Quantitative evaluation method and device for mechanical behavior of material under action of external medium

Abstract

The invention discloses a quantitative evaluation method and device for mechanical behaviors of a material under the action of an external medium. Relates to the technical field of material mechanical behavior testing and evaluation. The method comprises the following steps: preparing a to-be-detected metal material sample, and carrying out surface treatment on the to-be-detected metal material sample. And performing in-situ monitoring and loading test on the sample under the action of an external medium, and collecting deformation response and damage event information of the metal material sample to be detected. And establishing a basic quantitative relationship according to the deformation response and the damage event information, and performing surface stress inversion to obtain an equivalent surface stress result. And based on the coupling relationship of multiple external media, calculating the mechanical behavior evaluation index induced by the external media according to a result corresponding to the equivalent surface, and obtaining a quantitative evaluation result of the metal material sample to be detected under the action of the external media. According to the method, the deformation and fracture mechanism of an engineering material under the action of an external medium can be disclosed, and necessary method support and technical foundation are provided for related engineering application.

Description

Technical Field

[0001] This invention relates to the field of material mechanical behavior testing and evaluation technology, and in particular to a method and apparatus for quantitative evaluation of material mechanical behavior under the action of an external medium. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] During precision machining and service, engineering materials are easily affected by various external media, such as chemical media, electric fields, and stress fields. These external media can significantly alter the stress distribution, defect evolution, and deformation mechanisms on the material surface, thereby affecting the material's plastic deformation capacity, fracture mode, and mechanical properties.

[0004] Traditional methods for evaluating the mechanical behavior of materials mainly involve subjecting standard tensile or fracture mechanics specimens to slow tensile or fatigue loading under specific media and temperature conditions, and evaluating the material's environmental sensitivity through macroscopic indicators such as fracture toughness and crack propagation rate. These methods often require the preparation of specimens with pre-existing cracks or specific geometries, involve large loading devices and long testing cycles, and typically only yield macroscopic failure results. Existing methods struggle to sensitively monitor energy-induced initial microscopic surface damage and surface stress changes in materials; for example, they lack quantitative measurement methods for key mechanistic parameters such as minute elastic-plastic deformations of the surface.

[0005] With the continuous development of precision machining technology and external energy field control methods, there is currently a lack of a quantitative evaluation method for the surface mechanical behavior of materials under in-situ testing in response to external media. Existing methods lack universal applicability to different media conditions, cannot form a comparable and transferable evaluation index system, and cannot provide a unified and powerful quantitative basis for optimizing processing parameters and studying media-sensitive mechanical behavior. In addition, since the mechanical properties of materials exhibit different responses to changes in external media such as chemical media and electric fields, existing methods also struggle to establish a clear quantitative correlation between external media property parameters and the microscopic deformation and mechanical response of the material surface, affecting the directional adjustment and predictable control of the macroscopic mechanical response of the material by the external media. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and apparatus for quantitatively evaluating the mechanical behavior of materials under the influence of external media. This method can quantitatively characterize the effects of factors such as surface stress on the plastic deformation and mechanical properties of materials under different external media, including electric fields, chemical media, and stress fields. This establishes a quantitative evaluation system for mechanical behavior applicable to different engineering materials and under different external media conditions. Furthermore, it can be used for the design of inverse material properties based on external media parameters and the targeted control of macroscopic mechanical behavior. This invention not only helps to reveal the deformation and fracture mechanisms of engineering materials under the influence of external media but also provides necessary methodological support and technical foundation for related engineering applications.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: The first aspect of this invention provides a method for quantitatively evaluating the mechanical behavior of materials under the action of an external medium, comprising the following steps: Prepare a sample of the metallic material to be tested and perform surface treatment on the sample; In-situ monitoring and loading tests are performed on the samples under the action of external media to collect information on the deformation response and damage events of the metal material samples under test. A basic quantitative relationship is established based on the deformation response and damage event information, and surface stress inversion is performed to obtain the equivalent surface force result. Based on the coupling relationship of multiple external media, the evaluation index of the mechanical behavior induced by the external media is calculated according to the equivalent surface force, and the quantitative evaluation result of the metal material sample under test under the action of the external media is obtained.

[0008] Furthermore, the surface treatment of the metal material sample to be tested involves performing a medium-sensitization treatment on at least one surface of the metal material sample to be tested, forming a surface state for external medium response.

[0009] Furthermore, the specific steps of the medium-sensitization process include: constructing a molecular adsorption layer on the surface of the metal material sample to be tested by self-assembling a molecular layer, surfactant, organic or inorganic thin film; preparing a porous metal sample by selective corrosion through electrochemical means, and placing the porous metal sample in an electrolyte-wetted state.

[0010] Furthermore, the external medium includes at least one of the following: a mechanochemical medium or an electrochemical medium. The mechanochemical medium is used to induce the formation and stabilization of the molecular adsorption layer, and a chain length variable group is constructed by changing the organic molecular chain length parameter. Different organic molecular chain lengths correspond to different mechanical response differences. The electrochemical medium is the electric field and chemical electrochemical environment for generating porous metal samples and testing material properties.

[0011] Furthermore, in-situ monitoring and loading tests of samples under the influence of external media include in-situ monitoring under the influence of mechanical and chemical media, as well as loading tests under the influence of electrochemical media.

[0012] Furthermore, the specific steps for in-situ monitoring under the influence of mechanical and chemical media include: The deflection and shape changes of the free end of the cantilever are measured using an optical microscope, laser displacement sensor, interferometer, or capacitive displacement sensor. Local strain fields are measured using strain gauges, fiber optic gratings, or digital imaging. Microcrack initiation and propagation events can be monitored using acoustic emission sensors or high-frequency force sensors. The variation characteristics of the deformation removal mode of the material under mechanical bias loading were observed using a high-speed camera and in-situ digital images.

[0013] Furthermore, the specific steps for performing compression loading tests under the action of an electrochemical medium include: Obtain in-situ characterization under the influence of electrochemical media; In-situ compression loading was performed under the action of an electrochemical medium based on the obtained in-situ characterization.

