An analysis method and system for simulating pitting corrosion damage mechanism of aluminum alloy under seawater immersion environment

Abstract

The application provides an analysis method and system for simulating the pitting corrosion damage mechanism of aluminum alloy under seawater immersion environment, and the method comprises the following steps: determining the phase composition of target intermetallic compound particles for inducing pitting corrosion in an aluminum alloy sample; preparing pure phase samples of each single phase, and constructing a coupling system model of each single phase and an aluminum matrix; performing a simulated seawater immersion corrosion test, and performing multi-scale electrochemical characterization to obtain the electrochemical activity difference of each phase; obtaining the surface stability, reaction activity, bulk phase structure stability and interface charge transfer characteristics of each phase; and performing comparative analysis to determine the micro galvanic mechanism of the target intermetallic compound particles for inducing pitting corrosion. The technical scheme provided by the application can systematically reveal the complete mechanism of intermetallic compound particles inducing pitting corrosion of aluminum alloy through internal complex galvanic pairs, and provide a theoretical basis for component design and process optimization of high corrosion-resistant aluminum alloy.

Description

Technical Field

[0001] This application relates to the field of metal material corrosion science and failure analysis technology, and in particular to an analytical method and system for simulating the pitting corrosion damage mechanism of aluminum alloys under seawater immersion environment. Background Technology

[0002] The complex microstructure of aluminum alloys, particularly intermetallic compound particles and second phases, is a key factor in inducing and dominating localized corrosion. These precipitated phases have inherent electrochemical differences from the aluminum matrix, forming microscopic electrical couples in the corrosive medium, acting as "galvanic cells" that induce pitting corrosion. Further complicating matters, corrosion behavior is synergistically controlled by thermomechanical processing conditions and microstructure. For example, studies have found that the high steady-state pitting susceptibility of alloys is attributed to non-uniform plastic deformation during pre-cooling stretching and non-uniform precipitation of strengthening phases during artificial aging. Besides static galvanic corrosion, aluminum alloys often face the synergistic effects of stress and the corrosive environment in actual service. Research shows that stress corrosion cracking is significantly accelerated in aluminum alloys with pre-corrosion pits, and cracks between double pits can coalesce, leading to faster failure.

[0003] Faced with such complex corrosion failure mechanisms, traditional corrosion analysis methods are insufficient. Traditional methods often focus on macroscopic electrochemical tests (such as polarization curves and electrochemical impedance spectroscopy) or single-scale morphological observations (such as scanning electron microscopy). While these methods can reflect the overall corrosion rate or final corrosion morphology of the material, they struggle to dynamically and in-situ reveal the microscopic processes in the early stages of corrosion initiation, and they cannot accurately distinguish the specific electrochemical roles and mechanisms of each phase within multiphase particles. For example, macroscopic electrochemical impedance spectroscopy cannot tell us on which phase of complex particles the current is concentrated, and SEM morphological observation can only show the post-corrosion results. Therefore, there is an urgent need to propose an innovative, multi-scale coupled analytical scheme. Summary of the Invention

[0004] This application provides an analytical method and system for simulating the pitting corrosion damage mechanism of aluminum alloys under seawater immersion conditions, so as to at least solve the technical problem that traditional analytical methods are unable to systematically reveal the specific electrochemical roles and microscopic mechanisms of each component phase in multiphase intermetallic compound particles in the pitting corrosion initiation process of aluminum alloys.

[0005] The first aspect of this application proposes an analytical method for simulating the pitting corrosion damage mechanism of aluminum alloys under seawater immersion conditions, the method comprising:

[0006] Determine the phase composition of the target intermetallic compound particles that induce pitting corrosion in aluminum alloy samples; Pure phase samples of each single phase were prepared according to the phase composition, and a coupling system model of each single phase and the aluminum matrix was constructed. A simulated full-immersion corrosion test in seawater was conducted on the aluminum alloy sample and the coupled system model, and multi-scale electrochemical characterization was performed to obtain the differences in electrochemical activity of each phase. First-principles calculations based on density functional theory were performed on the phase composition to obtain the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase. By comparing and analyzing the differences in electrochemical activity of each phase with the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase, the micro-couple mechanism of pitting corrosion induced by the target intermetallic compound particles was determined.

[0007] Preferably, determining the phase composition of the target intermetallic compound particles that induce pitting corrosion in the aluminum alloy sample includes: The analytical locations of the target intermetallic compound particles on the surface of the aluminum alloy sample were determined using scanning electron microscopy. The phase composition of the target intermetallic compound particles was obtained at the analysis location using electron backscatter diffraction.

