Optical microscope-based material indentation mechanical property testing device and method

Abstract

The application discloses a kind of material indentation mechanical property testing device and method based on optical microscopy, it is related to material microscopic mechanical property testing technical field, the material indentation mechanical property testing device based on optical microscopy includes optical microscope, transparent indenter, sample table, force sensor, observation baffle, displacement sensor, load loading component and controller, in the indentation test process of material sample using transparent indenter, indentation image, indentation depth and indentation load under the contact state of transparent indenter and material are respectively collected in real time by optical microscope, displacement sensor and force sensor, and based on this, the mechanical property of material micro area in the indentation process of material sample can be characterized in real time, provide new technical means for material microscopic mechanical property testing technical field.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-mechanical property testing of materials, in particular to a material indentation mechanical property testing device and method based on optical microscopy. BACKGROUND

[0002] Indentation testing technology is a common material testing method based on elastic contact model. The performance and quality of the material are characterized by applying a certain load and observing the deformation of the material under the load. As a non-destructive testing method, indentation testing technology does not affect the integrity of the material during testing, and can test rare materials. Indentation testing technology has the characteristics of high flexibility, wide application range, low cost, etc. These application characteristics make indentation testing technology more feasible and valuable than other testing methods. It is an indispensable testing means in the fields of material science and engineering manufacturing. Therefore, the development of material testing technology can provide technical support for micro-material performance evaluation, quality control, new material research and development, intelligent manufacturing and other fields.

[0003] Generally, indentation testing applies a certain amount of static or dynamic force on the surface of the material to cause the material to deform and form an indentation. The contact area is indirectly calculated by using the indentation depth to characterize the mechanical properties of the material. The currently commonly used testing method is the Oliver-Pharr method. As the most classic testing method, the Oliver-Pharr method has been widely used in the field of materials and is an international standard test method. However, the Oliver-Pharr method can only calculate the material parameters at the maximum load, and it cannot continuously obtain the micro-region mechanical parameters of the material during a single indentation process. SUMMARY

[0004] The purpose of the present application is to provide a material indentation mechanical property testing device and method based on optical microscopy, which can characterize the elastic-plastic mechanical behavior of the micro-region of the material sample during the indentation process in real time.

[0005] To achieve the above purpose, the present application provides the following solutions:

[0006] In a first aspect, the present application provides a material indentation mechanical property testing device based on optical microscopy, comprising:

[0007] a material indentation mechanical property testing sub-device and a controller;

[0008] The material indentation mechanical property testing sub-device comprises an optical microscope, a transparent indenter, a sample stage, a force sensor, an observation baffle, a displacement sensor and a load loading assembly arranged in the same direction in sequence.

[0009] The transparent indenter is fixed below the optical microscope by a clamp.

[0010] The sample table is used to hold a material sample, and when the sample table holds the material sample, the material sample is located directly below the transparent indenter;

[0011] The force sensor is located between the sample table and the observation baffle;

[0012] The displacement sensor and the load loading assembly are both located below the observation baffle;

[0013] The load loading assembly is used to apply a load force to the sample table, and the load force is the force of the material sample moving towards the transparent indenter;

[0014] The optical microscope is used to collect the indentation image of each indentation in the indentation test process of the material sample in real time;

[0015] The force sensor is used to collect the indentation depth of each indentation in real time, wherein the indentation depth is the displacement of the observation baffle;

[0016] The displacement sensor is used to collect the indentation load of each indentation in real time;

[0017] The optical microscope, the force sensor, the displacement sensor, and the load loading assembly are all connected to the controller;

[0018] The controller is used to control the load loading assembly and calculate the material mechanical property parameters according to the corresponding indentation image, indentation depth, and indentation load.

[0019] In a second aspect, the present application provides a material indentation mechanical property testing method based on optical microscopy, which is implemented by the material indentation mechanical property testing device based on optical microscopy, and includes:

[0020] Controlling the load loading assembly to apply a load force to the sample table;

[0021] Obtaining the indentation image, indentation depth, and indentation load of each indentation in the indentation test process of the material sample;

[0022] Calculating the material mechanical property parameters according to the corresponding indentation image, indentation depth, and indentation load.