[0014] Furthermore, the results of equivalent surface force include time-varying results of equivalent surface stress and time-varying results of equivalent surface driving force. Equivalent surface stress is calculated from deflection signal, and time-varying results of equivalent surface driving force are used to characterize the driving force of surface stress on deformation or damage, including two types of driving force: load-type driving force and strength-type driving force.

[0015] Furthermore, based on the coupling relationship of multiple external media, the specific steps for calculating the evaluation index of the mechanical behavior induced by the external media according to the equivalent surface force are as follows: Set general metrics; The chain length effect of the interaction pathway between mechanical and chemical media is evaluated based on the set general indicators. The mechanical properties of the electrochemical field medium are controlled and evaluated based on the established general indicators.

[0016] The second aspect of the present invention provides a quantitative evaluation device for the quantitative evaluation method of material mechanical behavior under the action of an external medium in the first aspect, including a mechanochemical effect testing device and an electrochemical effect testing device.

[0017] The above one or more technical solutions have the following beneficial effects: This invention discloses a method and apparatus for quantitatively evaluating the mechanical behavior of materials under the influence of external media. It mainly includes two types of media effects: the first is mechanochemical media effect, which involves constructing an adsorption layer film on the material surface and changing the molecular chain length to control the equivalent surface stress and embrittlement sensitivity index; combined with cantilever beam deflection inversion and mechanical response verification, a mapping relationship between the external media properties and the material deformation mode is established. The second is electrochemical media effect, which involves preparing nanoporous metal samples and introducing them into an electrolyte wetting process. In-situ compression tests are then conducted under an applied electric field to obtain the variation laws of yield strength, flow stress, and ductility parameters under different electric field intensities, constructing a quantitative evaluation index for reversibly controllable electric field-mechanical properties. Compared with existing technologies, this invention does not require pre-fabricated cracks or large-scale experimental equipment, and can perform highly sensitive in-situ measurements and unified quantitative evaluations of the surface mechanical response of materials under the influence of external media, providing methodological support for the study of the influence of external media on the mechanical behavior of materials.

[0018] This invention utilizes micro-cantilever beam deflection, local strain field, and acoustic emission signals to achieve in-situ, continuous monitoring of surface stress and damage evolution of materials under the influence of external media, which is more sensitive and faster than traditional macroscopic experiments.

[0019] The method of this invention is applicable to coupling environments of single or multiple external energy fields and media (electric field, chemical medium, stress field, etc.), and can obtain unified evaluation parameters for different material / media combinations, thus broadening the application scope of the study of material mechanical behavior under the influence of external media.

[0020] This invention can quantitatively describe the plastic-brittle transition induced by mechanical and chemical media and the mechanical properties regulated by electric field strength under electrochemical conditions. For example, it can measure surface stress changes of tens of N / m caused by adsorption layers and reveal the quantitative relationship between this change and the macroscopic mechanical properties of materials (such as cutting force); it can characterize the entire process and hysteresis effect of the reversible regulation of flow stress in porous metal samples with potential under the action of an electric field.

[0021] This invention proposes a series of indicators such as surface stress peak and embrittlement index, which can be compared across different media and materials. It establishes a quantitative evaluation basis for media-assisted fracture sensitivity, rather than just a qualitative description, which is convenient for engineering applications.

[0022] The evaluation results obtained by this invention can be used for reverse design of external medium action parameters and optimization of processing technology. For example, by selecting appropriate surfactant chain length, medium conditions and potential levels, the macroscopic mechanical response of materials can be directionally controlled, reducing processing energy consumption, improving surface quality and reducing the risk of material failure caused by external medium action.

[0023] Advantages of additional aspects of the invention 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 the invention. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating the overall implementation of the quantitative evaluation method and device for the mechanical behavior of materials under the action of an external medium, as described in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of an in-situ test of a cantilever beam device for measuring surface stress of an organic monolayer under the action of a mechanochemical medium, according to Embodiment 1 of the present invention. In the diagram, (a) is a front view, showing the in-situ test of the cantilever beam with an untreated surface; (b) is a front view, showing the in-situ test of the cantilever beam with a treated surface; (c) is a top view, showing the in-situ test of the cantilever beam with an untreated surface; and (d) is a top view, showing the in-situ test of the cantilever beam with a treated surface. Figure 3 This is a schematic diagram of the preparation and in-situ compression test of porous metal samples under the action of an electrochemical medium in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the organic monolayer preparation process under the action of a mechanochemical medium in Embodiment 1 of the present invention; Figure 5 The figures show the changes in the microscopic deformation of the cantilever beam over time and the changes in the length of the monolayer molecular chain and the surface stress under the action of the mechanochemical medium in Embodiment 1 of the present invention. (a) is a graph of the microscopic deformation of the cantilever beam over time, and (b) is a graph of the changes in the length of the monolayer molecular chain and the surface stress. Figure 6 This is a cyclic voltammogram and mechanical property test under the action of an electrochemical medium in Embodiment 1 of the present invention, wherein (a) is a cyclic voltammogram under the action of an electrochemical medium, and (b) is a compressive stress-strain curve under different voltages; Figure 7 The mechanical property test curves of organic monolayer film and untreated sample under the action of mechanochemical medium in Embodiment 1 of the present invention are shown. Among them, (a) is the microhardness variation diagram of organic monolayer film and untreated sample at different depths, and (b) is the strain distribution diagram of organic monolayer film and untreated sample at different depths. Detailed Implementation

[0026] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0028] Example 1: Embodiment 1 of the present invention provides a method for quantitatively evaluating the mechanical behavior of materials under the action of external media, such as... Figure 1 As shown, it includes the following steps: S1: Prepare the metal material sample to be tested and perform surface treatment on the metal material sample to be tested.

[0029] S1.1: Select the metal material sample to be tested.