[0008] Preferably, the step of preparing pure-phase samples of each single phase according to the phase composition and constructing a coupling system model of each single phase with the aluminum matrix includes: Bulk pure phase samples of each single phase were prepared by spark plasma sintering technology. Aluminum powder was used to simulate the aluminum alloy matrix. Bulk pure phase samples of each single phase were sintered with aluminum powder by spark plasma sintering technology to construct a coupling system model of each single phase and the aluminum matrix.

[0009] Furthermore, X-ray diffraction was used to verify the phase structure of the prepared single-phase bulk pure-phase sample.

[0010] Preferably, the seawater is a 3.5% NaCl solution by mass.

[0011] Furthermore, the multi-scale electrochemical characterization to obtain the differences in electrochemical activity of each phase includes: The potential distribution of each phase region on the surface of the coupled system model relative to the aluminum substrate was measured using scanning Kelvin probe technology. The local current density distribution on the surface of the coupled system model was monitored using scanning vibration electrode technology; Electrochemical impedance spectroscopy was performed on a single-phase sample, and the charge transfer resistance parameters were obtained by equivalent circuit fitting. The differences in electrochemical activity of each phase are obtained based on the potential distribution, local current density distribution, and charge transfer resistance parameters.

[0012] Furthermore, the first-principles calculations based on density functional theory, performed on the phase composition to obtain the surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics of each phase, include: The exposed surfaces of each phase were selected based on the results of electron backscatter diffraction and X-ray diffraction. The surface energy of the selected exposed surface was calculated using VASP software and the PBE-GGA exchange-correlation functional. Calculate the adsorption energies of oxygen and chloride ions on the exposed surfaces of each phase; Calculate the electron localization function of each phase in bulk; Calculate the charge density difference at the heterojunction interface between each phase and the aluminum matrix; Based on the surface energy, adsorption energy, electronic localization function, and charge density difference, the surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics of each phase are obtained.

[0013] Preferably, the step of comparing and analyzing the differences in electrochemical activity of each phase with the surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics of each phase to determine the micro-couple mechanism of pitting corrosion induced by the target intermetallic compound particles includes: Based on the potential distribution and local current density distribution in the electrochemical activity differences, the cathode or anode properties of each constituent phase of the target intermetallic compound particles are determined. The determined cathode or anode properties are verified based on the surface stability, reactivity, bulk structure stability, and interfacial charge transfer characteristics. When the determined cathode or anode properties are consistent with the verification results, the micro-electrical couples formed between each anode phase and the aluminum substrate, and between each cathode phase and the aluminum substrate, are determined according to the direction of electron loss or enrichment in the interface charge transfer characteristics.

[0014] A second aspect of this application provides an analytical system for simulating the pitting corrosion damage mechanism of aluminum alloys under seawater immersion conditions. The system includes: The determination module is used to determine the phase composition of the target intermetallic compound particles that induce pitting corrosion in aluminum alloy samples. A construction module is used to prepare pure phase samples of each single phase according to the phase composition, and to construct a coupling system model of each single phase and the aluminum matrix. The characterization module is used to simulate full seawater immersion corrosion tests on aluminum alloy samples and the coupled system model, and to perform multi-scale electrochemical characterization to obtain the differences in electrochemical activity of each phase. The calculation module is used to perform first-principles calculations based on density functional theory based on the phase composition to obtain the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase. The comparative analysis module is used to compare and analyze the differences in electrochemical activity of each phase with the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase, so as to determine the micro-couple mechanism of pitting corrosion induced by the target intermetallic compound particles.

[0015] A third aspect of this application provides a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the method proposed in the first aspect.