[0023] Optionally, calculating the material mechanical property parameters according to the corresponding indentation image, indentation depth, and indentation load specifically includes:

[0024] gray processing is performed on the indentation image to obtain a gray indentation image;

[0025] an indentation contour is determined according to a pixel gray value in the gray indentation image and a gray threshold value;

[0026] edge extension is performed on the indentation contour to obtain an extended indentation region;

[0027] edge burrs of the extended indentation region are removed and smoothing processing is performed to obtain a processed indentation image;

[0028] a contact area is determined according to the processed indentation image;

[0029] it is judged whether the contact area exists false detection, to obtain a first judgment result;

[0030] if the first judgment result is yes, holes and cracks in the processed indentation image are filled to obtain a filled processed indentation image;

[0031] the filled processed indentation image is taken as a new processed indentation image, and the step of determining the contact area according to the processed indentation image is returned to;

[0032] if the first judgment result is no, a contact depth is calculated according to the contact area;

[0033] an elastic deformation depth is calculated according to the contact depth and a corresponding indentation depth;

[0034] a material mechanical property parameter is calculated according to the indentation depth, the indentation load, the contact area, the contact depth and the elastic deformation depth.

[0035] Optionally, the material mechanical property parameter includes stiffness, hardness and equivalent modulus of the material; and the specific calculation process of the stiffness includes:

[0036] the stiffness is calculated according to the indentation load and the elastic deformation depth corresponding to each indentation.

[0037] Optionally, the specific calculation process of the hardness includes:

[0038] the hardness under different indentation depths is calculated according to the indentation load and the contact area corresponding to each indentation, wherein the contact area and the indentation depth have a one-to-one correspondence.

[0039] Optionally, the specific calculation process of the equivalent modulus includes:

[0040] the equivalent modulus is calculated according to the indentation load, the elastic deformation depth and the contact area corresponding to each indentation.

[0041] Optionally, after the step of "calculating material mechanical property parameters according to the corresponding indentation image, the indentation depth and the indentation load", the optical microscopy-based material indentation mechanical property test method further comprises:

[0042] According to the corresponding contact depth, the indentation depth and the elastic deformation depth, it is judged whether the material sample has a bulging phenomenon, and a second judgment result is obtained.

[0043] When the second judgment result is yes, a plastic bulging parameter of the material sample under the bulging phenomenon is calculated according to the contact depth, the indentation depth, the elastic deformation depth and the indentation load.

[0044] Optionally, the calculation formula of the stiffness is:

[0045] S = P / h s ;

[0046] Wherein, S represents the stiffness; P represents the indentation load; h s represents the elastic deformation depth.

[0047] Optionally, the calculation formula of the hardness is:

[0048] H = P / A c ;

[0049] Wherein, H represents the hardness; P represents the indentation load; A c represents the contact area.

[0050] Optionally, the calculation formula of the reduced modulus is:

[0051]

[0052] Wherein, E r represents the reduced modulus; S represents the stiffness; β represents a constant; A c represents the contact area.

[0053] According to the specific embodiments provided in the present application, the following technical effects are disclosed:

[0054] The present application provides a material indentation mechanical property testing device and method based on optical microscopy. The material indentation mechanical property testing device includes an optical microscope, a transparent indenter, a sample table, a force sensor, an observation baffle, a displacement sensor, a load loading assembly and a controller. During the indentation test on the material sample using the transparent indenter, the indentation image, the indentation depth and the indentation load in the contact state between the transparent indenter and the material are respectively collected in real time by the optical microscope, the displacement sensor and the force sensor. Based on this, the mechanical properties of the material micro-area of ​​the material sample during the indentation process can be characterized in real time, providing a new technical means for the field of material micro-mechanical property testing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0056] Figure 1 A schematic diagram of the structure of a material indentation mechanical properties testing device based on optical microscopy provided in an embodiment of the present application;

[0057] Figure 2 A schematic diagram of the process of the material indentation mechanical property testing method based on optical microscopy provided in an embodiment of the present application;

[0058] Figure 3 Schematic diagram of the relationship between the indentation load and the contact depth during the indentation process in an embodiment of the present application;

[0059] Figure 4 Schematic diagram of the actual contact area of ​​the indenter at different indentation depths under an optical microscope in an embodiment of the present application;

[0060] Figure 5 Schematic diagram of the corresponding relationship between the actual contact area and the contact depth during the indentation process in the embodiment of the present application

[0061] Figure 6 Schematic diagram of the relationship between the indentation load and the elastic deformation depth during the indentation process in an embodiment of the present application;

[0062] Figure 7 This is a schematic diagram of the relationship between the indentation load and the actual contact area in the embodiment of the present application;

[0063] Figure 8 Schematic diagram of the indentation cross section during the indentation process in an embodiment of the present application.