[0030] In one specific embodiment, the material to be tested is selected and prepared as a beam-shaped, thin plate-shaped, or sheet-shaped sample, preferably a cantilever structure with one end fixed and the other end free. In this embodiment, the length of the metal material sample to be tested is 200 mm, the thickness is 0.2 mm, and the height is 10 mm.

[0031] The external medium includes at least one of the following: a mechanochemical medium or an electrochemical medium. The mechanochemical medium is used to induce the formation and stabilization of the molecular adsorption layer, and a chain length variable group is constructed by changing the organic molecular chain length parameter; different organic molecular chain lengths correspond to different mechanical response differences. The electrochemical medium is the electric field and chemical electric field environment for generating porous metal samples and testing material properties. The steps of loading and testing in the electrochemical medium environment include: preparing porous metal samples and wetting them with electrolyte, applying different potentials or equivalent electric field strengths, and performing in-situ compression or equivalent mechanical loading tests to obtain stress-strain responses under different electric field conditions.

[0032] S1.2: At least one surface of the metal material sample to be tested is subjected to a medium-sensitization treatment to form a surface state for external medium response.

[0033] In one specific embodiment, a localized surface treatment is performed on one side of the sample to form an environmentally sensitive surface layer. The thickness of the surface layer is preferably 500 nm to 1 μm to ensure that it has a significant impact on surface stress without significantly changing the overall stiffness of the sample.

[0034] A beeswax layer is applied to all areas opposite to the localized surface treatment of the sample to facilitate observation of microscopic deformation under the influence of external media. Media sensitization treatment includes, but is not limited to: constructing a molecular adsorption layer on the surface of the metal sample to be tested through self-assembled molecular layers, surfactants, or organic / inorganic thin films; preparing porous metal samples by selective etching through electrochemical means, and placing the porous metal samples in an electrolyte-wetting state.

[0035] More specifically, in surface treatment involving mechanical and chemical media, it is preferable to first perform plasma cleaning on the sample surface to increase the density of surface active sites. Then, the sample is immersed in a solution containing a linear organic molecular precursor for a certain period, allowing it to self-assemble into a molecular adsorption layer on the metal surface. For molecules with silane functional groups, the surface can be pre-activated; for organic acid molecules, a monolayer can be formed directly in the corresponding alcohol solution. After treatment, the formation state of the molecular layer can be verified by contact angle, film thickness, or equivalent methods. Mechanical and chemical media utilize varying molecular chain length parameters to construct a chain length variable set, thereby creating differences in mechanical responses corresponding to different chain lengths.

[0036] More specifically, in surface treatment using electrochemical media, metal or alloy systems capable of forming porous structures are selected, and porous metal samples are prepared through selective chemical or electrochemical dissolution. Characteristic dimensions of porous structures. The relative density can be controlled within the range of 50–500 nm. The pore size is controlled between 0.1 and 0.6; porous metal samples are prepared into geometries suitable for compression loading (e.g., columnar or blocky), and their initial dimensions and pore structure parameters are recorded. , This serves as a reference standard. Subsequently, the sample is fully immersed in the electrolyte, allowing the electrolyte to continuously fill the pores, providing a basis for in-situ compression tests under the influence of the electric field medium.

[0037] S2: In-situ monitoring and loading tests are performed on the sample under the action of external medium to collect information on the deformation response and damage events of the metal material sample under test.

[0038] In one specific implementation, the deformation response includes at least one of displacement, deflection, or strain field.

[0039] Damage events include, but are not limited to, crack initiation and crack propagation events. In-situ monitoring under mechanical and chemical media involves observing the deformation process of a monomolecular adsorbed layer cantilever beam. In-situ testing under electrochemical media involves testing the mechanical properties of nanoporous metal structures in situ.

[0040] More specifically, in-situ monitoring is conducted under the influence of mechanical and chemical media. This includes in-situ observation of cantilever beam deformation testing, in-situ monitoring of mechanical behavior, and mechanical loading response testing.

[0041] (1) In-situ observation of cantilever beam deformation test mechanical behavior in situ monitoring.

[0042] A molecular adsorption layer will form on the side of the surface treated under the action of a chemical medium. Then, the surface-treated sample is placed under the action of the chemical medium for in-situ monitoring. The steps include: The deflection and shape changes of the free end of the cantilever are measured using an optical microscope, laser displacement sensor, interferometer, or capacitive displacement sensor. Local strain fields are measured using strain gauges, fiber optic gratings, or digital image correlation techniques. Microcrack initiation and propagation events can be monitored using acoustic emission sensors or high-frequency force sensors. The variation characteristics of the deformation removal mode of the material under mechanical bias loading were observed using a high-speed camera and in-situ digital image correlation technology.

[0043] (2) Mechanical loading response test The variation characteristics of material deformation removal modes under mechanical bias loading were observed using high-speed cameras and in-situ digital image correlation techniques. The parameters for mechanical property testing were expanded to include material stress-deformation and material deformation modes.

[0044] Specifically, in-situ digital image-related mechanical loading response verification experiments were conducted to obtain the strain field evolution and force signal characteristics under the action of external media, and mechanical loading response indices were constructed based on the force signal changes.

[0045] The mechanical loading response index includes the force signal normalization coefficient, which satisfies: .

[0046] in, F max ( l ( ) is the chain length l Send the maximum force signal. F max (0) represents the maximum force signal on the unprocessed surface.

[0047] More specifically, loading tests are performed under the influence of an electrochemical medium. The steps include: (1) In-situ characterization setup under the action of electrochemical media.

[0048] An electrochemical control system (e.g., a three-electrode system of electrode / reverse electrode / working electrode) is established, with the porous metal sample used as the working electrode, and the electrolyte temperature controlled between 0 and 80 °C. Electrochemical scanning or step potential testing is performed on the sample to determine the potential window and characteristic potential range, obtaining cyclic voltammetry curves. At least two potential levels are selected within the potential window. First potential 1: Corresponding to specific adsorption / double layer dominant regions on the corresponding surface; Second potential 2: Corresponding to regions where the adsorption state on the surface changes significantly (e.g., the appearance of adsorption / desorption plateaus or peak regions). The potential holding time is preferably 10s to 60min to allow the surface state to reach a quasi-steady state.

