A method for improving the corrosion resistance of Al-Cu-Li alloy by composite ion implantation

Abstract

The present invention discloses a method for improving the corrosion resistance of an Al-Cu-Li alloy by composite ion implantation, comprising: performing thermoplastic deformation on the Al-Cu-Li alloy and pre-treating its surface, and then simultaneously implanting composite Zr, Ti, Zn, and Cr ions, wherein the Zr / Ti ion ratio is 1 to 3:1, and the Zn / Cr ion ratio is 1.5 to 2.5:1. The present invention uses composite Zr, Ti, Zn, and Cr ion implantation to ensure the stability of the alloy surface modification layer, improve the alloy hardness and wear resistance, and simultaneously improve the corrosion resistance and fatigue resistance of the permeation layer; the ion penetration depth is increased, avoiding the disadvantage of damage to the modified layer caused by a too-thin coating, further improving the hardness, wear resistance, and fatigue limit of the alloy; inhibiting matrix recrystallization, reducing the potential difference within the alloy grains and between the grain boundaries, and significantly improving the corrosion resistance of the alloy.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal surface strengthening and relates to a method for improving the corrosion resistance of an Al-Cu-Li alloy by composite ion implantation. The method is used to promote the application of high-strength, corrosion-resistant extruded aluminum-lithium alloys in the aerospace field and to improve the application rate and service life of the extruded aluminum-lithium alloys. Background Art

[0002] Aluminum-lithium alloy is one of the most promising structural materials in the aerospace field. Al-Cu-Li alloy has a wide range of applications in the field of lightweight aerospace, such as fuselage chords, fuselage frames, pillars, floor beams, etc. due to its low density, high elastic modulus and high strength. However, due to the low hardness of aluminum-lithium alloy and the presence of amorphous and extremely thin natural oxide film naturally formed on its surface, its wear resistance and corrosion resistance are not high, thus limiting the wide application of aluminum-lithium alloy in various industrial fields. Therefore, in order to adapt to long-term harsh and severe service environment and expand the application field of aluminum-lithium alloy, surface modification is a common method to obtain high strength, high corrosion resistance, high wear resistance and fatigue life of aluminum-lithium alloy without reducing the performance of the aluminum-lithium alloy matrix material itself.

[0003] Ion implantation has been increasingly used as a surface modification technique for aluminum-lithium alloys. Ion implantation involves ionizing the target element in an ion source system and then introducing the resulting positive ions into an accelerating electric field for acceleration. The ions, accelerated to a high energy (0-100 kV), are then introduced into a working target system and implanted onto the target material surface, ultimately improving the material's surface properties. Ion implantation is an unbalanced process, and the implanted element is not subject to metallurgical constraints. There is no clear boundary between the implanted layer and the substrate, resulting in a high degree of bonding. The implantation process allows for precise control of the implanted element, dose, and depth. Furthermore, the implantation process is performed in a vacuum environment, minimizing environmental pollution. The paper "Improving the Wear and Corrosion Resistance of 2195 Al-Li Alloy by Nitrogen Ion Implantation" (Plating and Finishing, 2022, Vol. 44, No. 11, pp. 6-11) reports that the implantation of nitrogen ions into 2195 aluminum-lithium alloy forms a new AlN phase on the alloy surface, improving the alloy's corrosion resistance. However, dynamic recrystallization and texture transformation during the nitrogen implantation process can soften the alloy surface and reduce its hardness. Patent CN 112609068 B (A composite strengthening method for improving stress corrosion resistance of light alloys) discloses a composite strengthening method for improving stress corrosion resistance of light alloys. The method develops a composite strengthening process for stress corrosion resistance by combining pulsed magnetic field, deep cold laser shot peening, Cu ion implantation and surface rolling strengthening, thereby improving stress corrosion resistance of light alloys. However, the method injects Cu elements with a higher potential than the alloy matrix into the light alloy, which may promote anodic dissolution of the matrix and reduce the corrosion resistance of the alloy. In addition, the process is relatively complicated, the alloy preparation cost is high, and it is not suitable for large-scale production. The literature Corrosion resistance properties of AZ31 magnesium alloy after Ti ion implantation (Rare Metals 26 (2) 2007 142-146) reports a method of implanting Ti ions into the surface of AZ31 magnesium alloy to improve corrosion resistance. However, the outermost surface is usually a mixture of metal Ti and metal Mg, which will form a galvanic couple in the corrosive medium. Mg acts as an anode and accelerates corrosion. Therefore, the penetration depth of a single ion implantation on the material surface is generally only 100 to 500 nm. If the coating is too thin, the modified layer will be completely damaged, and the bonding strength between the modified layer and the substrate will also affect whether the modified layer can provide effective protection for the substrate. At the same time, choosing the right ion species to penetrate into the aluminum-lithium alloy is also a key issue restricting the alloy's ability to improve corrosion resistance.