[0016] The technical solutions provided by the embodiments of this application have at least the following beneficial effects: This application proposes an analytical method and system for simulating the pitting corrosion damage mechanism of aluminum alloys under seawater immersion conditions. The method includes: determining the phase composition of the target intermetallic compound particles that induce pitting corrosion in the aluminum alloy sample; preparing pure phase samples of each single phase according to the phase composition, and constructing a coupled system model of each single phase and the aluminum matrix; conducting simulated full immersion corrosion tests in seawater on the aluminum alloy sample and the coupled system model, and performing multi-scale electrochemical characterization to obtain the differences in electrochemical activity of each phase; performing first-principles calculations based on density functional theory based on the phase composition to obtain the surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics of each phase; comparing and analyzing the differences in electrochemical activity of each phase with the surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics of each phase to determine the microscopic electrocouple mechanism of pitting corrosion induced by the target intermetallic compound particles. The technical solution proposed in this application organically combines macroscopic experiments, microscopic characterization, and atomic-scale calculations, which can systematically reveal the complete mechanism by which intermetallic compound particles induce pitting corrosion in aluminum alloys through complex internal electrical couples, providing a theoretical basis for the composition design and process optimization of high corrosion-resistant aluminum alloys.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart illustrating an analytical method for simulating pitting damage mechanisms in aluminum alloys under simulated seawater immersion conditions, according to an embodiment of this application. Figure 2 This is an analysis diagram of pitting damage morphology of aluminum alloy under simulated seawater immersion environment according to an embodiment of this application; Figure 3This is a schematic diagram of the phase distribution map of intermetallic compound particle regions in an aluminum alloy according to an embodiment of this application, based on EBSD test results. Figure 4a The XRD pattern of Al4Cu9 prepared by plasma sintering according to an embodiment of this application; Figure 4b Cu3Fe prepared by plasma sintering according to one embodiment of this application 17 XRD patterns; Figure 4c Fe prepared by plasma sintering according to one embodiment of this application 19 XRD pattern of Mn; Figure 5a A secondary scanning electron microscope image of intermetallic compound particles in an aluminum alloy before immersion, according to an embodiment of this application; Figure 5b A secondary scanning electron microscope image of intermetallic compound particles in an aluminum alloy after immersion in a 3.5 wt.% NaCl solution, according to an embodiment of this application; Figure 6a This is a schematic diagram of a coupling system of three phases with an aluminum matrix prepared by plasma sintering according to an embodiment of this application; Figure 6b This is a Kelvin potential distribution diagram of a coupling system of three phases and an alloy matrix prepared by spark plasma sintering according to an embodiment of this application; Figure 6c The scanning vibration electrode current density diagram shows the three phases prepared by spark plasma sintering technology according to an embodiment of this application after immersion in 3.5 wt.% NaCl solution. Figure 7a The image shows the Nyquist plots of three phase electrochemical impedance spectroscopy (EIS) spectra of three phases prepared by spark plasma sintering according to an embodiment of this application. Figure 7b The image shows the electrochemical impedance spectroscopy-Bode diagrams of three phases prepared by spark plasma sintering according to an embodiment of this application. Figure 7c This is a schematic diagram of the equivalent circuit fitting result provided according to an embodiment of this application; Figure 8a This is a schematic diagram of the adsorption sites for oxygen adsorption at the top site, bridge site, and fcc site on the Al4Cu9(330) surface according to an embodiment of this application. Figure 8b Oxygen in Cu3Fe according to one embodiment of this application17 (110) Schematic diagram of adsorption sites for surface top site adsorption, bridge site adsorption and fcc adsorption; Figure 8c Oxygen in Fe according to one embodiment of this application 19 Schematic diagram of adsorption sites for top site adsorption, bridge site adsorption and fcc adsorption on the Mn(310) surface; Figure 9a A two-dimensional electron localization function graph of Al4Cu9 according to an embodiment of this application; Figure 9b Cu3Fe according to one embodiment of this application 17 Two-dimensional electron local function graph; Figure 9c Fe provided according to one embodiment of this application 19 Two-dimensional electron local function plot of Mn; Figure 10a This is a schematic diagram of charge transfer at the Al4Cu9-Al matrix interface based on first principles, according to an embodiment of this application. Figure 10b Cu3Fe based on first-principles calculations according to one embodiment of this application 17 Schematic diagram of charge transfer at the interface with the Al matrix; Figure 10c For the Fe based on first principles provided according to an embodiment of this application 19 Schematic diagram of charge transfer at the interface between Mn and Al matrix; Figure 11 A detailed flowchart of an analytical method for simulating pitting damage mechanism of aluminum alloy under seawater immersion environment according to an embodiment of this application; Figure 12 This is a structural diagram of an analysis system for simulating the pitting damage mechanism of aluminum alloys under seawater immersion environment, according to an embodiment of this application. Detailed Implementation

[0019] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0020] This application proposes an analytical method and system for simulating the pitting corrosion damage mechanism of aluminum alloys under simulated seawater immersion conditions. The method includes: determining the phase composition of the target intermetallic compound particles that induce pitting corrosion in the aluminum alloy sample; preparing pure phase samples of each single phase according to the phase composition, and constructing a coupled system model of each single phase and the aluminum matrix; conducting simulated full seawater immersion corrosion tests on the aluminum alloy sample and the coupled system model, and performing multi-scale electrochemical characterization to obtain the differences in electrochemical activity of each phase; performing first-principles calculations based on density functional theory based on the phase composition to obtain the surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics of each phase; comparing and analyzing the differences in electrochemical activity of each phase with the surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics of each phase to determine the microscopic electrocouple mechanism of pitting corrosion induced by the target intermetallic compound particles. The technical solution proposed in this application organically combines macroscopic experiments, microscopic characterization, and atomic-scale calculations, which can systematically reveal the complete mechanism by which intermetallic compound particles induce pitting corrosion in aluminum alloys through complex internal electrical couples, providing a theoretical basis for the composition design and process optimization of high corrosion-resistant aluminum alloys.