[0049] (2) Porous metals are subjected to in-situ compression loading under the action of electrochemical media.

[0050] Maintaining the specified potential Simultaneously, in-situ compression loading is performed, using either displacement-controlled or force-controlled loading; the strain rate is controlled at 10. -4 ~10 -2 s -1 Within the specified range. Record the engineering stress-strain curve and extract the yield strength. s y ( E ), flow stress s ( e , E Plastic limit strain e f ( E ).

[0051] S3: Establish a basic quantitative relationship based on the deformation response and damage event information, and perform surface stress inversion to obtain the equivalent surface force result.

[0052] S3.1: Establish a basic quantitative relationship based on deformation response and damage event information.

[0053] In one specific implementation, based on the sample material parameters, geometric dimensions, and measured deflection or strain data, the relationship between equivalent surface stress and deflection / curvature is established using thin plate / beam bending theory, thereby obtaining surface stress variation curves under different times and different external medium conditions.

[0054] The equivalent surface stress is obtained by converting the deflection signal, and the calculation formula is as follows: .

[0055] in, s s ( t () represents the equivalent surface stress. ( ) is a characterization quantity for the deflection or equivalent curvature of the free end of the specimen. The conversion factor is obtained by calibrating the elastic and geometric parameters of the specimen.

[0056] Preferably, for cantilever beams, the relationship between surface stress and deflection is calculated using the following formula: .

[0057] in, f For surface stress, Δ h It is the deflection at the free end of the cantilever beam. E y For Young's modulus, n Poisson's ratio, t For the thickness of the cantilever beam, L c The length of the cantilever beam is given; thus, surface stress variation curves under different time and chemical medium conditions are obtained.

[0058] S3.2: Based on the collected deformation response and the geometric and material parameters of the specimen, the equivalent surface force is obtained by inversion. The equivalent surface force results include the time-varying results of the equivalent surface stress and the time-varying results of the equivalent surface driving force. The equivalent surface stress is calculated from the deflection signal. The time-varying results of the equivalent surface driving force are used to characterize the driving force of surface stress on deformation or damage, including two types of driving forces: load-type driving force and strength-type driving force.

[0059] Specifically, under the influence of an external medium, because the molecular thin film forms an adsorption layer only on one side of the sample surface (the other side is isolated by a beeswax mask), an unbalanced surface stress is generated in the thickness direction, thereby driving a measurable end deflection in the cantilever beam. h ( t Under the assumptions of small deflection and linear elasticity, the collected data are analyzed based on the Stoney relation for thin beam bending. h ( t ) and the geometric parameters of the specimen (length) L Thickness t, width b) and material parameters (Young's modulus) E y Poisson's ratio v Establish the corresponding conversion relationship, and directly calculate the time-varying result of the equivalent surface stress using the above formula. f ( t The load-type driving force is obtained by integrating over the width of action to obtain the equivalent surface force. F s ( tThis is to correspond to external loads or structural responses. F s ( t )= f ( t ) b The strength-type driving force is to f ( t Combined with equivalent surface thickness d s Converted to equivalent surface driving force or equivalent stress characterization s eq ( t This process generates a time-varying inversion result from deformation response to equivalent surface force (stress / driving force), which can be directly used for damage events and fracture / plasticity criteria, providing input for subsequent calculation of evaluation indicators of externally induced mechanical behavior. s eq ( t )= f ( t ) / d s .

[0060] S4: Based on the coupling relationship of multiple external media, the mechanical behavior evaluation index induced by the external media is calculated according to the equivalent surface force, and the quantitative evaluation result of the metal material sample under test under the action of the external media is obtained.

[0061] In one specific implementation, based on the obtained material surface stress-deformation-damage data, one or a combination of multiple evaluation indicators are constructed to output quantitative evaluation results of the mechanical behavior induced by the external medium.

[0062] In this embodiment, the material surface stress-deformation-damage data includes: the results of equivalent surface force; deformation response data such as deflection, curvature, and strain; damage event data such as crack initiation time and crack length, and corresponds to the sample material parameters, geometric parameters, and external medium condition parameters.

[0063] S4.1: Set general metrics.

[0064] Specifically, it includes: The peak surface stress and its variation with external medium parameters (temperature, chemical composition, electric field / potential, etc.).

[0065] The crack initiation delay time or crack propagation rate at a given surface stress level.

[0066] Embrittlement sensitivity index (e.g., characterized by the number of crack events per unit energy input or unit displacement, deflection fluctuation amplitude, etc.) reflects the transition from stable plastic deformation to periodic fracture.

[0067] Failure risk levels are determined based on different surface treatment methods and different external media conditions.

[0068] S4.2: Evaluate the chain length effect of the interaction pathway between mechanical and chemical media based on the set general indicators.

[0069] Chain length variables refer to the set of variables that change only the carbon chain length (or equivalent chain length parameter, such as C) of the adsorbed organic molecules under mechanical and chemical media. n In n ( ), while others remain consistent, forming a set of control samples. For example Figure 5 (b) is a curve showing the relationship between the length of a single-layer molecular chain and surface stress. Straight-chain molecules with different chain lengths of C2, C5, C8, C16, and C20 were selected to form molecular adsorption layers on the same metal surface, and the corresponding deflection and inverted surface stress were measured. This group of samples arranged in ascending order of carbon chain length is called the chain length variable group.

[0070] The chain length effect refers to the phenomenon where changes in the chain length of organic molecules alter the packing density of the adsorption layer, intermolecular van der Waals interactions, orientational order, film thickness and stiffness, and the strength of interactions with the metal surface, thereby changing the steady-state equivalent surface stress introduced by the adsorption layer on the surface. Figure 5 (a) and Figure 5 As shown in (b), the deformation and surface stress of the cantilever beam will change with different chain lengths.