[0004] To address the above problems, patent CN 115652272 A (A N and Cu ion-implanted titanium alloy modified coating, its preparation method and application) discloses a N and Cu ion-implanted titanium alloy modified coating, its preparation method and application. This method uses the sequential injection of N and Cu ions and performs chemical copper plating on the surface to obtain a soft and hard two-phase composite coating. This method solves the shortcomings of the single ion injection penetrating the alloy surface too thinly and the alloy surface performance will be greatly reduced once the coating is destroyed, thereby improving the wear resistance of the alloy. However, the soft and hard two-phase composite layer may have the problem of low bonding strength, and the chemical copper plating method is costly and environmentally harmful, making it unsuitable for large-scale application. Patent CN 109267029B (A method for preparing a magnesium alloy surface coating with high flatness, high wear resistance, and high corrosion resistance) discloses a method for preparing a magnesium alloy surface coating with high flatness, high wear resistance, and high corrosion resistance. This method uses N and Cr dual ion implantation to generate a CrN phase on the alloy surface, addressing the problem of existing Mg alloy surface coatings that suffer from excessive roughness, resulting in low bonding strength, wear resistance, and low corrosion resistance. However, once the wear-modified layer is destroyed, the Mg alloy substrate, due to its relatively negative potential, forms a micro-galvanic couple with the Cr element in the penetration layer, causing corrosion. Therefore, the key is to improve the stability of the alloy surface modification layer while also enhancing the corrosion resistance of the penetration layer.

[0005] In summary, ion implantation surface treatment is an effective method to improve the corrosion resistance of aluminum-lithium alloys. However, the implantation of a single ion has the disadvantages of a too thin modified film layer and poor stability. Although the method of combining ion implantation with other metal surface strengthening processes has improved the surface properties of aluminum-lithium alloys, the related processes may be more complicated, and the bonding strength between the coating and the substrate will also affect the service life of the alloy. Therefore, while ensuring that the modified layer of the ion implantation has good stability and good bonding strength with the substrate to improve the hardness and wear resistance of the alloy, it is also required that the ions penetrating into the alloy matrix refine the grains and inhibit crack initiation, and that the new phases produced by penetrating into the matrix are not prone to galvanic corrosion with the matrix. Therefore, it is crucial to invent an ion implantation strengthening process that can improve the surface properties of aluminum-lithium alloys, improve corrosion resistance and fatigue resistance, and has a relatively simple process. Summary of the Invention

[0006] In response to the above-mentioned deficiencies in the prior art, the present invention provides a method for improving the corrosion resistance of Al-Cu-Li alloys by composite ion implantation, which enables the deformed Al-Cu-Li alloy to obtain high corrosion resistance, wear resistance, hardness and a longer fatigue life, while also improving the stability of the alloy surface modification layer and its bonding strength with the substrate, thereby extending the service life of the alloy and shortening the alloy preparation process.

[0007] In order to achieve the above-mentioned technical effects, the present invention proposes a new method for improving the corrosion resistance, wear resistance, hardness and fatigue resistance of deformed Al-Cu-Li alloy by ion implantation, which is significantly different from the existing ion implantation method of aluminum-lithium alloy. The existing ion implantation method of aluminum-lithium alloy has the disadvantages of too thin penetration layer, poor stability and exposure of the matrix once the modified layer is worn by the implantation of single elements such as N, Cu, Ti. At the same time, the injected elements cannot fundamentally change the corrosion resistance of the matrix. Although the alloy performance can be improved by combining single metal ion implantation with other metal surface strengthening processes, the galvanic corrosion caused by the potential difference between the injected metal ions and the matrix is not taken into account. At the same time, there are also problems such as unstable bonding of the modified layer and complicated preparation process. The present invention innovatively adopts a method of multiple ion composite implantation to simultaneously compositely implant Zr, Ti, Zn, and Cr ions with a potential close to that of Al into the alloy surface. This method targets the characteristics of Al-Cu-Li alloys. Since Ti atoms and Zr atoms can replace each other to form Al3 (Zr, Ti) phase, the potential difference between the phase and the matrix is small, which can reduce the sensitivity to galvanic corrosion; reduce the mismatch between the precipitated phase and the matrix, so for alloys implanted with Ti ions alone, the composite addition of Zr ions can greatly improve the strengthening effect and fatigue life of the alloy, inhibit crack initiation and improve the alloy's resistance to stress corrosion; the addition of Zn and Cr elements, since Zn can replace T1 phase, The (Al2(Cu,Zn)Li) phase is formed at the position of Cu in the precipitate phase, the content of inactive element Cu in the precipitate phase is reduced, and the potential of the T1 phase is changed. At the same time, the Cr element will form an Al-Cr-Mn phase with a potential close to that of the matrix, reducing the precipitation of the high-potential Al-Cu-Mn phase in the alloy and reducing the galvanic corrosion sensitivity between it and the matrix. Therefore, on the basis of the addition of Zr and Ti ions, the addition of Zn and Cr ions can greatly reduce the mismatch between the precipitate phase and the matrix, promote the stability of the Al3Zr phase with Li2 structure, and improve the corrosion resistance of the alloy, thereby improving the shortcomings of high corrosion sensitivity of the alloy penetration layer and instability of the modified layer when Ti ions and Cr ions are added alone.

