In-situ testing method and system for high temperature performance of a material

Abstract

The application provides an in-situ testing method and system for high-temperature performance of a material, which comprises the following steps: in a high-temperature environment, the side of a pressure head for pressing a testing sample during loading and the side of the pressure head on the testing sample after unloading are respectively subjected to in-situ microprojection, so as to obtain the indentation width d and the residual indentation width d c Therefore, high-precision measurement of high-temperature sensitive indentation displacement is realized. Furthermore, in combination with a derived formula, the hardness, elastic recovery rate and energy dissipation rate of the material in the high-temperature environment are obtained, the testing and evaluation of the high-temperature performance of the material which cannot be realized at home and abroad in the past are completed, and the application has the characteristics of simplicity, innovation, convenience and high efficiency.

Description

Technical Field

[0001] This invention relates to the field of materials performance testing technology, and in particular to an in-situ testing method and system for high-temperature properties of materials. Background Technology

[0002] The hardness, elastic recovery, and energy dissipation properties of engineering materials under high-temperature environments represent their reliability and safety in high-temperature applications. In particular, testing and evaluating the hardness, elastic recovery rate, and energy dissipation rate of high-temperature structural ceramics and composite materials under high-temperature oxidizing environments has always been a challenge. Obtaining the indentation depth and residual depth in indentation tests at high temperatures is extremely difficult. After cooling, the indentation cannot be found, and even if it is, thermal expansion and contraction will cause the indentation size at room temperature to be completely different from that at high temperatures, making it impossible to obtain the material's hardness, elastic recovery rate, and energy dissipation rate under high-temperature conditions.

[0003] Currently, there is a significant lack of instruments and equipment capable of testing the hardness, elastic recovery rate, and energy dissipation rate of materials under high-temperature oxidizing conditions. Furthermore, micro / nano indenters manufactured in the United States or Switzerland can only test these properties at room temperature, and cannot perform such tests at high temperatures. Summary of the Invention

[0004] The purpose of this application is to provide an in-situ testing method and system for the high-temperature properties of materials, enabling high-precision testing of the hardness, elastic recovery rate, and energy dissipation rate of engineering materials under high-temperature environments. The specific technical solution is as follows:

[0005] The first aspect of this application provides an in-situ testing method for the high-temperature properties of materials, which includes the following steps:

[0006] The test sample is placed in a high-temperature visualization furnace, and the pressure head is fixed vertically on the polished surface of the test sample.

[0007] Under the test environment, the indenter is uniformly loaded to a load F and held, so that the indenter is perpendicularly pressed into the polished surface to form an indentation; parallel light parallel to the polished surface is projected along the polished surface onto the side of the indenter pressed into the test sample using a first in-situ microscopic projection to obtain a first micrograph; the distance d' between the edge of the indenter projection in the first micrograph and the intersection point of the polished surface is measured; according to the indentation width d = d' / X1, where X1 is the first magnification of the first micrograph, the indentation width d is obtained;

[0008] Under the testing environment, the indenter is unloaded at a uniform speed. After unloading, the parallel light is projected along the polished surface onto the side of the indenter on the test sample using a second in-situ microscopic projection to obtain a second micrograph. The distance d between the edge of the indenter projection in the second micrograph and the intersection point with the polished surface is measured. c ', based on the residual indentation width d c =d c ' / X2, where X2 is the second magnification of the second photomicrograph, to obtain the residual indentation width d c ;

[0009] Based on the indentation width d and / or the residual indentation width d c The hardness and elastic recovery rate r of the test sample under the test environment were calculated. e and energy dissipation rate r d ;

[0010] The ambient temperature of the test environment is 300-1500℃.

[0011] In one embodiment of this application, the indenter is selected from Rockwell indenters, and during the test, the axial section containing the central axis of the Rockwell indenter is kept perpendicular to the parallel light; the hardness is Rockwell hardness HRC, which is obtained according to formula (1):

[0012] HRC=F / (πd 2 / sin60°) (1);

[0013] In formula (1), the unit of the indentation width d is mm, the unit of the load F is N, and the unit of the Rockwell hardness HRC is MPa.

[0014] In one embodiment of this application, the indenter is selected from Vickers indenters, and during the test, the plane formed by the two opposing edges of the Vickers indenter is kept perpendicular to the parallel light; the hardness is Vickers hardness HV, which is obtained according to formula (2):

[0015] HV = 0.204F / (d 2 / sin68°) (2);

[0016] In equation (2), the unit of the indentation width d is mm, the unit of the load F is N, and the unit of the Vickers hardness HV is MPa.