[0021] The following describes, with reference to the accompanying drawings, an analytical method and system for simulating pitting damage mechanism of aluminum alloy under seawater immersion environment, according to an embodiment of this application.

[0022] Example 1 Figure 1 This is a flowchart illustrating an analytical method for simulating pitting corrosion damage mechanisms in aluminum alloys under simulated seawater immersion conditions, according to an embodiment of this application. Figure 1 As shown, the method includes: Step 1: Determine the phase composition of the target intermetallic compound particles that induce pitting corrosion in the aluminum alloy sample; In this embodiment of the disclosure, step 1 specifically includes: The analytical locations of the target intermetallic compound particles on the surface of the aluminum alloy sample were determined using scanning electron microscopy. The phase composition of the target intermetallic compound particles was obtained at the analysis location using electron backscatter diffraction.

[0023] It should be noted that the aluminum alloy sample to be analyzed was prepared and polished. Scanning electron microscopy combined with energy dispersive spectroscopy was used to locate and preliminarily determine the morphology, size distribution, and main elemental composition of the target intermetallic compound particles that induced pitting corrosion. Further, electron backscatter diffraction was used to perform high-resolution phase distribution analysis on the target intermetallic compound particle region to precisely determine the specific phases it consists of.

[0024] Step 2: Prepare pure phase samples of each single phase according to the phase composition, and construct a coupling system model of each single phase and the aluminum matrix; In this embodiment of the disclosure, step 2 specifically includes: Bulk pure phase samples of each single phase were prepared by spark plasma sintering technology. Aluminum powder was used to simulate the aluminum alloy matrix. Bulk pure phase samples of each single phase were sintered with aluminum powder by spark plasma sintering technology to construct a coupling system model of each single phase and the aluminum matrix.

[0025] Furthermore, step 2 also includes: X-ray diffraction was used to verify the phase structure of the prepared single-phase bulk pure-phase sample.

[0026] It should be noted that, based on the determined phases of the intermetallic compound particles, powder metallurgy technology, preferably spark plasma sintering, was used to prepare bulk pure-phase samples of each single phase. Simultaneously, aluminum powder was used to simulate the aluminum alloy matrix. Each single-phase sample and aluminum powder were sintered using the same powder metallurgy technology to construct a binary coupled system model of "phase / aluminum matrix," which simulates the actual contact state between the intermetallic compound particles and the surrounding aluminum matrix in the actual alloy. X-ray diffraction was used to verify the phase structure of the prepared single-phase samples, ensuring that their crystal structure is consistent with the corresponding phases in the actual particles.

[0027] Step 3: Conduct simulated seawater full immersion corrosion tests on the aluminum alloy samples and the coupled system model, and perform multi-scale electrochemical characterization to obtain the differences in electrochemical activity of each phase; In this embodiment of the disclosure, the seawater is a 3.5% NaCl solution by mass.

[0028] In this embodiment of the disclosure, the step of performing multi-scale electrochemical characterization to obtain differences in the electrochemical activity of each phase includes: The potential distribution of each phase region on the surface of the coupled system model relative to the aluminum substrate was measured using scanning Kelvin probe technology. The local current density distribution on the surface of the coupled system model was monitored using scanning vibration electrode technology; Electrochemical impedance spectroscopy was performed on a single-phase sample, and the charge transfer resistance parameters were obtained by equivalent circuit fitting. The differences in electrochemical activity of each phase are obtained based on the potential distribution, local current density distribution, and charge transfer resistance parameters.

[0029] It should be noted that both the actual aluminum alloy samples and the constructed "phase / aluminum matrix" coupled system samples were immersed in simulated seawater for a full immersion corrosion test. Scanning electron microscopy was used to observe and compare the evolution of corrosion morphology at the target particles in the actual alloy and on the surface of the coupled system samples before and after immersion.

[0030] Step 4: Perform first-principles calculations based on density functional theory based on the phase composition to obtain the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase. In this embodiment of the disclosure, step 4 specifically includes: The exposed surfaces of each phase were selected based on the results of electron backscatter diffraction and X-ray diffraction. The surface energy of the selected exposed surface was calculated using VASP software and the PBE-GGA exchange-correlation functional. Calculate the adsorption energies of oxygen and chloride ions on the exposed surfaces of each phase; Calculate the electron localization function of each phase in bulk; Calculate the charge density difference at the heterojunction interface between each phase and the aluminum matrix; Based on the surface energy, adsorption energy, electronic localization function, and charge density difference, the surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics of each phase are obtained.

[0031] It should be noted that a series of electrochemical tests were performed on the coupled system samples and the single-phase samples: ① Using scanning Kelvin probe technology, the voltaic potential distribution of each phase region on the surface of the coupled system relative to the aluminum substrate is measured at the microscale to qualitatively determine the cathodic / anodic tendency of each phase.