[0064] Reference numerals:

[0065] 1-Optical microscope; 2-Transparent indenter; 3-Material sample; 4-Force sensor; 5-Displacement sensor; 6-Fixture; 7-Sample stage; 8-Observation baffle; 9-Piezoelectric stack; 10-Flexible hinge. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0067] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0068] like Figure 1 As shown, an embodiment of the present application provides a material mechanical parameter indentation testing device based on high-resolution optical microscopy, comprising:

[0069] Material indentation mechanical properties testing sub-device and controller.

[0070] The material indentation mechanical property testing sub-device comprises an optical microscope (1), a transparent indenter (2), a sample table (7), a force sensor (4), an observation baffle (8), a displacement sensor (5), and a load loading assembly, which are sequentially arranged in the same direction. The optical microscope (1) of this embodiment is a high-resolution optical microscope, and the load loading assembly comprises a piezoelectric stack (9) and a flexible hinge (10). The piezoelectric stack (9) is connected to the flexible hinge (10), and the flexible hinge (10) is connected to the observation baffle (8).

[0071] The transparent indenter (2) is fixed directly below the optical microscope (1) via a clamp (6).

[0072] The sample table (7) is used to hold a material sample (3). When the sample table (7) holds the material sample (3), the material sample (3) is located directly below the transparent indenter (2), and the polished surface of the material sample (3) faces the transparent indenter (2) and the optical microscope (1).

[0073] The force sensor (4) is located between the sample platform (7) and the observation baffle (8).

[0074] The displacement sensor (5) and the load loading assembly are both located below the observation baffle (8).

[0075] The load loading assembly is used to apply a loading force to the sample table (7), and the loading force is a force for moving the material sample (3) towards the transparent indenter (2).

[0076] The optical microscope (1) is used to collect the indentation image of the material sample (3) in real time during each indentation in the indentation test.

[0077] The force sensor (4) is used to collect the indentation depth in real time, wherein the indentation depth is the displacement of the observation baffle (8).

[0078] The displacement sensor (5) is used to collect the indentation load in real time, and the displacement sensor (5) in the embodiment is a capacitive displacement sensor.

[0079] The optical microscope (1), the force sensor (4), the displacement sensor (5) and the piezoelectric stack (9) in the load loading assembly are connected with the controller.

[0080] The controller is used to control the piezoelectric stack to enable the piezoelectric stack (9) to drive the flexible hinge (10) to move the sample table (7) and calculate the material mechanical property parameters according to the obtained indentation image, indentation depth and indentation load.

[0081] The material indentation mechanical property testing device provided in the embodiment drives the flexible hinge (10) to move the sample table (7) through the piezoelectric stack (9), so that the material sample (3) is fed towards the transparent indenter (2), and at the same time, the optical microscope (1) is used to observe the indentation process in real time through the transparent indenter (2) to obtain the indentation image information (i.e. indentation image) corresponding to any indentation depth. i and the indentation load P i Based on the image information, the contact area A ci under any indentation load can be obtained by processing the indentation image. ci According to the indentation depth, indentation load, contact area and / or contact depth, the material mechanical property parameters of the material sample (3) under different indentation loads can be obtained in real time.

[0082] The device provided in the embodiment can also calculate the plastic bulging parameters of the material sample (3) when the bulging phenomenon occurs by using the indentation image, indentation depth and indentation load.

[0083] Another embodiment of the present application provides an optical microscopy-based material indentation mechanical property testing method, which comprises Figure 1 The optical microscopy-based material indentation mechanical property testing device is implemented, and the optical microscopy-based material indentation mechanical property testing method comprises the following steps:

[0084] Controlling the load loading assembly to exert a loading force on the sample table.

[0085] Obtaining an indentation image, an indentation depth and an indentation load of each indentation of the material sample in the indentation test process.