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

[0009] In a first aspect, the present invention provides a method for improving the corrosion resistance of an Al-Cu-Li alloy by composite ion implantation, wherein Zr, Ti, Zn, and Cr ions are compositely implanted into the Al-Cu-Li alloy, wherein the Zr / Ti ion implantation dosage ratio is 1 to 3:1, and the Zn / Cr ion implantation dosage ratio is 1.5 to 2.5:1.

[0010] As an embodiment of the present invention, the Zr ion implantation dose is 1.5×10 17 ~3×10 17ions·cm 2 The implantation dose of Ti ions is 0.5×10 17 ~3×10 17 ions·cm 2 The Zn ion implantation dose is 1×10 17 ~3×10 17 ions·cm 2 The Cr ion implantation dose is 0.4×10 17 ~2×10 17 ions·cm 2 .

[0011] In the present invention, the Zr / Ti ion implantation ratio is set to 1-3:1, the Zn / Cr ion implantation ratio is set to 1.5-2.5:1, and the Zr ion implantation dose is 1.5×10 17 ~3×10 17 ions·cm 2 The implantation dose of Ti ions is 0.5×10 17 ~3×10 17 ions·cm 2 The Zn ion implantation dose is 1×10 17 ~3×10 17 ions·cm 2 The Cr ion implantation dose is 0.4×10 17 ~2×10 17 ions·cm 2 This is because in addition to controlling the formation of stable phases of various elements in the penetration layer to regulate the alloy properties, the ion implantation dose is controlled to raise the surface temperature of the sample to 200-400°C, eliminating the internal stress caused by ion implantation, making the composition and structure uniform, reducing the segregation of solute atoms at the grain boundaries, and repairing the various defects caused by high-energy ion implantation to a certain extent, so that the sample has good corrosion resistance; at the same time, it avoids the problem of uncoordinated deformation between the surface modification layer and the substrate when the single ion implantation alloy is subjected to vertical load, which easily causes the modification layer to crack.

[0012] As an embodiment of the present invention, the purity of the ions is greater than 99.9%.

[0013] As an embodiment of the present invention, the method comprises the following steps:

[0014] S1: subjecting Al-Cu-Li alloy to thermoplastic deformation treatment;

[0015] S2: pretreating the surface of the deformed Al-Cu-Li alloy obtained in S1;

[0016] S3: Composite injection of Zr, Ti, Zn, and Cr ions into the deformed Al-Cu-Li alloy after the S2 treatment to obtain a composite Al-Cu-Li alloy material.

[0017] As an embodiment of the present invention, in step S1, the thermoplastic deformation treatment includes extrusion deformation treatment of the Al-Cu-Li alloy, the extrusion temperature is 400°C to 500°C, and the extrusion ratio is 4 to 25:1.

[0018] In the present invention, since the existence radius of Zr, Ti, Zn, and Cr atoms is relatively large, it is difficult for them to diffuse on the alloy surface, resulting in a shallow penetration layer and poor bonding between the modified layer and the substrate. Therefore, by extrusion deformation treatment of the Al-Cu-Li alloy, a large number of defects such as subgrain boundaries and dislocations are generated in the alloy, which further promotes the transformation of the ordinary diffusion of ions in the alloy into short-range diffusion, thereby obtaining a certain penetration depth, achieving the purpose of optimizing the penetration layer depth and stabilizing the modified layer.

[0019] As an embodiment of the present invention, in step S2, the pretreatment includes: grinding the surface of the deformed Al-Cu-Li alloy, polishing the alloy with a polishing liquid, ultrasonically cleaning the alloy, and finally sputtering cleaning the alloy with argon.

[0020] In one embodiment of the present invention, the polishing method includes polishing the alloy surface sequentially using 300-mesh, 1200-mesh, 3000-mesh, and 7000-mesh sandpaper. After polishing until the alloy surface is smooth and free of obvious scratches, polishing with a polishing liquid until the alloy surface roughness is less than 0.5 μm.

[0021] As an embodiment of the present invention, the ultrasonic cleaning method comprises: ultrasonically cleaning the alloy with acetone and anhydrous ethanol for 10 to 20 minutes respectively.

[0022] As an embodiment of the present invention, the argon gas flow rate of the argon sputtering cleaning is 30 to 50 sccm, and the working pressure is 2.0×10 -1 ~8.0×10 -1 Pa, processing time is 10 to 20 minutes.

[0023] As an embodiment of the present invention, in step S3, the composite injection environment is vacuum, and the vacuum degree is 1.5×10 -4 ~4×10 -4 Pa.