[0017] In one embodiment of this application, the elastic recovery rate r is obtained according to formula (3). e :

[0018] r e =(d–d c) / d (3);

[0019] In equation (3), the indentation width d and the residual indentation width d c The units for all values ​​are mm, and the elastic recovery rate r e The unit is %.

[0020] In one embodiment of this application, the energy dissipation rate r is obtained according to equation (4). d :

[0021] r d =d c / d (4);

[0022] In equation (4), the indentation width d and the residual indentation width d c The units are all mm, and the energy dissipation rate r d The unit is %.

[0023] In one embodiment of this application, the material of the pressure head is selected from hot-pressed silicon carbide.

[0024] In one embodiment of this application, the rates of uniform loading and uniform unloading can be the same or different, ranging from 0.1 to 1 mm / min, the loaded load F is 1 to 500 N, and the time for holding the load F is 5 to 30 seconds.

[0025] In one embodiment of this application, the first magnification X1, the second magnification X2, and the third magnification X3 may be the same or different, ranging from 50 to 1500.

[0026] The second aspect of this application provides a high-temperature in-situ testing system for implementing the testing method described in any embodiment of the first aspect of this application, comprising a visualization high-temperature furnace, a perforated fixture, an indenter, a universal testing machine, and a telephoto microscope.

[0027] The beneficial effects of this application are:

[0028] This application provides an in-situ testing method and system for the high-temperature properties of materials. The in-situ testing method involves performing in-situ microscopic projection on the side of the indenter pressed into the test sample during loading and on the side of the indenter on the test sample after unloading under high-temperature conditions. This yields a high-resolution first micrograph and a second micrograph, respectively carrying information on the indentation width and residual indentation width. Furthermore, the distances d' and d' between the edge of the indenter projection and the intersection point with the polished surface of the material, measured in the first and second micrographs respectively, are used to determine the indenter's properties. c ', thus obtaining the indentation width d and the residual indentation width d'. cThis enables high-precision measurement of the displacement of high-temperature sensitive indentations. Furthermore, the obtained indentation width and residual indentation width are combined with formulas (1)-(4) derived by the inventors based on the test method of this application to obtain the hardness, elastic recovery rate and energy dissipation rate of the material under high-temperature conditions, thereby achieving efficient testing of the high-temperature performance of the material.

[0029] The core of this invention is the innovative approach of using high-temperature in-situ photographic indentation to evaluate the hardness, elastic recovery rate, and energy dissipation rate of materials. This method includes the design of the silicon carbide indenter, the loading method, the evaluation and calculation of the indentation depth, and the indentation width d and residual indentation width d obtained through in-situ testing. c The method calculates the hardness, elastic recovery rate, and energy dissipation rate of materials. This application's testing method achieves the testing and evaluation of high-temperature hardness, high-temperature elastic recovery rate, and high-temperature energy dissipation rate of materials, which was previously impossible to achieve domestically or internationally, filling a gap in this field. Furthermore, it is simple, innovative, convenient, and efficient.

[0030] The high-temperature in-situ testing system provided in this application is used to implement the in-situ testing method for the high-temperature properties of the materials in this application. Therefore, the high-temperature in-situ testing system of this application can achieve efficient testing of the high-temperature hardness, high-temperature elastic recovery rate and high-temperature energy dissipation rate of the materials. In addition, the high-temperature in-situ testing system of this application has the characteristics of being simple, innovative and convenient.

[0031] Of course, implementing any method or system of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0032] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0033] Figure 1 This is a side cross-sectional schematic diagram of the contact position between the indenter and the test sample in steps S1-S3 of the test method of this application;

[0034] Figure 2 This is a schematic diagram of the first and second photomicrographs in steps S2-S3 of the test method of this application;

[0035] Figure 3 This is a simplified schematic diagram of the testing method in this application;

[0036] Figure 4 The first and second photomicrographs are shown in steps S2-S3 of Example 1.

[0037] Figure 5 The first and second photomicrographs are shown in steps S2-S3 of Example 4. Detailed Implementation

[0038] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in this application are within the scope of protection of this application.

[0039] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0040] The first aspect of this application provides an in-situ testing method for the high-temperature properties of materials, such as... Figure 1 As shown, it includes the following steps:

[0041] S1, after placing the test sample in the visualization high-temperature furnace, as follows: Figure 1 As shown in step S1, when the indenter 1 is fixedly and vertically placed on the polished surface 2 of the test sample, the central axis OO' of the indenter 1 is perpendicular to the polished surface 2. The polished surface 2 is a plane on the test sample with very small roughness and / or unevenness after polishing. Assuming that the weight of the indenter itself is not considered, at this time only the tip O of the indenter 1 contacts the polished surface 2.