[0071] Specifically, steady-state equivalent surface stress is obtained by varying the molecular chain length. And define the equivalent surface stress increment related to chain length. : .

[0072] Among them, △ s s ( l () represents the equivalent surface stress increment. ,0 The reference steady-state value for the untreated surface. ,sat ( l (The chain length is) l The steady-state equivalent surface stress.

[0073] Furthermore, evaluation quantities related to chain length, such as the material embrittlement sensitivity index and deformation force normalization coefficient, can be constructed to achieve quantitative prediction and control of material deformation behavior (ductile-brittle transition, material deformation characteristics, and force response).

[0074] Construct an embrittlement sensitivity index to characterize the ductile-brittle transition mode induced by mechanical and chemical media, satisfying: .

[0075] Among them, B( l ) represents the embrittlement sensitivity index, Δ s s ( l () represents the equivalent surface stress increment. ,0 It is the material's reference yield strength (or equivalent yield parameter). ( () represents the number of crack events per unit displacement or per unit time. 0 is the normalization constant.

[0076] Deformation mode transitions under mechanochemical conditions are characterized by a threshold criterion that satisfies: .

[0077] in, ,crit The critical equivalent surface stress threshold is obtained through multiple chain length and control experiments. When the above relationship is satisfied, the material removal or deformation mode is determined to be either brittle-dominated or plastic removal mode.

[0078] S4.3: Evaluate and regulate the mechanical properties of the electrochemical field medium based on the set general indicators.

[0079] S4.3.1: Calculate the electric field modulation intensity coefficient.

[0080] An electric field modulation intensity coefficient is defined to characterize the extent to which the electric field modulates the intensity or flow stress, and is obtained based on different potentials E. s y ( E ), s ( e , E )and e f ( E The electric field control coefficient is established as follows: .

[0081] in, S E ( e ) represents the electric field modulation intensity coefficient. s ( e , E 0) represents the flow stress at the initial strain. E 0 is the reference potential. s ( e , E ) represents the flow stress at a given strain.

[0082] S4.3.2: Calculate the electric field-induced ductility change index of the material.

[0083] .

[0084] in, D E As an index of electric field-induced ductility change, Potential E The plastic limit strain or instability strain below, It is the reference potential. E The plastic limit strain or instability strain measured under 0 conditions.

[0085] S4.3.3: Calculate the comprehensive controllability index based on the electric field control intensity coefficient and the electric field-induced material ductility change index.

[0086] .

[0087] in, T E To provide a comprehensive and adjustable index, 1 and 2 is a weighting coefficient, set according to engineering application requirements (ductility is prioritized for processing and forming, and strength is prioritized for service load bearing).

[0088] S4.3.4: Reversible control verification is performed by controlling the step potential or by cyclic switching. Taking the step potential method as an example, the process is performed on the same sample. E 1- E 2- E The process is repeated 1 time, with small-strain compressive loading applied at each potential segment. The reversibility and stability of the electric field control are evaluated by comparing whether the changes in flow stress in each segment can be repeatedly recovered.

[0089] S4.3.5: Perform optional response function fitting operation.

[0090] .

[0091] in, s y ( E ) represents the fitted response function. 1 and 2 represents the fitting parameters. E 0 is the reference potential. E 0 represents the set potential and can be further used as a pore size. With relative density The function is used to form a structure-electric field-mechanical property coupled database.

[0092] This embodiment uses a selectable response function fitting method to represent the mechanical response (such as yield strength as a function of potential) obtained at discrete potential points in the experiment as a continuous, computable, and parameterizable function, which can be used for interpolation and prediction at arbitrary potentials. The electric field sensitivity of different samples is compared, and the fitting parameters are further compared with structural parameters (pore size). L relative density r This establishes a correlation, forming a coupled database of "structure-electric field-mechanical properties," which supports subsequent optimization and reversibility evaluation of potential selection, step / cyclic switching control strategies. The optional response function in this embodiment includes at least the potential-yield strength response function.

[0093] By comparing the above indicators with traditional parameters such as tensile strength, hardness, and fracture toughness, a comprehensive evaluation system for the mechanical behavior of materials in multi-energy field media is established.

[0094] S4.4: Apply the results based on the evaluation.

[0095] In one specific implementation, the evaluation results can be used for screening external medium systems, optimizing processing parameters under the influence of external media, controlling the material's medium-sensitive mechanical behavior, and risk assessment.

[0096] Specifically, based on the evaluation results obtained, it may be used for one or more of the following: Select coolant, lubricant, or surfactant system to achieve external medium-assisted cutting or grinding process design.

[0097] Optimize material surface treatment processes (such as chemical / electrochemical porous layers and coating design) to reduce the risk of material failure under the influence of media.

[0098] Predict and classify the failure risks of critical components under service conditions.

[0099] To better illustrate the superiority of this method, two specific examples are given for detailed explanation: evaluation of surface stress and embrittlement effects of copper alloys under mechanochemical conditions, and regulation of the mechanical properties of nanoporous metals under electrochemical media. The specific steps are as follows: Example 1: Evaluation of surface stress and embrittlement effect of copper alloys under mechanochemical conditions.

[0100] Step 1: Sample preparation and surface treatment.

[0101] Two types of samples are prepared from the selected metallic material to be tested (preferably a ductile metal or alloy, such as aluminum alloy or copper alloy): Cantilever beam specimen: length 200 mm, width 10 mm, thickness 0.2 mm; The test specimen for the bias mechanical loading verification is a plate-shaped or block-shaped workpiece with a thickness of 0.2 to 1 mm. The surface roughness of the specimen to be subjected to bias mechanical loading is preferably Ra≤0.1μm.

[0102] The above samples were subjected to surface pretreatment, including degreasing, cleaning, and drying; if necessary, surface activation (e.g., mild oxidation / plasma cleaning / chemical activation) was performed to improve the stability of the adsorption layer.

[0103] Step 2: Construction of organic monolayers and setting chain length variables.