[0086] Calculating a material mechanical property parameter according to the corresponding indentation image, indentation depth and indentation load.

[0087] In order to make the person skilled in the art more clearly understand the use process of the above device and the specific execution process of the above method, the following Figures 2-8 is explained.

[0088] Referring to Figure 2 , the material indentation mechanical property testing method comprises the following steps:

[0089] Step one, selecting a rectangular material sample (3), and cleaning the side surface to be pressed of the material sample (3) with alcohol and water, and grinding and polishing the side surface to be pressed of the material sample (3) by using a polishing disc, so that the surface is smooth and flat to reduce measurement error.

[0090] Step two, fixing the transparent indenter (2) below the high-resolution optical microscope (1) by using the clamp (6), and fixing the material sample (3) in the sample table (7).

[0091] Step three, the material sample (3) is located below the transparent indenter (2), the sample table (7) is parallel to the horizontal plane, and the indentation position of the material sample (3) can be directly observed by the high-resolution optical microscope (1). Adjust the focal length of the high-resolution optical microscope (1) so that the tip of the transparent indenter (2) can be directly observed by the high-resolution optical microscope (1).

[0092] Step four, energizing the piezoelectric stack (9), and controlling the piezoelectric stack (9) by the controller to drive the flexible hinge (10) to exert a load on the observation baffle (8), until the material sample (3) and the surface of the transparent indenter (2) are in contact with each other, and the loading direction is the direction in which the sample table (7) moves towards the transparent indenter (2).

[0093] Step five, as Figure 3As shown, indentation test is performed on sample (3), before the test, the capacitive displacement sensor (5) and the force sensor (4) are zeroed, the high-resolution optical microscope (1) is used to obtain the image of the contact area through the transparent indenter (2), and the indentation image is obtained, and the actual indentation depth h i (i.e. indentation depth) obtained by the displacement sensor (5) at the i-th indentation image acquisition time (i-th feeding) in the indentation process is recorded i , and the indentation load P ci obtained by the force sensor (4) is recorded.

[0094] Step six, weighted average is performed on each pixel in the indentation image obtained in step five, the conversion from color image to gray image is realized, and the gray indentation image is obtained. A gray value threshold is selected, the approximate outline of the indentation is determined by comparing the gray value of the pixel in the gray indentation image with the threshold, the edge expansion (expansion from the edge) is performed on the indentation outline to fill the indentation cavity and connect the incomplete area to form a complete area, and the expanded indentation area is obtained, as shown in Figure 4 The actual contact area A c (i.e. contact area) is obtained by calibrating the processed indentation image, and it is judged whether the actual contact area is misdetected, if so, the holes and cracks in the image are filled and the identification process is performed again on the basis of the overall structure of the original shape.

[0095] Step seven, as shown in Figure 5 , the actual contact area A c is converted into the contact depth h ci using the area function of the transparent indenter used. The contact depth h c (i.e. the contact depth corresponding to the i-th feeding) at any stop indentation time is obtained by the area function of the indenter and the actual contact area obtained in step six, and the relationship between the contact depth and the indentation load is shown in Figure 3 .

[0096] Step eight, as shown in Figure 6 , the relationship between the indentation depths at different stages is known: h s = h-h i , the indentation depth h ci obtained in step five and the contact depth h si obtained in step seven are used to simultaneously obtain h s at any time period, so that the corresponding load and elastic deformation depth relationship is represented by the formula S=P / h n or S n =P sn, the obtained elastic deformation depth-load relationship can be used to represent the indentation stiffness (i.e. stiffness) in real time.

[0097] Step nine, as shown in the figure, the actual contact area A ci obtained in step seven is mapped to the contact depth h ci obtained in step eight, and the indentation hardness (i.e. material hardness) at any indentation depth can be represented simultaneously by the formula H = P / A c or H n = P n / A cn . In addition, based on the contact stiffness S obtained in step eight and the actual contact area A c obtained in step six, the material reduced modulus E or can be represented continuously by the formula E = (1-β)S / h

[0098] where β is a constant related to the geometry of the indenter, for a Berkovich indenter, β = 1.034; for a Vickers indenter, β = 1.012.