[0042] S2, after heating the visualization high-temperature furnace to 300-1500℃, under this test environment, such as Figure 1 As shown in step S2, the indenter 1 is uniformly loaded with load F along the central axis O'O and held, so that the indenter 1 is pressed perpendicularly into the polished surface 2. The indenter 1 and the polished surface 2 come into contact with each other and are pressed to form an indentation 3. In order to measure the width of the indentation 3 at this time, parallel light parallel to the polished surface 2 is used to perform a first in-situ microscopic projection along the polished surface 2 onto the side of the indenter 1 pressed into the test sample at this time, and a first micrograph carrying information about the width d of the indentation is obtained (see Figure 2(a) Measure the distance d' between the intersection point of the edge of the projection of the indenter 1 and the projection of the polished surface 2 in the first photomicrograph, and divide d' by the first magnification X1 of the first photomicrograph to obtain... Figure 1 The indentation width d is shown in step S2. In this application, X1 is defined as D1' / D1, where D1' is the width of the first photomicrograph and D1 is the width of the actual field of view represented by the first photomicrograph. Based on the measured indentation width d, the depth of indentation 3, i.e., the indentation depth h, can be further obtained. m The area of ​​the indentation 3 formed by the indenter 1 contacting and pressing the polished surface 2 under the force of load F is referred to as the indentation contact area A;

[0043] S3, under the above test environment, such as Figure 1 As shown in step S3, after the indenter 1 is unloaded at a constant speed along the central axis OO', the indenter 1 is slowly lifted upwards along the central axis OO', leaving residual indentation 4 on the test sample. At this point, theoretically, only the tip apex O of the indenter 1 is in contact with the deepest part of the residual indentation 4 on the test sample. To measure this... Figure 1 The residual indentation width d shown in step S3 is... c A second in-situ microscopic projection was performed on the side of the indenter on the test sample to obtain the width d of the residual indentation. c The second photomicrograph of the information (see Figure 2 In (b) of the second photomicrograph, the distance d between the intersection point of the edge of the projection of the indenter 1 and the projection of the polished surface 2 is measured. c ', will d c Divide by the second magnification of the second photomicrograph by 2, and you get Figure 1 The residual indentation width d shown in step S3 is... c In this application, X2 is defined as D2' / D2, where D2' is the width of the second photomicrograph and D2 is the width of the actual field of view represented by the second photomicrograph. It should be noted that step S3 measures the width d of the residual indentation. c This is to further obtain the depth of the residual indentation 4, that is, the residual indentation depth h. f This is not for obtaining the area of ​​the residual indentation 4 after unloading. The result obtained in step S3 is as follows... Figure 1 The residual indentation width d shown in step S3 is... c It is not the width of the residual indentation 4, but the distance between the edge of the pressure head 1 and the intersection of the polished surface 2 after unloading.

[0044] S4, based on the indentation width d and / or the residual indentation width d c The hardness and elastic recovery rate r of the test sample under the test environment were calculated. e and energy dissipation rate rd ;

[0045] The inventors discovered that the testing method S1-S3 steps of this application achieve high-precision measurement of high-temperature sensitive indentation displacement. Furthermore, based on the indentation width d and the residual indentation width d... c The indentation depth h is obtained. m , residual indentation width d c The indentation contact area A is further combined with formulas (1)-(4) derived by the inventors based on the test method of this application to obtain the hardness, elastic recovery rate and energy dissipation rate of the material under high temperature environment, thereby realizing efficient testing of the high temperature performance of the material. The test method of this application has completed the testing and evaluation of high temperature hardness, high temperature elastic recovery rate and high temperature energy dissipation rate of materials that could not be achieved in the past at home and abroad, filling the gap in this field, and has the characteristics of simplicity, efficiency, innovation and convenience.

[0046] In this application, the central axis OO' of the indenter 1 in steps S1-S3 above is always perpendicular to the polishing surface 2. The first and second in-situ microscopic projections are both processes in which parallel light parallel to the polishing surface 2 is emitted by a light source behind the test sample. After the parallel light is projected onto the side of the test sample and the indenter along the polishing surface 2, it is received by the light receiver in front of the test sample and then magnified and imaged by a telephoto microscope to obtain the first and second microscopic images.