[0104] like Figure 4 This is a schematic diagram of the organic monolayer preparation process under a mechanochemical environment. The sample surface to be treated is exposed to a medium containing a linear organic molecular precursor, allowing it to self-assemble on the metal surface to form an organic monolayer adsorption layer. The medium can be a solution phase or a vapor phase, the treatment time is 0.5–24 h, and the treatment temperature is 20–80 ℃.

[0105] Changing only the chain length parameter of organic molecules (For example, carbon chain number 3-20), and keep the group head group type, concentration, solvent system, treatment temperature and treatment time consistent to form a chain length variable group. The chain length variable group should contain at least 3 different chain lengths (short chain / medium chain / long chain).

[0106] The formation state of the monolayer is confirmed (by means of contact angle, film thickness or equivalent confirmation method) to obtain the criteria for the completion of monolayer formation (e.g., contact angle stability or film thickness stability).

[0107] Step 3: In-situ measurement of cantilever beam: Quantitative characterization of equivalent surface stress.

[0108] The cantilever beam specimen is fixed to the fixture module, ensuring that one end is fixed and the other end is free; the side with the monolayer faces the mechanochemical environment cavity. Figure 2 This is a schematic diagram of an in-situ test of a cantilever beam apparatus for measuring surface stress in a monolayer under mechanochemical conditions.

[0109] Constructing a mechanochemical medium: Introduce an environment containing adsorbed molecules or solvent vapor / lubricating medium into the environmental cavity, and set the temperature to 20–120 °C; optionally, set the temperature to be constant or to change stepwise to simulate processing or service conditions.

[0110] Figure 5This study presents the microscopic deformation of a cantilever beam over time and the curves showing the relationship between the length of the monolayer molecular chain and surface stress under mechanochemical conditions. Under no external load or a small external load (equivalent load range of 0–5 N), the deflection at the free end of the cantilever was continuously collected using a displacement measurement unit. ( ) and time The relationship curve.

[0111] Based on the material's elastic and geometric parameters, a conversion relationship between deflection and equivalent surface stress is established, and the equivalent surface stress is defined as: .

[0112] in, s ( () represents the equivalent surface stress. b The conversion factor (including parameters such as elastic modulus, moment of inertia, and effective length) is obtained from the beam bending calibration. ( ) represents the free end deflection.

[0113] For different chain lengths The steady-state equivalent surface stress of the sample was obtained. s s ( l ), and define the equivalent surface stress increment related to chain length: .

[0114] Among them, △ s s ( l () represents the equivalent surface stress increment. ,0 The reference steady-state value for the untreated surface. ,sat ( l (The chain length is) l The steady-state equivalent surface stress.

[0115] Step 4: Construction of quantitative indicators for the ductile-brittle transition.

[0116] An embrittlement susceptibility index is constructed using equivalent surface stress increment and crack response: .

[0117] Among them, B( l ) represents the embrittlement sensitivity index, Δ s s ( l () represents the equivalent surface stress increment. ,0 It is the material's reference yield strength (or equivalent yield parameter). ( The number of crack / instability events per unit displacement or per unit time is obtained from acoustic emission abrupt changes, force signal sudden drops, and DIC crack identification. 0 is the normalization constant. When ( The increase in the value indicates an enhanced tendency for environment-induced fracture-dominated removal.

[0118] The ductile-brittle transition criterion is defined as follows: .

[0119] in, ,crit The critical equivalent surface stress threshold is obtained through multiple chain length and control experiments.

[0120] Step 5: Characterization of the mechanical response of a monolayer under mechanochemical effects.

[0121] The normalization coefficient is defined to evaluate the ability of a chemical monolayer to modulate its mechanical response: .

[0122] in, F max ( l ( ) is the chain length l Send the maximum force signal. F max (0) represents the maximum force signal on the unprocessed surface. or F ( l The maximum force signal was normalized and plotted as a function of chain length, and compared with Δσ. s ( l ) and B( l By comparison, a quantitative mapping relationship between "chemical molecular layer - surface stress - material deformation behavior" is established.

[0123] Optional mechanical comparison tests (such as bending / indentation / micro-loading) can be performed to obtain response curves of treated and untreated samples, which can be used to verify that the molecular layer mainly changes the dominant mechanism of material damage and fracture, without significantly changing the elastic stiffness. Figure 7 The mechanical property test curves are shown for organic thin films under mechanochemical media, comparing them with untreated samples.

[0124] Example 2: Regulation of mechanical properties of nanoporous metals in electrochemical media.

[0125] Step 1: Preparation of porous metal samples.

[0126] Porous metals are prepared by selectively dissolving metals or alloys capable of forming porous structures using chemical or electrochemical methods. Characteristic dimensions of porous structures. The relative density can be controlled within the range of 50–500 nm. The value should be controlled between 0.1 and 0.6.

[0127] Porous metal samples are prepared into geometries suitable for compression loading (e.g., columnar or blocky), and their initial dimensions and pore structure parameters are recorded. , () as a benchmark.

[0128] The sample is fully immersed in the electrolyte, allowing the electrolyte to continuously fill the pores and form a metal porous framework-electrolysis composite microstructure.

[0129] Step 2: Electric field loading and electrochemical state characterization.

[0130] Figure 6 Cyclic voltammetry and mechanical property testing under electrochemical conditions were performed. An electrochemical control system (a three-electrode system of reference electrode / counter electrode / working electrode) was established, with the porous metal sample used as the working electrode, and the electrolyte temperature controlled between 0 and 80 °C.

[0131] Electrochemical scanning or step potential testing is performed on the sample to determine the potential window and characteristic potential range, obtaining cyclic voltammetry curves. At least two potential levels are selected within the potential window: First potential 1: Corresponding to specific adsorption / double layer dominant regions on the corresponding surface; Second potential 2: Corresponding to regions of significant change in the adsorption state on the surface (e.g., the appearance of adsorption / desorption plateaus or peak regions). The potential holding time can be 10 s to 30 min to ensure that the surface state reaches a quasi-steady state.