[0032] ② By employing scanning vibration electrode technology, the local current density distribution on the surface of the coupling system is monitored in real time during the immersion process, which visually displays the location and intensity of the cathode and anodic reactions.

[0033] ③ Electrochemical impedance spectroscopy was performed on single-phase samples, and parameters such as charge transfer resistance were obtained by equivalent circuit fitting. The differences in interfacial reaction resistance and corrosion resistance of each phase in the corrosive medium were quantitatively compared.

[0034] ④ Calculate the charge density difference at the “phase / aluminum” heterojunction interface, analyze the direction of electron transfer and enrichment at the interface, and reveal the formation mechanism of electric couples at the electronic scale.

[0035] Step 5: Compare and analyze the differences in electrochemical activity of each phase with the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase to determine the micro-couple mechanism of pitting corrosion induced by the target intermetallic compound particles.

[0036] In this embodiment of the disclosure, step 5 specifically includes: Based on the potential distribution and local current density distribution in the electrochemical activity differences, the cathode or anode properties of each constituent phase of the target intermetallic compound particles are determined. The determined cathode or anode properties are verified based on the surface stability, reactivity, bulk structure stability, and interfacial charge transfer characteristics. When the determined cathode or anode properties are consistent with the verification results, the micro-electrical couples formed between each anode phase and the aluminum substrate, and between each cathode phase and the aluminum substrate, are determined according to the direction of electron loss or enrichment in the interface charge transfer characteristics.

[0037] It should be noted that the comprehensive analysis and conclusions of the pitting damage mechanism lead to the following: ① Determine the specific multiphase composition of the target intermetallic compound particles.

[0038] ② By analyzing the corrosion morphology and Kelvin potential distribution, determine the cathodic / anodic role of each component phase in the actual corrosion process.

[0039] ③ By scanning vibrational electrode test and electrochemical impedance spectroscopy data, the differences in electrochemical activity of each phase were verified and quantified.

[0040] ④ By using first-principles calculations of surface energy, adsorption energy, electronic localization function, and charge density difference results, the intrinsic physical nature of the different electrochemical behaviors (cathodic or anodic) of each phase is elucidated at the atomic / electronic scale, including surface stability, reaction driving force, bulk structural stability, and interfacial charge transfer direction.

[0041] ⑤ Finally, the system reveals the micro-electrical coupling mechanism of pitting corrosion in aluminum alloys induced by the multiphase intermetallic compound particles in a simulated seawater environment, and clarifies the specific role and contribution of each constituent phase in the pitting corrosion initiation stage.

[0042] The following is a detailed explanation of the analytical method for simulating the pitting damage mechanism of aluminum alloys under seawater immersion conditions proposed in this embodiment: Step S1: Microstructure characterization and phase composition determination.

[0043] Aluminum alloy metallographic samples were prepared and polished. SEM-EDS was used to identify intermetallic compound particles rich in Al, Cu, Mn, and Fe. Figure 2 As shown. Further high-resolution EBSD analysis of this region clearly showed that the particle consisted of Al4Cu9 and Cu3Fe. 17 and Fe 19 Mn three-phase composition, such as Figure 3 As shown.

[0044] Step S2: Construction and verification of the simulated coupled system.

[0045] Using spark plasma sintering technology, Al4Cu9 and Cu3Fe were prepared from pure Al, Cu, Mn, and Fe powders respectively, and held at 600℃ and 80 MPa pressure for 2 minutes. 177 and Fe 19 Large-scale pure-phase Mn samples were prepared. Simultaneously, smaller pure-phase samples were sintered with aluminum powder using the same process to construct (Al4Cu9, Cu3Fe) samples. 17 Fe 19 The Mn / Al coupling system was confirmed by XRD analysis to have a pure-phase crystal structure consistent with its PDF standard card. Figure 4a , 4b As shown in 4c.

[0046] Step S3: Corrosion behavior and electrochemical testing.

[0047] The alloy sample and the coupled system sample were immersed in a 3.5 wt.% NaCl solution. SEM observation revealed two morphologies at the actual alloy particles: grooves formed by the dissolution of the aluminum matrix around the Al4Cu9 phase, and... 17 and Fe 19 The Mn phase itself exhibits pitting corrosion of 1-3 μm, such as Figure 5a , 5b As shown.

[0048] Scanning Kelvin probe microanalysis showed that the Al4Cu9 phase potential was approximately 300 mV higher than that of the aluminum substrate at the surface of the coupled system, while that of Cu3Fe was lower. 177 and Fe 19 The Mn phase potential is about 300 mV lower than that of the aluminum matrix. Thermodynamically, this explains the difference between Al4Cu9 and Cu3Fe. 17 and Fe 19 The Mn phase is more stable and less prone to corrosion. Scanning vibration electrode testing detected Cu3Fe during the immersion process. 17 and Fe 19 A significant concentration of anodic current appears at the Mn phase location, such as Figure 6a , 6b As shown in Figure 6c, this indicates that Cu3Fe 17 and Fe 19 The Mn phase is more prone to corrosion, generating corrosion current.