[0099] Step ten, using h c obtained in step five, h s obtained in step seven, and h c obtained in step eight, it is determined whether the material sample (3) has undergone bulging, and when h s ≠ h s , the material sample (3) has undergone bulging. When bulging occurs, the plastic bulging parameter at each indentation depth can be represented by h c +h -h = f(σ / E), where σ is the yield strength of the material and E is the elastic modulus of the material.

[0100] The material indentation mechanical property testing device and method provided by the embodiment solve the problems that the existing micro-nano indentation quasi-static testing method cannot continuously obtain the micro-region mechanical parameters of the material in a single indentation process, the existing micro-nano indentation testing method cannot directly obtain the elastic deformation depth, and the test error caused by the material bulging phenomenon. The embodiment can realize real-time characterization of multiple mechanical properties of the material under any load in the loading process by synchronously and real-time recording of the actual contact area between the transparent indenter and the material sample and the indentation depth of the transparent indenter based on the displacement sensor and the high-resolution optical microscope during the indentation process. The elastic-plastic mechanical parameters of the material micro-region under each load can be continuously obtained in a single indentation process, and the bulging phenomenon can be quantitatively characterized. This will enable the indentation testing technology to directly characterize the elastic-plastic mechanical behavior of the material micro-region, further expand the precision and application range of the indentation testing technology, and provide a new technical means for the material micro-mechanical property testing technology field. Compared with the existing testing technology, the embodiment has the advantages of rich test information and more accurate test results, and is widely applicable to the test materials.

[0101] By using the transparent indenter to perform indentation testing on the sample, the contact state of the transparent indenter and the material is observed in real time by the optical microscope, and the actual indentation depth and the actual contact area are synchronously obtained, the elastic-plastic mechanical behavior of the material micro-region in the indentation process can be characterized in real time. Compared with the existing testing technology, the contact area synchronously obtained by the indentation testing of the embodiment can obtain the material stiffness under any load in the loading process. The embodiment has the advantages of simple operation steps and strong universality, and has wide application prospects in the field of material micro-mechanical property testing technology.

[0102] The principles and implementation modes of the present application are described by applying specific examples in this paper, and the above embodiment descriptions are only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range will be changed. In conclusion, the content of the specification should not be understood as a limitation of the present application.

Claims

1. An optical microscopy-based material indentation mechanical property testing device, characterized in that, The material indentation mechanical property testing device based on optical microscopy comprises: a material indentation mechanical property testing sub-device and a controller; the material indentation mechanical property testing sub-device comprises, in sequence in the same direction, an optical microscope, a transparent indenter, a sample stage, a force sensor, an observation baffle, a displacement sensor, and a load loading assembly; the transparent indenter is fixed below the optical microscope by a clamp; the sample stage is used for containing a material sample, and when the sample stage contains the material sample, the material sample is located directly below the transparent indenter; the force sensor is located between the sample stage and the observation baffle; the displacement sensor and the load loading assembly are both located below the observation baffle; the load loading assembly is used for applying a loading force to the sample stage; the loading force is the force of the material sample moving towards the transparent indenter; the optical microscope is used for collecting indentation images of the material sample at each time of indentation in real time during the indentation test; the displacement sensor is used for collecting the indentation depth at each time of indentation in real time, wherein the indentation depth is the displacement of the observation baffle; the force sensor is used for collecting the indentation load at each time of indentation in real time; the optical microscope, the force sensor, the displacement sensor, and the load loading assembly are all connected to the controller; the controller is used for controlling the load loading assembly and calculating material mechanical property parameters according to the corresponding indentation images, indentation depths, and indentation loads; specifically: the indentation images are processed to obtain the contact area under any indentation load, the contact area is processed in combination with the area function of the indenter to obtain the contact depth under any indentation load, and the material mechanical property parameters of the material sample under different indentation loads are obtained in real time according to the indentation depth, indentation load, contact area, and contact depth through calculation; each pixel in the indentation image is subjected to weighted average to obtain a gray-scale indentation image; the indentation contour is determined according to the gray value of the pixel in the gray-scale indentation image and a gray threshold; the edge of the indentation contour is expanded to obtain an expanded indentation area; the edge burrs of the expanded indentation area are removed and the boundary is smoothed to obtain a processed indentation image; the actual contact area is determined according to the processed indentation image, and it is determined whether the actual contact area is misdetected; if yes, the holes and cracks in the processed indentation image are filled to obtain a filled processed indentation image, the filled processed indentation image is taken as a new processed indentation image, and the step of "determining the actual contact area according to the processed indentation image" is returned; if no, the contact depth is calculated according to the actual contact area; whether the material sample has the bulging phenomenon is determined according to the corresponding contact depth, indentation depth, and elastic deformation depth; when the bulging phenomenon occurs, the plastic bulging parameters of the material sample under the bulging phenomenon are calculated according to the contact depth, indentation depth, elastic deformation depth, and indentation load.