[0047] In this application, the lenses used for the first and second in-situ microscopic projections in steps S2-S3 above are telecentric lenses, in order to eliminate the measurement error caused by the phenomenon that the same test sample appears larger when closer and smaller when farther away in the same micrograph due to the inconsistent distance between the test sample and the lens.

[0048] In this application, in step S2 above, X1 is defined as D1' / D1, where D1' is the width of the first photomicrograph and D1 is the width of the actual field of view represented by the first photomicrograph. In step S3 above, X2 is defined as D2' / D2, where D2' is the width of the second photomicrograph and D2 is the width of the actual field of view represented by the second photomicrograph.

[0049] Preferably, under the same conditions, the first and second in-situ microscopic projections are performed, resulting in the first and second microscopic photographs having the same size and representing the same actual field of view. For example, the width of both the first and second microscopic photographs is 370 mm, and the width D of the actual field of view represented by both the first and second microscopic photographs is 2.49 mm, meaning the first and second magnifications are the same, i.e., X1 = X2.

[0050] In this application, during steps S2-S3 above, the first and second photomicrographs can be magnified and / or displayed using a display screen or monitor to facilitate the measurement of d' and d' in steps S2-S3 above. c The size of the display screen used in this application to enlarge and / or display the first and second photomicrographs is not particularly limited, as long as it can achieve the purpose of this application. For example, the first and second photomicrographs can be enlarged and displayed in the same way using the same 32-inch monitor (69.81cm × 39.27cm). d' is measured in the enlarged first photomicrograph, and then d' is divided by the first magnification factor X1 of the first photomicrograph to obtain the indentation width d. It should be noted that, at this time, the first magnification factor X1 of the first photomicrograph = D1' / D1, where D1' is the width of the first photomicrograph enlarged and displayed on the monitor when d' is measured, and D1 is the width of the actual field of view represented by the first photomicrograph.

[0051] Similarly, d is measured in the second photomicrograph magnified and displayed on the aforementioned monitor. c ', then d c Divide by the second magnification of the second photomicrograph by 2 to obtain the residual indentation width d. c At this point, the second magnification of the second photomicrograph is X2 = D2' / D2, where D2' is the measured value of d. c 'D2 is the width of the second photomicrograph displayed magnified on the monitor, where D2 is the width of the actual field of view represented by the second photomicrograph.

[0052] In one embodiment of this application, the indenter is selected from Rockwell indenters, such as... Figure 1 As shown, during the test, the axial section S containing the central axis OO' of the Rockwell indenter is maintained. OBC Perpendicular to the parallel light; wherein, OB and OC are two opposite sides of the conical Rockwell indenter; the hardness is the Rockwell hardness HRC, which is obtained according to formula (1):

[0053] HRC=4F / (πd 2 / sin60°) (1);

[0054] In formula (1), the unit of the indentation width d is mm, the unit of the load F is N, and the unit of the Rockwell hardness HRC is MPa.

[0055] In this application, assuming the weight of the indenter itself is not considered, and according to the Rockwell hardness definition, HRC = F / A, the hardness (unit: MPa) is equal to the applied load F (Newton force) divided by the indentation contact area A (unit: mm). 2When the indenter used is a conical Rockwell indenter with a cone angle of 120°, assuming no deformation of the indenter during the indentation process, then after the Rockwell indenter is pressed into the test sample under high temperature conditions, if... Figure 1 As shown in step S2, the indentation 3 formed by the contact and pressing of the indenter 1 and the polished surface 2 should, in three-dimensional space, conform to the Rockwell indenter pressing into the test sample, and be approximately conical. In this case, since the test process maintains the axial section S where the central axis OO' of the Rockwell indenter is located... OBC The distance d' between the edge of the indenter projection and the point where it intersects with the polished surface, measured from the first photomicrograph perpendicular to the parallel light, should be approximated as the projected length of the diameter of the bottom surface of the conical indentation, and the resulting indentation width d should also be approximated as the diameter of the bottom surface of the conical indentation.

[0056] As can be seen from the above, assuming the indenter does not deform during the pressing process, the contact area A of the Rockwell indenter's indentation under high temperature conditions is approximately equal to the lateral surface area of ​​a cone with an indentation width d as its diameter and a cone angle of 120°. The unit for the indentation width d is mm, and the unit for the indentation contact area A is mm. 2 Substituting the formula for the indentation contact area A into the definition formula for hardness HRC=F / A, we can obtain the formula (1) for calculating the Rockwell hardness HRC.