[0132] Step 3: In-situ compression loading and acquisition of mechanical response Figure 3 This diagram illustrates the preparation and in-situ compression testing of porous nanostructured metals in an electrochemical medium. While maintaining a specified potential... Simultaneously, in-situ compression loading is performed, using either displacement-controlled or force-controlled loading; the strain rate is controlled at 10. -4 ~10 -2 s -1 Within the specified range. Record the engineering stress-strain curve and extract the yield strength. s y ( E ), flow stress s ( e , EPlastic limit strain e f ( E ).

[0133] The electric field modulation intensity coefficient is defined as: .

[0134] in, S E ( e ) represents the electric field modulation intensity coefficient. s ( e , E 0) represents the flow stress at the initial strain. E 0 is the reference potential. s y ( E () represents the yield strength. s ( e , E ) represents the flow stress at a given strain.

[0135] The electric field-induced ductility change index is defined as: .

[0136] in, D E As an index of electric field-induced ductility change, This represents the plastic limit strain or instability strain at potential E. It is the reference potential. E The plastic limit strain or instability strain measured under 0 conditions.

[0137] Define a comprehensive adjustable index for material screening: .

[0138] in, S E The electric field modulation intensity coefficient, D E Indices of electric field-induced ductility change 1 and 2 is a weighting coefficient, set according to engineering application requirements (ductility is prioritized for processing and forming, and strength is prioritized for service load bearing).

[0139] Step 4: Verification of reversible control and fitting of response function.

[0140] Reversibility verification was performed using a potential step method: the procedure was carried out on the same sample. E 1- E 2- EThe process involves repeating the cycle 1, applying small-strain compression loading to each potential segment, and comparing whether the changes in flow stress in each segment can be repeatedly recovered, thereby determining the reversible controllability of the mechanical response.

[0141] Optionally, a potential-intensity response function can be established for prediction and engineering applications: .

[0142] in, T E To provide a comprehensive and adjustable index, 1 and 2 represents the fitting parameters. E 0 is the reference potential. E 0 represents the set potential and can be further used as a pore size. With relative density The function is used to form a structure-electric field-mechanical property coupled database.

[0143] Example 2: Embodiment 2 of the present invention provides a quantitative evaluation device for the quantitative evaluation method of material mechanical behavior under the action of external medium in Embodiment 1, including a mechanochemical effect testing device and an electrochemical effect testing device.

[0144] 1. Mechatronic effect testing device: In one specific embodiment, the mechatronic effect testing device of the present invention is a cantilever beam in-situ bending measurement system, comprising a cantilever beam specimen, a clamping and fixing unit, a transparent medium container, and an optical microscopic imaging measurement unit. The cantilever beam specimen is a metal beam-shaped specimen. The clamping and fixing unit clamps one end of the cantilever beam specimen to form a fixed end, leaving the other end suspended to form a free end. The transparent medium container is preferably a glass container, containing a chemical solution as the chemical medium. The clamping and fixing unit and the cantilever beam specimen are integrally arranged within the transparent medium container, so that the cantilever beam specimen is at least partially immersed in the chemical medium. The optical microscopic imaging measurement unit is positioned above the transparent medium container, with its optical path aligned with the free end region of the cantilever beam specimen, for in-situ observation and recording of the displacement / deflection of the free end of the cantilever beam in a chemical medium environment.

[0145] To achieve unilateral adsorption-induced surface stress difference-driven bending, a shielding layer, preferably a beeswax layer, is applied to one side of the cantilever beam specimen to isolate this side from the chemical solution and inhibit the adsorption of organic molecules. The other side of the cantilever beam specimen remains exposed and in direct contact with the chemical solution, forming a thin monolayer under the action of the chemical medium. Due to the asymmetry of the two surface states, the surface stress change generated on the adsorption side is inconsistent with that on the shielded side, thus forming an unbalanced surface stress in the thickness direction of the specimen and driving the cantilever beam to bend.

[0146] The workflow of the mechatronic effect testing device includes: first, cleaning / treating the surface of the cantilever beam sample, and then coating one side of the sample with a beeswax layer to form a shielding layer; subsequently, fixing one end of the sample to the clamping and fixing unit, and placing the clamping and fixing unit and the sample as a whole into a transparent medium container containing a chemical solution, ensuring full contact between the exposed side of the sample and the chemical medium; during the gradual formation of the molecular adsorption layer, the free end of the cantilever beam exhibits a time-varying deflection response. The optical microscopic imaging measurement unit continuously images and records the free end region at preset time intervals, and extracts the free end deflection from the image sequence. h ( t Furthermore, based on the thin beam bending theory and the Stoney relation, h ( t Convert / invert to equivalent surface stress f ( t The time-varying results enable quantitative characterization of the coupled process of "external chemical medium-surface stress-deformation response".

[0147] 2. Electrochemical effect testing device: In one specific implementation, such as Figure 3 As shown, the device for in-situ mechanical testing under the action of an electrochemical field medium in this embodiment includes an electrochemical control unit, a solution loading unit, a three-electrode unit, and an in-situ compression loading unit. The electrochemical control unit is a voltage regulator (potentiostat / electrochemical workstation) used to control the potential and monitor the current of the sample under a set potential condition. The solution loading unit is an electrochemical cell / electrolyte container filled with electrolyte, used to provide an ion conduction environment for the electrochemical reaction and to wet the porous sample. The three-electrode unit includes a working electrode, a reference electrode, and a counter electrode. The working electrode is electrically connected to the porous metal sample, allowing the porous metal sample to participate in electrochemical polarization as the working electrode. The reference electrode is preferably an Ag / AgCl reference electrode, with its terminals immersed in the electrolyte and positioned close to the porous sample to provide a stable reference potential. The counter electrode is immersed in the electrolyte and electrically connected to the voltage regulator, forming a closed current loop with the working electrode. The in-situ compression loading unit includes a diamond anvil cell (or a diamond flat anvil) and its loading mechanism. The porous metal sample is placed between or in contact with the diamond anvil cells. The loading mechanism applies axial pressure to the diamond anvil cells to achieve in-situ compression loading of the porous sample. It is equipped with a force / displacement acquisition module to obtain force-displacement or stress-strain data.