2. A method for testing the mechanical properties of a material under indentation based on optical microscopy, characterized in that, The optical microscopy-based material indentation mechanical property testing method is implemented by the optical microscopy-based material indentation mechanical property testing device of claim 1, and the optical microscopy-based material indentation mechanical property testing method comprises the following steps: controlling the load loading assembly to apply a loading force to the sample table; obtaining an indentation image, an indentation depth and an indentation load of each indentation in the indentation test process of the material sample; calculating a material mechanical property parameter according to the corresponding indentation image, indentation depth and indentation load.

3. The optical microscopy-based material indentation mechanical property testing method according to claim 2, wherein, The specific calculation process of the material mechanical property parameter according to the corresponding indentation image, indentation depth and indentation load comprises the following steps: performing gray scale processing on the indentation image to obtain a gray scale indentation image; determining an indentation contour according to a pixel gray scale value and a gray scale threshold value in the gray scale indentation image; performing edge extension on the indentation contour to obtain an extended indentation area; removing edge burrs of the extended indentation area and performing smoothing processing to obtain a processed indentation image; determining a contact area according to the processed indentation image; judging whether the contact area is misdetected to obtain a first judgment result; if the first judgment result is yes, filling holes and cracks in the processed indentation image to obtain a filled processed indentation image; taking the filled processed indentation image as a new processed indentation image and returning to the step of determining a contact area according to the processed indentation image; if the first judgment result is no, calculating a contact depth according to the contact area; calculating an elastic deformation depth according to the contact depth and the corresponding indentation depth; calculating a material mechanical property parameter according to the indentation depth, indentation load, contact area, contact depth and elastic deformation depth.

4. The optical microscopy-based material indentation mechanical property testing method according to claim 3, wherein, The material mechanical property parameter comprises stiffness, hardness and equivalent modulus of the material; the specific calculation process of the stiffness comprises the following steps: calculating the stiffness according to the indentation load and the elastic deformation depth corresponding to each indentation.

5. The optical microscopy-based material indentation mechanical property testing method according to claim 4, wherein, The specific calculation process of the hardness comprises the following steps: calculating the hardness at different indentation depths according to the indentation load and the contact area corresponding to each indentation, wherein the contact area and the indentation depth have a one-to-one correspondence.

6. The optical microscopy-based material indentation mechanical property testing method of claim 4, wherein, The specific calculation process of the equivalent modulus comprises the following steps: calculating the equivalent modulus according to the indentation load, contact area and elastic deformation depth corresponding to each indentation.

7. The material indentation mechanics performance test method according to claim 3, characterized in that, After the step of calculating a material mechanical property parameter according to the corresponding indentation image, indentation depth and indentation load is performed, the optical microscopy-based material indentation mechanical property testing method further comprises the following steps: judging whether the material sample has a bulging phenomenon according to the contact depth, indentation depth and elastic deformation depth corresponding to each indentation to obtain a second judgment result; when the second judgment result is yes, calculating a plastic bulging parameter of the material sample under the bulging phenomenon according to the contact depth, indentation depth, elastic deformation depth and indentation load.

8. The optical microscopy-based material indentation mechanical property testing method of claim 4, wherein, The calculation formula of the stiffness is: ； wherein, represents the rigidity; represents the indentation load; represents the elastic deformation depth.

9. The optical microscopy-based material indentation mechanical property testing method of claim 4, wherein, The calculation formula of the hardness is: ； wherein, represents a hardness; represents an indentation load; represents a contact area.

10. The optical microscopy-based material indentation mechanical property testing method of claim 4, wherein, The calculation formula of the equivalent modulus is: ； wherein, represents the reduced modulus; represents the stiffness; represents the constant; represents the contact area.

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