[0057] In this application, π is taken as 3.1416 and sin60° is taken as 0.866. Substituting these values ​​into the Rockwell hardness HRC formula (1), we can obtain:

[0058] HRC = 1.10262 F / d 2 (1-1);

[0059] In Equation (1-1), the unit of indentation width d is mm, the unit of load F is N, and the unit of Rockwell hardness HRC is MPa.

[0060] In this application, given the weight of the indenter itself, after the indenter is fixed vertically on the polished surface of the test sample, a tiny indentation, referred to as a weight indentation, will appear on the polished surface due to the weight of the indenter itself. Figure 1 As shown in step S1, in the above step S1, parallel light parallel to the polishing surface 2 can be used to perform initial in-situ microscopic projection along the polishing surface 2 onto the side of the contact position between the indenter 1 and the polishing surface 2 to obtain an initial photomicrograph, where X0 is the magnification of the initial photomicrograph; the distance d0' between the intersection point of the edge of the indenter projection and the polishing surface projection in the initial photomicrograph is measured, and d0' is divided by the magnification X0 of the initial photomicrograph to obtain the width d0 of the weight indentation; then the contact area of ​​the weight indentation of the Rockwell indenter is calculated. Then, subtract the self-weight indentation contact area A0 from the indentation contact area A under load F, and correct the Rockwell hardness HRC formula (1) as follows:

[0061]

[0062] In equation (1-2), the unit of indentation width d is mm, the unit of self-weight indentation width d0 is mm, the unit of load F is N, and the unit of Rockwell hardness HRC is MPa.

[0063] In one embodiment of this application, the indenter is selected from Vickers indenters, such as... Figure 1 As shown, the test process maintains the plane S formed by the two opposing edges OB and OC of the Vickers indenter. OBC Perpendicular to the parallel light; the hardness is Vickers hardness HV, which is obtained according to equation (2):

[0064] HV = 0.204F / (d 2 / sin68°) (2);

[0065] In equation (2), the unit of the indentation width d is mm, the unit of the load F is N, and the unit of the Vickers hardness HV is MPa.

[0066] In this application, the weight of the indenter itself is not considered. According to the Vickers hardness definition, HV = F / gA, and the hardness (unit: MPa) is equal to the applied load F (Newton force) divided by the gravitational acceleration g (unit: m). 2 After dividing by the indentation contact area A (in mm), the result is: / s 2 When the indenter used is a Vickers indenter with an included angle of 136° between its relative facets, forming a regular square pyramid, assuming no deformation of the indenter during the indentation process, then after the Vickers indenter is pressed into the test sample, as follows: Figure 1 As shown in step S2, the indentation 3 formed by the contact and pressing of the indenter 1 and the polished surface 2 should, in three-dimensional space, conform to the Vickers indenter pressing into the test sample, approximately forming a regular square pyramid shape. In this case, because the testing process maintains the two opposing edges OB and OC of the Vickers indenter forming the same plane S... OBC The distance d' between the edge of the indenter projection and the point where it intersects with the polished surface, measured from the second photomicrograph perpendicular to the parallel light, should be approximated as the projected length of the diagonal of the bottom face of the aforementioned pyramidal indentation, and the resulting indentation width d should also be approximated as the diagonal length of the bottom face of the pyramidal indentation.

[0067] As can be seen from the above, assuming no deformation of the indenter during the pressing process, the indentation contact area A of the Vickers indenter under high temperature conditions is approximately equal to the lateral surface area of ​​a regular square pyramid with the diagonal width d of the diagonal as the length of the base diagonal and an included angle of 136° between the opposite faces. The unit for the indentation width d is mm, and the unit for the indentation contact area A is mm. 2 Applying the formula for the indentation contact area A above, and taking the gravitational acceleration g as 9.8m... 2 / s, substituting into the definition formula of hardness HV=F / gA, we can obtain the formula (2) for calculating the Vickers hardness HV.

[0068] In this application, sin68° is taken as 0.9272. Substituting this into the formula (2) for Vickers hardness HV, we get:

[0069] HV = 0.189 F / d 2 (2-1);

[0070] In the formula, the unit of indentation width d is mm, the unit of load F is N, and the unit of Vickers hardness HV is MPa.