[0024] As an embodiment of the present invention, in step S3, the acceleration voltage of the composite injection is 40-70 kV, the beam current is 0.1 mA, and the injection time is 0.5-2.5 h.

[0025] In a second aspect, the present invention provides a composite Al-Cu-Li alloy material prepared by the method.

[0026] The present invention proposes a method for improving the corrosion resistance of deformed Al-Cu-Li alloy by composite ion implantation. The strengthening of ion implantation is mainly divided into two aspects: radiation damage strengthening and grain refinement. Radiation damage strengthening is mainly because during the ion implantation process, ions collide with matrix atoms, and radiation damage zones are generated inside the impacted area. The arrangement order of the lattice atoms inside the area changes and dislocations multiply, causing the surface to harden and the hardness to be improved. In terms of grain refinement, it is mainly because high-energy implanted ions bombard the alloy surface, causing the surface microstructure to change. When the grains are finer and the surface energy of the grains is greater, under the same external load conditions, more energy consumption is required for fatigue fracture, the more obvious the hindering effect of the grain boundary is, the slower the crack propagation is, and the fatigue life of the alloy is improved; at the same time, the implantation of composite ions will also increase the penetration depth and thickness of the passivation film, reduce the potential difference between the matrix and the intermetallic compound, and reduce the corrosion sensitivity of the alloy.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention adopts a method of composite injection of Zr, Ti, Zn and Cr ions into deformed Al-Cu-Li alloy. Compared with the existing invention, the present invention improves the corrosion resistance and fatigue resistance of the penetration layer while ensuring the stability of the alloy surface modification layer and improving the alloy hardness and wear resistance; improves the penetration depth of the ions, avoids the disadvantage of the modification layer being damaged due to the coating being too thin, and further improves the hardness, wear resistance and fatigue limit of the alloy; inhibits matrix recrystallization, reduces the potential difference between the alloy grains and the grain boundaries, and significantly improves the corrosion resistance of the alloy.

[0029] (2) The deformed Al-Cu-Li alloy material provided by the present invention has excellent comprehensive performance while ensuring a low alloy preparation cost, and can achieve high hardness, high wear resistance, fatigue resistance and high corrosion resistance; the alloy hardness reaches 1500HV, which is 7.5 times higher than that of the alloy without ion implantation; the friction coefficient reaches below 0.15, and the fatigue limit strength reaches 500Mpa, which is 2.5 times higher than that of the alloy without ion implantation; the corrosion potential E SCE Below -0.60V, the intergranular corrosion resistance level is level 1, the exfoliation corrosion level is above level EA, and the stress corrosion sensitivity is I SSRT Less than 5.0%.

[0030] (3) Compared with the prior art which uses casting metallurgy to add ions to the alloy, which has the defect of agglomeration of precipitated phases and makes them easily become crack sources, the present invention uses surface ion implantation to perform composite implantation of Zr, Ti, Zn and Cr ions on the alloy after heat treatment, which is a surface strengthening treatment for the alloy and avoids technical problems such as stress concentration caused by precipitated phases becoming crack sources.

[0031] (4) The deformed Al-Cu-Li alloy profile provided by the present invention can be used in applications such as aircraft wings, fuselage frames, floor beams, seat rails, etc., and has important reference value for the development of deformation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0033] Figure 1 This is the polarization curve diagram of the electrochemical test in Example 1. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The following examples are implemented under the premise of the technical solution of the present invention, provide detailed implementation methods and specific operating procedures, and will help those skilled in the art to further understand the present invention. It should be pointed out that the scope of protection of the present invention is not limited to the following embodiments, and a number of adjustments and improvements made under the premise of the concept of the present invention all fall within the scope of protection of the present invention.

[0035] It should be noted that the polishing liquid used in the following examples and comparative examples is a MgO particle polishing liquid.

[0036] Example 1

[0037] A method for improving the corrosion resistance of an Al-Cu-Li alloy by composite ion implantation comprises the following steps:

[0038] The alloy was subjected to extrusion deformation treatment at an extrusion temperature of 400 °C and an extrusion ratio of 4:1. The surface of the alloy was then ground, polished, and polished in sequence until the surface roughness of the alloy was less than 0.5 μm. It was then ultrasonically cleaned with acetone and anhydrous ethanol for 10 min respectively and placed in a vacuum drying oven for later use. It was then sputtered and cleaned with argon gas at a gas flow rate of 30 sccm and a working pressure of 2.0×10 -1 Pa, the treatment time is 10min, and then the surface of the alloy sample is simultaneously implanted with Zr, Ti, Zn, and Cr ions. The implantation ratio of Zr / Ti ions is 1, and the implantation ratio of Zn / Cr ions is 1.5. The implantation dose of Zr ions is 1.5×10 17 ions·cm2 The Zn ion implantation dose is 1.5×10 17 ions·cm 2 The purity of the ion source is greater than 99.9%. The environmental vacuum is 3×10 -4 Pa, the accelerating voltage of ion implantation is 40 kV, the beam current is 0.1 mA, and the implantation time is 1 h.

