristics. The oxide film was 300nm thick, with a grain size of 200nm, and small-angle grain boundaries accounted for 75%. The oxide film slowed down the oxidation rate of the surface Al-containing alloy parts at 1150℃ by 55 times.

[0061] Example 6

[0062] The method for preparing a small-angle grain boundary oxide film using a surface Al-containing alloy part as a substrate comprises the following steps:

[0063] 1) Fresh surface exposure treatment of Al alloy parts on the surface: Use 200-2000 mesh sandpaper to grind the Al alloy parts on the surface, then use 0.5 μm diamond polishing agent to polish the Al alloy parts on the surface, and then use deionized water to clean the Al alloy parts on the surface;

[0064] 2) Pre-oxidation treatment for preferential nucleation of crystal orientation: Place the Al-containing alloy part on the surface in an atmosphere furnace, pump the furnace pressure to 4 Pa, fill with high-purity argon gas with an oxygen content of 0.005 ppm, keep the temperature at 900°C for 100h, and the heating and cooling rate is 10°C / h;

[0065] 3) Oxide film thickening treatment: The gas pressure in the furnace was re-evacuated to 4Pa, filled with high-purity argon with an oxygen content of 122.5ppm, and kept at 1150℃ for 100h, with a heating and cooling rate of 10℃ / h, to obtain a dense aluminum oxide film with small-angle grain boundary characteristics. The oxide film was 100nm thick, with a grain size of 500nm, and small-angle grain boundaries accounted for 80%. The oxide film slowed down the oxidation rate of the surface Al-containing alloy parts at 1150℃ by 45 times.

[0066] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A low-angle grain boundary oxide film on the surface of an Al-containing alloy part, characterized in that: The oxide film is formed by heat treating the surface Al-containing alloy parts under certain oxygen partial pressure conditions, and the surface Al-containing alloy parts show small-angle grain boundaries and dense oxide film without through pores.

2. The low-angle grain boundary oxide film on the surface of the Al-containing alloy part according to claim 1, characterized in that: The small-angle grain boundary oxide film is a grain that grows along a specific crystal direction, and the proportion of grains that deviate from this direction by 0° to 15° is not less than 60%. The grain boundary angle of the oxide film does not exceed 15°, and the proportion of small-angle grain boundaries is not less than 60%; the thickness of the oxide film is 100 to 2000nm, and the grain size of the oxide film is 200 to 2000nm.

3. The low-angle grain boundary oxide film on the surface of the Al-containing alloy part according to claim 1, characterized in that: The oxide film is prepared by heat treating the surface Al-containing alloy part in an atmosphere with an oxygen partial pressure mainly composed of argon.

4. A method for preparing a low-angle grain boundary oxide film on the surface of an Al-containing alloy part according to any one of claims 1 to 3, characterized in that: The following steps are involved: 1) performing a pre-oxidation treatment of the pre-treated surface Al-containing alloy part for crystal orientation preferential nucleation until the oxide film completely covers the surface of the alloy part; 2) The Al-containing alloy part having a surface layer that has been pre-oxidized is subjected to an oxidation film thickening treatment to obtain a small-angle grain boundary oxidation film with a certain thickness.

5. The method for preparing a low-angle grain boundary oxide film on the surface of an Al-containing alloy part according to claim 4, characterized in that: In step 1), the pre-oxidation treatment is as follows: placing the surface Al alloy part in an atmosphere furnace, pumping the gas pressure in the furnace to 1Pa-5Pa, filling with high-purity argon gas with an oxygen content of 0.001ppm-0.02ppm, keeping it at 900℃~1200℃ for 1h~100h, and the heating and cooling rate is 1~20℃ / h.

6. The method for preparing a low-angle grain boundary oxide film on the surface of an Al-containing alloy part according to claim 5, characterized in that: In step 1), the pre-oxidation treatment is as follows: the surface Al alloy part is placed in an atmosphere furnace, the gas pressure in the furnace is pumped down to 1 Pa, high-purity argon gas with an oxygen content of 0.005 ppm is filled, and the temperature is kept at 1200°C for 100 hours, with a heating and cooling rate of 1°C / h.

7. The method for preparing a low-angle grain boundary oxide film on the surface of an Al-containing alloy part according to claim 4, characterized in that: In step 2), the oxide film thickening treatment is as follows: the gas pressure in the furnace is pumped back to 1Pa-5Pa, filled with high-purity argon gas with an oxygen content of 20ppm-150ppm, and kept at 900℃~1200℃ for 1h~100h, with a heating and cooling rate of 1~20℃ / h.

8. The method for preparing a low-angle grain boundary oxide film on the surface of an Al-containing alloy part according to claim 7, characterized in that: In step 2), the oxide film thickening treatment is as follows: the gas pressure in the furnace is pumped down to 1 Pa again, filled with high-purity argon gas with an oxygen content of 20 ppm, kept at 1200° C. for 10 h, and the heating and cooling rate is 1° C. / h.

9. The method for preparing a low-angle grain boundary oxide film on the surface of an Al-containing alloy part according to claim 4, characterized in that: In step 1), the pretreatment includes: performing fresh surface exposure treatment on the surface Al-containing alloy part.

10. Use of the small-angle grain boundary oxide film according to any one of claims 1 to 3 in a surface Al-containing alloy part.

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