[0071] In this application, given the weight of the indenter itself, after the indenter is fixed vertically on the polished surface of the test sample, a tiny indentation, referred to as a weight indentation, will appear on the polished surface due to the weight of the indenter. In step S1 above, the distance d0' between the intersection point of the edge of the indenter projection and the projection of the polished surface in the first photomicrograph can be measured. Dividing d0' by the magnification X1 of the first photomicrograph yields the width d0 of the weight indentation; then, the contact area of ​​the Vickers indenter's weight indentation is calculated. Then, subtract the self-weight indentation contact area A0 from the indentation contact area A under load F, and correct the Vickers hardness HV formula (2) as follows:

[0072]

[0073] In one embodiment of this application, the elastic recovery rate r is obtained according to formula (3). e :

[0074] r e =(dd c ) / d (3);

[0075] In equation (3), the indentation width d and the residual indentation width d c The units for all values ​​are mm, and the elastic recovery rate r e The unit is %.

[0076] In one embodiment of this application, the energy dissipation rate r is obtained according to equation (4). d :

[0077] r d =d c / d (4);

[0078] In equation (4), the indentation width d and the residual indentation width d c The units are all mm, and the energy dissipation rate r d The unit is % , where: r d +r e =1.

[0079] In this application, assuming no deformation of the indenter during the pressing process, the pressing depth after loading is as follows for a Rockwell indenter with a cone apex angle of 120°, i.e., a half-apex angle of 60°. Similarly, residual indentation depth Substituting the formulas for indentation depth and residual indentation depth into the definition of elastic recovery rate: Elastic recovery rate r of the sample under Rockwell indenter test at high temperature e and energy dissipation rate r d The derivation process is as follows:

[0080] The elastic recovery rate is:

[0081] The energy dissipation rate is:

[0082] Similarly, for a Vickers indenter in the shape of a regular square pyramid with an included angle of 136° (i.e., a half-angle of 68°) between its opposite faces, the indentation depth after loading... Residual indentation depth The above-mentioned indentation depth h m and residual indentation depth h f Substituting the formula into the definition of elastic recovery rate: Elastic recovery rate r of the sample under Vickers indenter test at high temperature e and energy dissipation rate r d The derivation process is as follows:

[0083] The elastic recovery rate is:

[0084] The energy dissipation rate is:

[0085] It can be seen that for an indenter with a fixed tip angle, such as Figure 3 As shown, the indentation depth h m The residual indentation depth h is always proportional to the half-width d / 2 of the indentation. f With the residual indentation half-width d c The ratio 2 is always proportional, therefore, the energy dissipation rate can be calculated using the above formula for indenters with a fixed tip angle. Furthermore, without considering other forms of energy dissipation from the indentation, the elastic recovery rate r of the test sample... e and energy dissipation rate r dThe sum is one. The elastic recovery rate r of the sample tested under high temperature conditions. e and energy dissipation rate r d It can reflect the plastic deformation capacity of the test sample at different temperatures. In practice, it can be simply implemented by using the residual indentation width d after unloading. c Dividing the indentation width d by the force F, we obtain the energy dissipation rate r. d Then, subtract that value to obtain the elastic recovery rate r. e .

[0086] In one embodiment of this application, the indenter is made of silicon carbide. The inventors have discovered that indenters made of this material possess high strength and high-temperature resistance, making them suitable for the testing methods of this application.

[0087] In one embodiment of this application, the rates of uniform loading and uniform unloading can be the same or different, ranging from 0.1 to 1 mm / min, the loaded load F is 1 to 500 N, and the time for holding the load F is 5 to 30 seconds.

[0088] In one embodiment of this application, the first magnification X1 and the second magnification X2 are not particularly limited, as long as they achieve the purpose of this application. For example, the first magnification X1 and the second magnification X2 can be the same or different, ranging from 50 to 1500. Preferably, the first magnification X1 and the second magnification X2 are the same.

[0089] In this application, the resolution of the first and second micrographs can reach 1-2 μm or higher, thereby enabling the distances d' and / or d' between the edge of the indenter projection and the intersection point of the polished surface of the test sample, respectively measured in the first and / or second micrographs, to be calculated. c It has sufficient precision to achieve high-precision measurement of the hardness, elastic recovery rate and energy dissipation rate of test samples under high temperature environment.

[0090] In this application, there are no particular restrictions on how the first magnification X1 and the second magnification X2 are obtained. Under the same microscopic projection conditions, by dimensional calibration—that is, by determining the proportion of the image of an object of known size (such as a 1mm wide cylinder, a 1×1mm object, or a 1mm wide vernier caliper) occupying the entire width or height of the photomicrograph—the actual field of view represented by the width or height of the photomicrograph can be determined. The dimensions of other objects in the photomicrograph can then be calculated.