[0039] The performance test of the obtained alloy showed that the hardness of the alloy was 1560HV by Vickers hardness test, and the wear rate of the substrate was 15.51*10 -14 mm 3 / N·mm, friction coefficient is 0.149, ultimate fatigue strength is 457MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The V is -0.537, the maximum depth of intergranular corrosion is 37.4 μm, and the exfoliation corrosion grade is above PA grade. The stress corrosion sensitivity of the alloy in a corrosion environment at 35 ° C is I SSRT =4.87%. The polarization curve of the electrochemical test is shown in the figure below. Figure 1 shown.

[0040] Example 2

[0041] A method for improving the corrosion resistance of an Al-Cu-Li alloy by composite ion implantation comprises the following steps:

[0042] The alloy was subjected to extrusion deformation treatment at an extrusion temperature of 450 °C and an extrusion ratio of 16:1. The surface of the alloy was then ground, polished, and polished in sequence until the surface roughness of the alloy was less than 0.5 μm. It was then ultrasonically cleaned with acetone and anhydrous ethanol for 20 min respectively and placed in a vacuum drying oven for later use. It was then sputtered and cleaned with argon gas at a gas flow rate of 40 sccm and a working pressure of 6.0×10 -1 Pa, the treatment time is 15min, and then the surface of the alloy sample is simultaneously implanted with Zr, Ti, Zn, and Cr ions. The implantation ratio of Zr / Ti ions is 2, and the implantation ratio of Zn / Cr ions is 2. The implantation dose of Zr ions is 2.5×10 17 ions·cm 2 The Zn ion implantation dose is 2×10 17 ions·cm 2 The purity of the ion source is greater than 99.9%. The environmental vacuum is 4×10 -4 Pa, the accelerating voltage of ion implantation is 70 kV, the beam current is 0.1 mA, and the implantation time is 1.5 h.

[0043] The performance test of the obtained alloy showed that the hardness of the alloy was 1780HV by Vickers hardness test, and the wear rate of the matrix was 12.89*10 -14 mm 3 / N·mm, friction coefficient is 0.132, ultimate fatigue strength is 554MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The V is -0.519V, the maximum depth of intergranular corrosion is 25.6μm, and the exfoliation corrosion grade is above PA grade. The stress corrosion sensitivity of the alloy in a corrosion environment at 35℃ is I SSRT =4.06%.

[0044] Example 3

[0045] A method for improving the corrosion resistance of an Al-Cu-Li alloy by composite ion implantation comprises the following steps:

[0046] The alloy was subjected to extrusion deformation treatment at an extrusion temperature of 500 ° C and an extrusion ratio of 8:1. The surface of the alloy was then ground and polished to a surface roughness of less than 0.5 μm. The alloy was then ultrasonically cleaned with acetone and anhydrous ethanol for 20 minutes and placed in a vacuum drying oven for later use.

[0047] The alloy surface was ground and polished in sequence until the surface roughness of the alloy was less than 0.5 μm, and then ultrasonically cleaned with acetone and anhydrous ethanol for 20 min respectively, and then placed in a vacuum drying oven for use. It was then sputter-cleaned with argon gas at a gas flow rate of 50 sccm and a working pressure of 4.0×10 -1 Pa, the treatment time is 20min, and then the surface of the alloy sample is simultaneously implanted with Zr, Ti, Zn, and Cr ions. The implantation ratio of Zr / Ti ions is 2, and the implantation ratio of Zn / Cr ions is 1.5. The implantation dose of Zr ions is 3×10 17 ions·cm 2 The Zn ion implantation dose is 1×10 17 ions·cm 2 The purity of the ion source is greater than 99.9%. The environmental vacuum is 3×10 -4 Pa, the accelerating voltage of ion implantation is 60 kV, the beam current is 0.1 mA, and the implantation time is 2 h.

[0048] The performance test of the obtained alloy showed that the hardness of the alloy was 1672HV by Vickers hardness test, and the wear rate of the matrix was 14.25*10 -14 mm 3 / N·mm, friction coefficient is 0.147, ultimate fatigue strength is 489MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The V of the alloy is -0.531, the maximum depth of intergranular corrosion is 34.1 μm, and the exfoliation corrosion grade is above PA grade. The stress corrosion sensitivity of the alloy in a corrosion environment at 35 ° C is I SSRT =4.52%.