[0148] The workflow of the electrochemical effect testing device includes: First, the porous metal sample is clamped between (or in contact with) the anvils of the in-situ compression loading unit, and the sample is placed in the electrochemical cell, allowing the electrolyte to fully wet the internal pores of the porous structure; then, the three electrodes are arranged and electrically connected, with the porous metal sample connected as the working electrode, the Ag / AgCl reference electrode inserted into the electrolyte and placed close to the sample, and the counter electrode immersed in the electrolyte. All three are electrically connected to the voltage regulator to form an electrochemical closed loop; the voltage regulator applies and maintains a preset potential based on the reference electrode, so that the porous framework-electrolyte interface is in the corresponding electrochemically regulated state; while maintaining the potential, in-situ compression loading is performed, the stress-strain curve is recorded, and the yield strength, flow stress at a given strain, and plastic limit strain or instability strain are extracted. Further, the potential can be switched by step potential or cyclic potential switching (e.g., E 1→ E 2→ E 1) Repeatedly apply small strain loading to the same sample and compare whether the mechanical response at different potential ranges can be repeatedly recovered, thereby evaluating the reversibility and stability of electrochemical field modulation.

[0149] The steps and methods involved in the above embodiment two correspond to those in embodiment one. For specific implementation details, please refer to the relevant description section of embodiment one.

[0150] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0151] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in or transmitted through a computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that a computer can access or a data processing device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, an optical medium, or a semiconductor medium, etc.

[0152] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for quantitatively evaluating the mechanical behavior of materials under the action of an external medium, characterized in that, Includes the following steps: Prepare a sample of the metallic material to be tested and perform surface treatment on the sample; In-situ monitoring and loading tests are performed on the samples under the action of external media to collect information on the deformation response and damage events of the metal material samples under test. A basic quantitative relationship is established based on the deformation response and damage event information, and surface stress inversion is performed to obtain the equivalent surface force result. Based on the coupling relationship of multiple external media, the evaluation index of the mechanical behavior induced by the external media is calculated according to the equivalent surface force, and the quantitative evaluation result of the metal material sample under test under the action of the external media is obtained.

2. The quantitative evaluation method for the mechanical behavior of materials under the action of an external medium as described in claim 1, characterized in that, Surface treatment of the metal material sample to be tested involves sensitizing at least one surface of the metal material sample to the medium, which easily forms a surface state that can respond to the external medium.

3. The quantitative evaluation method for the mechanical behavior of materials under the action of an external medium as described in claim 2, characterized in that, The specific steps of the medium sensitization process include: constructing a molecular adsorption layer on the surface of the metal sample to be tested by self-assembling a molecular layer, surfactant, organic or inorganic thin film; preparing a porous metal sample by selective corrosion by electrochemical means, and placing the porous metal sample in an electrolyte-wetting state.

4. The quantitative evaluation method for the mechanical behavior of materials under the action of an external medium as described in claim 1, characterized in that, The external medium includes at least one of the following: mechanochemical medium or electrochemical medium. The mechanochemical medium is used to induce the formation and stabilization of the molecular adsorption layer, and a chain length variable group is constructed by changing the organic molecular chain length parameter. Different organic molecular chain lengths correspond to different mechanical response differences. The electrochemical medium is the electric field and chemical electric field environment for generating porous metal samples and testing material properties.

5. The method for quantitatively evaluating the mechanical behavior of materials under the action of an external medium as described in claim 1, characterized in that, In-situ monitoring and loading tests of samples under the influence of external media include in-situ monitoring under the influence of mechanical and chemical media, as well as loading tests under the influence of electrochemical media.

6. The quantitative evaluation method for the mechanical behavior of materials under the action of an external medium as described in claim 5, characterized in that, The specific steps for in-situ monitoring under the influence of mechanical and chemical media include: The deflection and shape changes of the free end of the cantilever are measured using an optical microscope, laser displacement sensor, interferometer, or capacitive displacement sensor. Local strain fields are measured using strain gauges, fiber optic gratings, or digital imaging. Microcrack initiation and propagation events can be monitored using acoustic emission sensors or high-frequency force sensors. The variation characteristics of the deformation removal mode of the material under mechanical bias loading were observed using a high-speed camera and in-situ digital images.

7. The quantitative evaluation method for the mechanical behavior of materials under the action of an external medium as described in claim 5, characterized in that, The specific steps for performing loading tests under the action of an electrochemical medium include: In-situ characterization setup under the influence of electrochemical media; In-situ compression loading of nanoporous samples under the action of electrochemical media.

8. The quantitative evaluation method for the mechanical behavior of materials under the action of an external medium as described in claim 1, characterized in that, The results of equivalent surface force include the time-varying results of equivalent surface stress and the time-varying results of equivalent surface driving force. The equivalent surface stress is calculated from the deflection signal, and the time-varying results of equivalent surface driving force are used to characterize the driving force of surface stress on deformation or damage, including two types of driving force: load-type driving force and strength-type driving force.

9. The method for quantitatively evaluating the mechanical behavior of materials under the action of an external medium as described in claim 1, characterized in that, Based on the coupling relationship of multiple external media, the specific steps for calculating the evaluation index of the mechanical behavior induced by the external media according to the equivalent surface force are as follows: Set general metrics; The chain length effect of the interaction pathway between mechanical and chemical media is evaluated based on the set general indicators. The mechanical properties of the electrochemical field medium are controlled and evaluated based on the established general indicators.

10. A quantitative evaluation device for a method of quantitatively evaluating the mechanical behavior of materials under the action of an external medium as described in any one of claims 1-9, comprising a mechanochemical effect testing device and an electrochemical effect testing device.

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