[0091] For example, under the same microscopic projection conditions, a photomicrograph is obtained by projecting a known-size object (such as a 1mm wide cylinder, a 1×1mm object, or a 1mm wide vernier caliper) onto a microscope. The distance L' between the projected edges of the known-size object in the obtained photomicrograph is measured and divided by the actual size L of the known-size object, i.e., X = L' / L, to obtain the magnification X of the photomicrograph obtained under this microscopic projection condition. Then, according to the definition: X = D' / D, where D' is the width of the photomicrograph (which can be measured on a monitor), the width D of the actual field of view represented by the photomicrograph can be deduced. Similarly, the height of the actual field of view represented by the photomicrograph can also be obtained.

[0092] The second aspect of this application provides a high-temperature in-situ testing system for implementing the testing method described in any embodiment of the first aspect of this application. The system includes a visualization high-temperature furnace, a perforated fixture, an indenter, a universal testing machine, and a telephoto microscope. The visualization high-temperature furnace provides a high-temperature testing environment platform; the perforated fixture supports the indenter under high-temperature conditions; the universal testing machine acts as a load loading and unloading system to load and unload the indenter; and the telephoto microscope performs in-situ microscopic projection of the test sample and the side of the indenter after loading and unloading, enabling high-precision measurement of the displacement of high-temperature sensitive indentations. This allows the high-temperature in-situ testing system of this application to efficiently test the high-temperature hardness, high-temperature elastic recovery rate, and high-temperature energy dissipation rate of material samples. Furthermore, the high-temperature in-situ testing system of this application is simple, innovative, and convenient.

[0093] Example

[0094] The following examples illustrate the implementation of this application in more detail.

[0095] Example 1

[0096] Test copper alloy samples at 900℃ and under a load of F = 100 Newtons (N) to measure Rockwell hardness, energy dissipation rate, and elastic recovery rate.

[0097] S1. Place the copper alloy sample in a visualization high-temperature furnace, and fix the Rockwell indenter (made of silicon carbide) with a fixture, placing it vertically on the polished surface of the copper alloy sample.

[0098] S2, the temperature of the visualization high-temperature furnace is raised to 900℃ and maintained. A Rockwell indenter is applied at a rate of 0.1 mm / min to a load F = 100 N and held for 15 seconds, causing the Rockwell indenter to be pressed vertically into the polished surface to form an indentation. Parallel light is used to perform the first in-situ microscopic projection along the polished surface onto the side of the Rockwell indenter pressed into the copper alloy sample, obtaining the first micrograph (see...). Figure 4a) In the first photomicrograph, the width D1' of the first photomicrograph is measured on the display screen and is 370mm. At this time, the distance d' between the edge of the Rockwell indenter projection and the intersection point of the polished surface in the first photomicrograph is 31mm.

[0099] In this case, the width of the true field of view represented by the first photomicrograph is D1 = 2.49 mm. According to the definition: the first magnification X1 = D1' / D1 = 370 / 2.49 = 148.6; then the indentation width d = d' / X1 = 31 / 148.6 = 0.208 mm.

[0100] S3, Under the test environment, the Rockwell indenter was unloaded at 0.1 mm / min, and after unloading, it remained for 15 seconds. Under the same microscopic projection conditions as the first in-situ microscopic projection described above, a second in-situ microscopic projection was performed on the side of the indenter on the copper alloy sample to obtain a second micrograph (see...). Figure 4 (b) Under the same magnified display conditions on the same screen, the width D2' of the second photomicrograph is measured to be 370 mm. The distance d between the edge of the Rockwell indenter projection and the intersection point of the polished surface in the second photomicrograph is then measured. c =29mm,

[0101] In this case, the width of the true field of view represented by the second photomicrograph is D2 = 2.49 mm. According to the definition: second magnification X2 = D2' / D2 = 370 / 2.49 = 148.6; therefore, the width of the residual indentation d c =d c ' / X2=29 / 148.6=0.195mm;

[0102] S4, based on the indentation width d and / or the residual indentation width d c The Rockwell hardness (HRC) and elastic recovery rate (r) of the copper alloy sample at 900℃ were calculated. e and energy dissipation rate r d ;

[0103] Rockwell hardness is: HRC = 4F / (πd) 2 / sin60°)=4×100 / (π0.208 2 (sin60°) = 2550 MPa = 2.55 GPa;

[0104] The energy dissipation rate is:

[0105] The elastic recovery rate is: r e =1-r d =1-0.937=0.063.