[0049] Example 4

[0050] A method for improving the corrosion resistance of an Al-Cu-Li alloy by composite ion implantation comprises the following steps:

[0051] The alloy was subjected to extrusion deformation treatment at an extrusion temperature of 420 °C and an extrusion ratio of 12:1. The surface of the alloy was then ground and polished in sequence. After polishing to a surface roughness of less than 0.5 μm, the alloy was ultrasonically cleaned with acetone and anhydrous ethanol for 15 min respectively and placed in a vacuum drying oven for later use. It was then sputter-cleaned with argon gas at a gas flow rate of 35 sccm and a working pressure of 8.0×10 -1 Pa, the treatment time is 20min, and then the surface of the alloy sample is simultaneously implanted with Zr, Ti, Zn, and Cr ions. The implantation ratio of Zr / Ti ions is 1, and the implantation ratio of Zn / Cr ions is 1.5. The implantation dose of Zr ions is 2×10 17 ions·cm 2 The Zn ion implantation dose is 2.5×10 17 ions·cm 2 The purity of the ion source is greater than 99.9%. The environmental vacuum is 3×10 -4 Pa, the accelerating voltage of ion implantation is 40 kV, the beam current is 0.1 mA, and the implantation time is 0.5 h.

[0052] The performance test of the obtained alloy showed that the hardness of the alloy was 1611HV by Vickers hardness test, and the wear rate of the substrate was 14.98*10 -14 mm 3 / N·mm, friction coefficient is 0.143, ultimate fatigue strength is 493MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The V of the alloy is -0.526V, the maximum depth of intergranular corrosion is 36.4μm, and the exfoliation corrosion grade is above PA grade. The stress corrosion sensitivity of the alloy in a corrosion environment at 35℃ is I SSRT =4.64%.

[0053] Example 5

[0054] A method for improving the corrosion resistance of an Al-Cu-Li alloy by composite ion implantation comprises the following steps:

[0055] The alloy was subjected to extrusion deformation treatment at an extrusion temperature of 480 °C and an extrusion ratio of 25:1. The surface of the alloy was then ground and polished in sequence. After polishing to a surface roughness of less than 0.5 μm, the alloy was ultrasonically cleaned with acetone and anhydrous ethanol for 20 min respectively and placed in a vacuum drying oven for later use. It was then sputter-cleaned with argon gas at a gas flow rate of 45 sccm and a working pressure of 7.0×10 -1 Pa, the treatment time is 10min, and then the surface of the alloy sample is simultaneously implanted with Zr, Ti, Zn, and Cr ions. The implantation ratio of Zr / Ti ions is 3, and the implantation ratio of Zn / Cr ions is 1.5. The implantation dose of Zr ions is 1.5×10 17 The Zn ion implantation dose is 3×10 17 ions·cm 2 The purity of the ion source is greater than 99.9%. The environmental vacuum is 2×10 -4 Pa, the accelerating voltage of ion implantation is 40 kV, the beam current is 0.1 mA, and the implantation time is 2.5 h.

[0056] The performance test of the obtained alloy showed that the hardness of the alloy was 1595HV by Vickers hardness test, and the wear rate of the matrix was 15.27*10 -14 mm 3 / N·mm, friction coefficient is 0.145, ultimate fatigue strength is 485MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The V is -0.531, the maximum depth of intergranular corrosion is 36.9 μm, and the exfoliation corrosion grade is above PA grade. The stress corrosion sensitivity of the alloy in a corrosion environment at 35 ° C is I SSRT =4.72%.

[0057] Comparative Example 1

[0058] The extrusion deformation and pretreatment of the alloy in this comparative example are the same as those in Example 2. The only difference is that only Zr and Ti ions are compositely implanted on the surface, where the Zr / Ti ion implantation ratio is 2 and the Zr ion implantation dose is 2.5×10 17 ions·cm 2 .

[0059] The performance test of the obtained alloy showed that the hardness of the alloy was 698HV by Vickers hardness test, and the wear rate of the substrate was 20.97*10 -14 mm 3 / N·mm, friction coefficient is 0.210, ultimate fatigue strength is 378MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The V of the alloy is -0.668, the maximum depth of intergranular corrosion is 80.2 μm, and the exfoliation corrosion grade is above PB grade. The stress corrosion sensitivity of the alloy in a corrosion environment at 35 ° C is I SSRT =8.01%.

[0060] Comparative Example 2

[0061] The extrusion deformation and pretreatment of the alloy in this comparative example are the same as those in Example 2. The only difference is that the alloy is simultaneously implanted with Zn and Cr ions, wherein the implantation ratio of Zn / Cr ions is 2 and the implantation dose of Zn ions is 2×10 17 ions·cm 2 .

[0062] The performance test of the obtained alloy showed that the hardness of the alloy was 687HV by Vickers hardness test, and the wear rate of the substrate was 23.65*10 -14 mm 3 / N·mm, friction coefficient is 0.198, ultimate fatigue strength is 386MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The V of the alloy is -0.661V, the maximum depth of intergranular corrosion is 79.7μm, and the exfoliation corrosion level is above PB level. The stress corrosion sensitivity of the alloy in a corrosion environment at 35℃ is I SSRT =7.99%.