[0049] Electrochemical impedance spectroscopy (EIS) measurements and fitting showed that the charge transfer resistance of the Al4Cu9 phase was ~5.9 × 10⁻⁶. 4 Ω cm² is much higher than Cu3Fe 17 Phase (~5.3×10³ Ω cm²) and Fe 19Mn phase (~6.9×10³ Ω cm²), such as Figure 7a , 7b As shown in Figures 7c, the Al4Cu9 phase exhibits better corrosion resistance.

[0050] Step S4: First-principles calculation.

[0051] Construct Al4Cu9(330), Cu3Fe 17 (110), Fe 19 Calculations were performed using the Mn(310) surface model and the corresponding heterojunction model. The calculated surface energy was lowest on Al4Cu9(330) (12.93 eV / Ų), and the adsorption energy of O2 on its surface (-4.19 eV) was higher than that on Cu3Fe. 17 (110) (-5.78 eV) and Fe 19 Mn(310) surface (-5.99 eV), such as Figure 8a , 8b As shown in Figure 8c, this indicates that O2 is more readily produced in Cu3Fe. 177 and Fe 19 Mn adsorption on the two-phase surface leads to a greater tendency for corrosion. Electron localization function analysis shows that the Al-Cu / Al-Al bonds in Al4Cu9 are strongly localized, resulting in a more stable structure. Figure 9a , 9b As shown in Figure 9c, the charge density difference analysis reveals that electrons are enriched on the Al4Cu9 side at the Al4Cu9 / Al interface, while they are enriched on the Cu3Fe side. 17 / Al and Fe 19 Electrons at the Mn / Al interface are lost from the surface of these two phases, such as Figure 10a , 10b As shown in Figure 10c, Cu3Fe 17 and Fe 19 When the Mn two-phase matrix comes into contact with the alloy matrix, it is more likely to lose electrons and be oxidized, thus causing corrosion.

[0052] Step S5: Comprehensive Analysis and Conclusion.

[0053] Based on the above results, it can be concluded that in AlCuMnFe particles of aluminum alloy, the Al4Cu9 phase, due to its high surface stability, low oxygen adsorption activity, strong bulk bonding, and interfacial electron enrichment when coupled with the aluminum matrix, exhibits a cathode phase, leading to anodic dissolution of the surrounding aluminum matrix and the formation of trenches; while Cu3Fe... 17 and Fe 19 The Mn phase, due to its opposite characteristics, exhibits an anodic phase and preferentially dissolves to form pitting corrosion. These particles, through multiple microscopic electrical couples formed by the internal multiphase and the matrix, collectively induce and promote pitting damage in the alloy under simulated seawater conditions.

[0054] Specific implementation methods are as follows Figure 11 As shown, it will not be elaborated further here.

[0055] The analytical method for simulating the pitting corrosion damage mechanism of aluminum alloys under seawater immersion environment proposed in this embodiment has the following advantages: ① Systematicity: This invention organically combines macroscopic immersion experiments, microscopic morphology observation, mesoscopic electrochemical measurements, and atomic-scale calculations, forming a complete analytical chain from actual phenomena to intrinsic mechanisms, overcoming the limitations of single-scale analysis.

[0056] ② Targeted: By constructing a “phase / aluminum matrix” coupled system, it is possible to accurately simulate and separate the interaction between each phase and the matrix in actual complex multiphase particles, clarify the specific contribution of each phase, and solve the problem that traditional methods are difficult to distinguish the interaction of different phases inside multiphase particles.

[0057] ③ In-depth understanding of mechanisms: By introducing first-principles calculations, starting from fundamental physical parameters such as surface energy, adsorption energy, and electronic structure, the root cause of the differences in electrochemical behavior of each phase is quantitatively explained at the atomic / electronic scale, making the mechanism analysis more profound and essential than traditional empirical or semi-empirical explanations.

[0058] ④ Strong applicability: The conclusions drawn from this method can directly guide the composition design of aluminum alloys (such as controlling harmful phases), the optimization of heat treatment processes (such as controlling particle size and distribution), and the formulation of surface protection strategies, providing direct theoretical support for the development of highly corrosion-resistant aluminum alloy materials.

[0059] In summary, the analytical method for simulating the pitting corrosion damage mechanism of aluminum alloys under simulated seawater immersion environment proposed in this embodiment organically combines macroscopic experiments, microscopic characterization and atomic-scale calculations. It can systematically reveal the complete mechanism by which intermetallic compound particles induce pitting corrosion of aluminum alloys through internal complex electrical couples, providing a theoretical basis for the composition design and process optimization of high corrosion-resistant aluminum alloys.