[0106] Examples 2 to 4

[0107] Except for the parameters shown in Table 1, the rest are the same as in Example 1.

[0108] The widths of the actual field of view represented by the first and second photomicrographs in Examples 2 to 4 are the same as in Example 1, D1 = D2 = 2.49 mm. Under the condition that the widths of the first and second photomicrographs on the display screen are both 370 mm, i.e., under the condition that the magnification X1 = X2 = 148.6, d' and d' are measured. c '.

[0109] In Example 4, the first photomicrograph taken at an ambient temperature of 25°C is shown below. Figure 5 As shown in a, the second photomicrograph is as follows: Figure 5 As shown in b in the figure.

[0110] Table 1

[0111]

[0112] The results of Examples 1-4 show that the Rockwell hardness of the copper alloy samples decreases with increasing ambient temperature, but the energy dissipation increases with increasing ambient temperature, indicating that the copper alloy samples exhibit greater plastic deformation at high temperatures, which is consistent with the deformation law of solid materials.

[0113] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. An in-situ testing method for the high-temperature properties of a material, comprising the following steps: The test sample is placed in a high-temperature visualization furnace, and the pressure head is fixed vertically on the polished surface of the test sample. Under test conditions, the indenter is uniformly loaded to a load F and held, so that the indenter is pressed vertically into the polished surface to form an indentation; Parallel light parallel to the polished surface is projected along the polished surface onto the side of the indenter pressed into the test sample using a first in-situ microscopic projection, resulting in a first micrograph. The distance between the edge of the indenter projection in the first micrograph and the intersection point with the polished surface is measured. d’ According to the width of the indentation d = d’ / X1, where X1 is the first magnification of the first photomicrograph, and the indentation width is obtained. d ; Under the testing environment, the indenter is unloaded at a uniform speed. After unloading, the parallel light is projected along the polished surface onto the side of the indenter on the test sample using a second in-situ microscopic projection to obtain a second micrograph. The distance between the edge of the indenter projection in the second micrograph and the intersection point with the polished surface is measured. d c ’ Based on the width of the residual indentation d c = d c ’ / X2, where X2 is the second magnification of the second photomicrograph, and the residual indentation width is obtained. d c ; According to the indentation width d The hardness of the test sample under the test environment is calculated; based on the indentation width... d and residual indentation width d c The elastic recovery rate of the test sample under the test environment was calculated. r e and energy dissipation rate r d ; The ambient temperature of the test environment is 300-1500℃.

2. The method according to claim 1, wherein, The indenter is selected from Rockwell indenters. During the test, the axial section containing the central axis of the Rockwell indenter is kept perpendicular to the parallel light; the hardness is Rockwell hardness. HRC The Rockwell hardness is obtained according to equation (1). HRC : ； In formula (1), the indentation width d The unit is mm, and the load F The unit is N, and the Rockwell hardness is... HRC The unit is MPa.

3. The method according to claim 1, wherein, The indenter is selected from Vickers indenters. During the test, the plane formed by the two opposing edges of the Vickers indenter is kept perpendicular to the parallel light; the hardness is Vickers hardness. HV The Vickers hardness is obtained according to equation (2). HV : ； In formula (2), the indentation width d The unit is mm, the unit of the load F is N, and the unit of the Vickers hardness is mm. HV The unit is MPa.

4. The method according to claim 1, wherein, The elastic recovery rate r is obtained according to equation (3). e : ； In formula (3), the indentation width d and the width of the residual indentation d c The units for all values ​​are mm, and the elastic recovery rate is... r e The unit is %.

5. The method according to claim 1, wherein, The energy dissipation rate r is obtained according to equation (4). d : ； In formula (4), the indentation width d and the width of the residual indentation d c The units for all values ​​are mm, and the energy dissipation rate is... r d The unit is %.

6. The method according to claim 1, wherein, The pressure head is made of hot-pressed silicon carbide.

7. The method according to claim 1, wherein, The rates of uniform loading and uniform unloading can be the same or different, ranging from 0.1 to 1 mm / min, and the loaded load... F The load is 1-500N, and the load F is held for 5-30 seconds.

8. The method according to claim 1, wherein, The first magnification factor X1 and the second magnification factor X2 can be the same or different, ranging from 50 to 1500.

9. A high-temperature in-situ testing system for implementing the testing method according to any one of claims 1-8, comprising a visualization high-temperature furnace, a perforated fixture, an indenter, a universal testing machine, and a telephoto microscope.

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