[0063] Comparative Example 3

[0064] The extrusion deformation and pretreatment of the alloy in this comparative example are the same as those in Example 2, except that only Zr ions are implanted into the alloy, wherein the Zr ion implantation dose is 2.5×10 17 ions·cm 2 .

[0065] The performance test of the obtained alloy showed that the hardness of the alloy was 576HV by Vickers hardness test, and the wear rate of the matrix was 30.41*10 -14 mm 3 / N·mm, friction coefficient is 0.302, ultimate fatigue strength is 328MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The V of the alloy is -0.699V, the maximum depth of intergranular corrosion is 96.9μm, and the exfoliation corrosion level is above PB level. The stress corrosion sensitivity of the alloy in a corrosion environment at 35℃ is I SSRT =9.19%.

[0066] Comparative Example 4

[0067] The extrusion deformation and pretreatment of the alloy in this comparative example are the same as those in Example 2, except that the alloy is not subjected to ion implantation.

[0068] The performance test of the obtained alloy showed that the hardness of the alloy was 230HV by Vickers hardness test, and the wear rate of the substrate was 49.87*10 -14 mm 3 / N·mm, friction coefficient is 0.532, ultimate fatigue strength is 220MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The maximum depth of intergranular corrosion is 109.2μm, the exfoliation corrosion grade is above PB, and the stress corrosion sensitivity of the alloy in a corrosion environment of 35℃ is I SSRT =10.27%.

[0069] Comparative Example 5

[0070] The pretreatment method and ion implantation conditions of the alloy in this comparative example are the same as those in Example 2, the only difference being that the alloy is not subjected to extrusion deformation treatment.

[0071] The performance test of the obtained alloy showed that the hardness of the alloy was 423HV by Vickers hardness test, and the wear rate of the matrix was 33.61*10 -14 mm 3 / N·mm, friction coefficient is 0.311, ultimate fatigue strength is 298MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The maximum depth of intergranular corrosion is 98.5 μm, the exfoliation corrosion grade is above PB, and the stress corrosion sensitivity of the alloy in a 35°C corrosion environment is I SSRT =9.56%.

[0072] Comparative Example 6

[0073] The extrusion deformation and pretreatment of the alloy in this comparative example are the same as those in Example 2, except that the alloy is simultaneously implanted with Zr and Cr ions, with the Zr ion implantation dose of 2.5×10 17 ions·cm 2 The Cr ion implantation dose is 1×10 17 ions·cm 2 .

[0074] The performance test of the obtained alloy showed that the hardness of the alloy was 581HV by Vickers hardness test, and the wear rate of the matrix was 27.84*10 -14 mm 3 / N·mm, friction coefficient is 0.293, ultimate fatigue strength is 339MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The maximum depth of intergranular corrosion is 82.3 μm, the exfoliation corrosion grade is above PB, and the stress corrosion sensitivity of the alloy in a 35°C corrosion environment is I SSRT =8.14%.

[0075] Comparative Example 7

[0076] The extrusion deformation and pretreatment of the alloy in this comparative example are the same as those in Example 2, except that the alloy is simultaneously implanted with Zr, Cr, and Ti ions, with the Zr ion implantation dose of 2.5×10 17 ions·cm 2 The Cr ion implantation dose is 1×10 17 ions·cm 2 , the Ti ion implantation dose is 1.25×10 17 ions·cm 2 .

[0077] The performance test of the obtained alloy showed that the hardness of the alloy was 702HV by Vickers hardness test, and the wear rate of the substrate was 17.54*10 -14 mm 3 / N·mm, friction coefficient is 0.187, ultimate fatigue strength is 391MPa, and the alloy corrosion potential V is measured by electrochemical workstation SCE The maximum depth of intergranular corrosion is 83.6 μm, the exfoliation corrosion grade is above PB, and the stress corrosion sensitivity of the alloy in a 35°C corrosion environment is I SSRT =8.09%.

[0078] The alloy materials prepared in Examples 1-5 and Comparative Examples 1-7 were subjected to Vickers hardness test (according to GB / T4340.1-2009), intergranular corrosion test (according to GB / T 7998-2005) test and exfoliation corrosion test (according to GB / T22639-2008). The friction and wear performance, fatigue performance and corrosion performance parameters of the Examples and Comparative Examples are shown in Table 1. It can be seen from Table 1 that after the alloy is subjected to ion implantation, the damage resistance of the alloy is greatly improved, the hardness reaches 1700HV, which is 7.8 times higher than that of the alloy without ion implantation; the friction coefficient reaches below 0.15, the fatigue limit strength reaches 600Mpa; the corrosion potential V SCE Below -0.65V, the intergranular corrosion resistance level is Level 1, the exfoliation corrosion level is above Level EA, and the stress corrosion sensitivity ISSRT is less than 5.0%.