[0060] Example 2 Figure 12 This is a structural diagram of an analysis system for simulating the pitting corrosion damage mechanism of aluminum alloys under seawater immersion environment, according to an embodiment of this application. Figure 12 As shown, the system includes: The determination module 100 is used to determine the phase composition of the target intermetallic compound particles that induce pitting corrosion in the aluminum alloy sample. The construction module 200 is used to prepare pure phase samples of each single phase according to the phase composition, and to construct a coupling system model of each single phase and the aluminum matrix. The characterization module 300 is used to conduct a simulated full seawater immersion corrosion test on the aluminum alloy sample and the coupled system model, and to perform multi-scale electrochemical characterization to obtain the differences in electrochemical activity of each phase. The seawater is a 3.5% NaCl solution by mass.

[0061] The calculation module 400 is used to perform first-principles calculations based on density functional theory based on the phase composition to obtain the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase. The comparative analysis module 500 is used to compare and analyze the differences in electrochemical activity of each phase with the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase, so as to determine the micro-couple mechanism of pitting corrosion induced by the target intermetallic compound particles.

[0062] In this embodiment of the disclosure, the determining module 100 is further configured to: The analytical locations of the target intermetallic compound particles on the surface of the aluminum alloy sample were determined using scanning electron microscopy. The phase composition of the target intermetallic compound particles was obtained at the analysis location using electron backscatter diffraction.

[0063] In this embodiment of the disclosure, the construction module 200 is further configured to: Bulk pure phase samples of each single phase were prepared by spark plasma sintering technology. Aluminum powder was used to simulate the aluminum alloy matrix. Bulk pure phase samples of each single phase were sintered with aluminum powder by spark plasma sintering technology to construct a coupling system model of each single phase and the aluminum matrix.

[0064] Furthermore, the building module 200 is also used for: X-ray diffraction was used to verify the phase structure of the prepared single-phase bulk pure-phase sample.

[0065] In this embodiment of the disclosure, the characterization module 300 is further configured to: The potential distribution of each phase region on the surface of the coupled system model relative to the aluminum substrate was measured using scanning Kelvin probe technology. The local current density distribution on the surface of the coupled system model was monitored using scanning vibration electrode technology; Electrochemical impedance spectroscopy was performed on a single-phase sample, and the charge transfer resistance parameters were obtained by equivalent circuit fitting. The differences in electrochemical activity of each phase are obtained based on the potential distribution, local current density distribution, and charge transfer resistance parameters.

[0066] In this embodiment of the disclosure, the computing module 400 is further configured to: The exposed surfaces of each phase were selected based on the results of electron backscatter diffraction and X-ray diffraction. The surface energy of the selected exposed surface was calculated using VASP software and the PBE-GGA exchange-correlation functional. Calculate the adsorption energies of oxygen and chloride ions on the exposed surfaces of each phase; Calculate the electron localization function of each phase in bulk; Calculate the charge density difference at the heterojunction interface between each phase and the aluminum matrix; Based on the surface energy, adsorption energy, electronic localization function, and charge density difference, the surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics of each phase are obtained.

[0067] In this embodiment of the disclosure, the comparison analysis module 500 is further configured to: Based on the potential distribution and local current density distribution in the electrochemical activity differences, the cathode or anode properties of each constituent phase of the target intermetallic compound particles are determined. The determined cathode or anode properties are verified based on the surface stability, reactivity, bulk structure stability, and interfacial charge transfer characteristics. When the determined cathode or anode properties are consistent with the verification results, the micro-electrical couples formed between each anode phase and the aluminum substrate, and between each cathode phase and the aluminum substrate, are determined according to the direction of electron loss or enrichment in the interface charge transfer characteristics.

[0068] In summary, the analytical system proposed in this embodiment for simulating the pitting corrosion damage mechanism of aluminum alloys under seawater immersion environment organically combines macroscopic experiments, microscopic characterization, and atomic-scale calculations. It can systematically reveal the complete mechanism by which intermetallic compound particles induce pitting corrosion in aluminum alloys through complex internal electrical couples, providing a theoretical basis for the composition design and process optimization of high corrosion-resistant aluminum alloys.

[0069] Example 3 To implement the above embodiments, this disclosure also proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in Embodiment 1.