[0079] Table 1

[0080]

[0081] It can be seen from Comparative Example 1 that only Zr and Ti ions are injected, and the modified layer is relatively thin, forming only Al3 (Zr, Ti) phase in the alloy. Although the wear resistance and strength of the alloy are improved, the T1 phase potential in the alloy is relatively negative. When the modified layer is destroyed, the substrate is exposed and local corrosion is prone to occur, so its test performance is relatively low.

[0082] It can be seen from Comparative Example 2 that only Zn and Cr ions are injected, and the modified layer is relatively thin. (Al2(Cu,Zn)Li) phase and Al-Cr-Mn phase are formed in the alloy. Although the corrosion resistance of the alloy is improved, the strength and wear resistance of the alloy are not significantly improved, so its test performance is relatively low.

[0083] It can be seen from Comparative Example 3 that only Zr ions are injected, the modified layer is thin, and only Al3Zr phase is formed in the alloy. The corrosion resistance, wear resistance and fatigue resistance of the alloy are not significantly improved, so its test performance is low.

[0084] It can be seen from Comparative Example 4 that no ion implantation was performed and the alloy was not subjected to surface strengthening treatment, so its test performance was relatively low.

[0085] Comparative Example 5 shows that Zr, Ti, Zn, and Cr ions were implanted without extrusion deformation. Extrusion deformation promotes the formation of numerous defects, such as subgrain boundaries and dislocations, which further promotes the transition from conventional ion diffusion in the alloy to short-range diffusion, thereby achieving a certain penetration depth. However, the alloy without extrusion deformation exhibits a thinner penetration layer, resulting in lower test performance.

[0086] It can be seen from Comparative Example 6 that only Zr and Cr ions are injected, and the modified layer is relatively thin. Al3Zr phase and Al-Cr-Mn phase can be formed in the alloy. Although the wear resistance and stress corrosion resistance of the alloy are improved, the T1 phase potential in the alloy is relatively negative. When the modified layer is destroyed, the substrate is exposed and local corrosion is prone to occur. Therefore, its test performance is relatively low.

[0087] It can be seen from Comparative Example 7 that only three ions, Zr, Cr, and Ti, are injected, and Al3 (Zr, Ti) phase and Al-Cr-Mn phase can be formed in the alloy. Although the wear resistance, fatigue resistance, and stress corrosion resistance of the alloy are improved, the T1 phase potential in the alloy is relatively negative. When the modified layer is destroyed, the substrate is exposed and local corrosion is prone to occur. Therefore, its test performance is relatively low.

[0088] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for improving the corrosion resistance of Al-Cu-Li alloy by composite ion implantation, characterized in that: The method is to compositely implant Zr, Ti, Zn and Cr ions into an Al-Cu-Li alloy, wherein the Zr / Ti ion implantation dosage ratio is 1 to 3:1, and the Zn / Cr ion implantation dosage ratio is 1.5 to 2.5:1; The Zr ion implantation dose is 1.5×10 17 ~3×10 17 ions·cm 2 The implantation dose of Ti ions is 0.5×10 17 ~3×10 17 ions·cm 2 The Zn ion implantation dose is 1×10 17 ~3×10 17 ions·cm 2 The Cr ion implantation dose is 0.4×10 17 ~2×10 17 ions·cm 2 ; The method comprises the following steps: S1: subjecting Al-Cu-Li alloy to thermoplastic deformation treatment; S2: pretreating the surface of the deformed Al-Cu-Li alloy obtained in S1; S3: composite implantation of Zr, Ti, Zn, and Cr ions into the deformed Al-Cu-Li alloy after treatment in S2 to obtain a composite Al-Cu-Li alloy material; In step S1, the thermoplastic deformation treatment includes extrusion deformation treatment of the Al-Cu-Li alloy, the extrusion temperature is 400°C to 500°C, and the extrusion ratio is 4 to 25:

1.

2. The method according to claim 1, characterized in that In step S2, the pretreatment includes: grinding the surface of the deformed Al-Cu-Li alloy, polishing the alloy with a polishing liquid, ultrasonically cleaning the alloy, and finally sputtering the alloy with argon.

3. The method according to claim 2, characterized in that The polishing treatment includes: polishing the alloy surface in sequence using 300 mesh, 1200 mesh, 3000 mesh and 7000 mesh sandpaper; and polishing with polishing liquid until the surface roughness of the alloy is less than 0.5 μm.

4. The method according to claim 2, characterized in that The argon gas flow rate of the argon sputtering cleaning is 30-50 sccm, and the working pressure is 2.0×10 -1 ~8.0×10 -1 Pa, processing time is 10 to 20 minutes.

5. The method according to claim 1, characterized in that In step S3, the composite injection environment is vacuum, and the vacuum degree is 1.5×10 -4 ~4×10 -4 Pa.

6. The method according to claim 1, characterized in that In step S3, the acceleration voltage of the composite injection is 40-70 kV, the beam current is 0.1 mA, and the injection time is 0.5-2.5 h.

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