[0070] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0071] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0072] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An analytical method for simulating the pitting corrosion damage mechanism of aluminum alloys under seawater immersion conditions, characterized in that, The method includes: Determine the phase composition of the target intermetallic compound particles that induce pitting corrosion in aluminum alloy samples; Pure phase samples of each single phase were prepared according to the phase composition, and a coupling system model of each single phase and the aluminum matrix was constructed. A simulated full-immersion corrosion test in seawater was conducted on the aluminum alloy sample and the coupled system model, and multi-scale electrochemical characterization was performed to obtain the differences in electrochemical activity of each phase. First-principles calculations based on density functional theory were performed on the phase composition to obtain the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase. By comparing and analyzing the differences in electrochemical activity of each phase with the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase, the micro-couple mechanism of pitting corrosion induced by the target intermetallic compound particles was determined.

2. The method as described in claim 1, characterized in that, The determination of the phase composition of the target intermetallic compound particles that induce pitting corrosion in the aluminum alloy sample includes: The analytical locations of the target intermetallic compound particles on the surface of the aluminum alloy sample were determined using scanning electron microscopy. The phase composition of the target intermetallic compound particles was obtained at the analysis location using electron backscatter diffraction.

3. The method as described in claim 1, characterized in that, The preparation of pure-phase samples of each single phase according to the phase composition, and the construction of coupling system models of each single phase and the aluminum matrix, include: Bulk pure phase samples of each single phase were prepared by spark plasma sintering technology. Aluminum powder was used to simulate the aluminum alloy matrix. Bulk pure phase samples of each single phase were sintered with aluminum powder by spark plasma sintering technology to construct a coupling system model of each single phase and the aluminum matrix.

4. The method as described in claim 3, characterized in that, X-ray diffraction was used to verify the phase structure of the prepared single-phase bulk pure-phase sample.

5. The method as described in claim 1, characterized in that, The seawater was a 3.5% NaCl solution by mass.

6. The method as described in claim 5, characterized in that, The multi-scale electrochemical characterization to obtain the differences in electrochemical activity of each phase includes: The potential distribution of each phase region on the surface of the coupled system model relative to the aluminum substrate was measured using scanning Kelvin probe technology. The local current density distribution on the surface of the coupled system model was monitored using scanning vibration electrode technology; Electrochemical impedance spectroscopy was performed on a single-phase sample, and the charge transfer resistance parameters were obtained by equivalent circuit fitting. The differences in electrochemical activity of each phase are obtained based on the potential distribution, local current density distribution, and charge transfer resistance parameters.

7. The method as described in claim 6, characterized in that, The first-principles calculations based on density functional theory, performed on the phase composition, yield the surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics of each phase, including: The exposed surfaces of each phase were selected based on the results of electron backscatter diffraction and X-ray diffraction. The surface energy of the selected exposed surface was calculated using VASP software and the PBE-GGA exchange-correlation functional. Calculate the adsorption energies of oxygen and chloride ions on the exposed surfaces of each phase; Calculate the electronic localization function of each phase in bulk; Calculate the charge density difference at the heterojunction interface between each phase and the aluminum matrix; Based on the surface energy, adsorption energy, electronic localization function, and charge density difference, the surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics of each phase are obtained.

8. The method as described in claim 1, characterized in that, The method involves comparing and analyzing the differences in electrochemical activity among the various phases with their surface stability, reactivity, bulk structural stability, and interfacial charge transfer characteristics to determine the microscopic electrocoupler mechanism of pitting corrosion induced by the target intermetallic compound particles. This includes: Based on the potential distribution and local current density distribution in the electrochemical activity differences, the cathode or anode properties of each constituent phase of the target intermetallic compound particles are determined. The determined cathode or anode properties are verified based on the surface stability, reactivity, bulk structure stability, and interfacial charge transfer characteristics. When the determined cathode or anode properties are consistent with the verification results, the micro-electrical couples formed between each anode phase and the aluminum substrate, and between each cathode phase and the aluminum substrate, are determined according to the direction of electron loss or enrichment in the interface charge transfer characteristics.

9. An analytical system for simulating the pitting corrosion damage mechanism of aluminum alloys under seawater immersion environment, characterized in that, The system includes: The determination module is used to determine the phase composition of the target intermetallic compound particles that induce pitting corrosion in aluminum alloy samples. A construction module is used to prepare pure phase samples of each single phase according to the phase composition, and to construct a coupling system model of each single phase and the aluminum matrix. The characterization module is used to simulate full seawater immersion corrosion tests on aluminum alloy samples and the coupled system model, and to perform multi-scale electrochemical characterization to obtain the differences in electrochemical activity of each phase. The calculation module is used to perform first-principles calculations based on density functional theory based on the phase composition to obtain the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase. The comparative analysis module is used to compare and analyze the differences in electrochemical activity of each phase with the surface stability, reactivity, bulk structural stability and interfacial charge transfer characteristics of each phase, so as to determine the micro-couple mechanism of pitting corrosion induced by the target intermetallic compound particles.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-8.

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