In-situ method for testing metal micro-area combustion characteristics

Abstract

The present application provides a method for in-situ testing of metal micro-area combustion characteristics, comprising the steps of: loading an in-situ heated sample rod containing a metal sample into a cabin of a transmission electron microscope, and adjusting the atmosphere in the cabin to a target atmosphere; heating the metal sample to a predetermined temperature by the in-situ heated sample rod; irradiating the metal sample with an electron beam generated by the transmission electron microscope; and obtaining the combustion characteristics of the metal sample at the moment of micro-area combustion. The present application induces micro-area combustion of a metal sample by heating the in-situ heated sample rod and irradiating the electron beam, obtains phase change information and interface migration information of the metal sample at the moment of micro-area combustion, and thereby realizes the analysis of the combustion behavior of the metal at the microscopic atomic scale.

Description

Technical Field

[0001] The present application relates to the technical field of metal combustion, and in particular to a method for in-situ testing of metal micro-region combustion characteristics. Background Art

[0002] Metal combustion refers to a new failure mode different from oxidation and melting that occurs under extreme conditions such as high temperature, high pressure, and high speed at a temperature far below the melting point of the metal. It is manifested in the phenomenon that the metal is instantly ignited and spreads rapidly. The essence of metal combustion is a violent chemical reaction caused by the accumulation of local energy of metal materials exceeding the critical value due to extreme conditions.

[0003] Metal combustion has the characteristics of instant ignition, rapid propagation, and multi-factor coupling. The droplet combustion method, laser ignition method, and promoted ignition method are currently commonly used to study the ignition mechanism of metals. However, the experimental data obtained based on the existing research methods can only roughly analyze the macroscopic combustion behavior of metals, and it is difficult to achieve in-situ testing and analysis of the metal combustion process at the microscopic scale. Summary of the invention

[0004] The purpose of this application is to provide a method for in-situ testing of metal micro-area combustion characteristics, so as to test the metal combustion process at a microscopic scale. The specific technical solution is as follows:

[0005] A method for in-situ testing of metal micro-area combustion characteristics, comprising the steps of:

[0006] The in-situ heated sample rod containing the metal sample is loaded into a chamber of a transmission electron microscope, and the atmosphere in the chamber is adjusted to a target atmosphere, wherein the target atmosphere is a vacuum atmosphere, a pure oxygen atmosphere, or a mixed gas atmosphere;

[0007] heating the metal sample to a predetermined temperature by in-situ heating the sample rod, wherein the predetermined temperature is lower than the melting point of the metal sample;

[0008] The metal sample was irradiated with an electron beam generated by a transmission electron microscope, and the electron beam density was controlled to 800 A cm 2 ~6000A·cm 2 , the electron beam irradiation area is 200nm 2 ~1500nm 2 , so that the metal sample undergoes micro-combustion;

[0009] The combustion characteristics of the metal sample at the moment of micro-area combustion are obtained, and the combustion characteristics include: phase change information and interface migration direction.

[0010] In one embodiment of the present application, the heating rate is 1° C. / s to 5° C. / s.

[0011] In one embodiment of the present application, the vacuum degree of the vacuum atmosphere is 2×10 -5 mbar~7×10 -6 mbar; the mixed gas atmosphere is a mixture of oxygen and nitrogen in a volume ratio of 1:0.2-4.

[0012] In one embodiment of the present application, the metal sample is selected from any one of titanium, titanium alloy, iron, iron alloy, magnesium, magnesium alloy, nickel, and nickel alloy.

[0013] In one embodiment of the present application, the metal sample is metal nanoparticles or metal nanosheets.

[0014] In one embodiment of the present application, irradiating a metal sample with an electron beam generated by a transmission electron microscope comprises:

[0015] The edge area of ​​the metal sample is irradiated by an electron beam generated by a transmission electron microscope.

[0016] In one embodiment of the present application, the method further includes the step of calculating the interfacial reaction atomic migration rate and interfacial reaction activation energy of the metal sample using the combustion characteristics.

[0017] In one embodiment of the present application, the following first expression is used to calculate the interface reaction atom migration rate:

[0018]

[0019] Where V represents the atomic migration rate of the interface reaction, L t is the vertical distance from the starting interface after the interface migration time t, L 0 is the interface migration time t 0 The vertical distance from the starting interface, t is the distance from the interface to L t The time elapsed, t 0 Migrate to L 0 The time elapsed.

[0020] In one embodiment of the present application, the following second expression is used to calculate the interfacial reaction activation energy:

[0021]

[0022] Among them, E a represents the activation energy of the interface reaction, V is the atomic migration rate of the interface reaction, T is the predetermined temperature, A is the pre-exponential factor, and R is the molar constant.

[0023] Beneficial effects of this application:

[0024] The method for in-situ testing of metal micro-area combustion characteristics provided in the present application induces micro-area combustion of metal samples through the combined action of in-situ heating of the sample rod and electron beam irradiation, obtains the phase change information and interface migration information of the metal sample at the moment of micro-area combustion, and then analyzes the combustion behavior of the metal at the microscopic atomic scale. The method for in-situ testing of metal micro-area combustion characteristics provided in the present application breaks through the shortcomings of existing macroscopic testing methods that cannot obtain material combustion characteristics from the microscopic atomic scale, and existing simple microstructural analysis methods based on transmission electron microscopy, scanning electron microscopy, etc. that cannot induce metal combustion. Of course, the implementation of any product or method of the present application does not necessarily require all of the advantages described above to be achieved at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0026] Figure 1 A flow chart of the method for in-situ testing of metal micro-area combustion characteristics provided for this application;

[0027] Figure 2 This is a graph showing the surface morphology evolution of pure titanium particles obtained by the test method of Example 1 of the present application;

[0028] Figure 3 This is a graph showing the surface morphology evolution of a titanium sheet obtained by the test method of Example 2 of the present application;

[0029] Figure 4 This is a graph showing the evolution of the surface morphology of a titanium sheet obtained by the test method of Example 3 of the present application;

[0030] Figure 5 This is a surface morphology evolution diagram of 25Cr3Mo2WNiVNb obtained by the test method of Example 9 of the present application;

[0031] Figure 6 This is a diagram showing the surface morphology evolution of titanium particles obtained by the test method of Comparative Example 3. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0033] The present application provides a method for in-situ testing of metal micro-area combustion characteristics, such as Figure 1 As shown, the following steps are included:

[0034] S101: loading the in-situ heated sample rod containing the metal sample into a cabin of a transmission electron microscope, and adjusting the atmosphere in the cabin to a target atmosphere;

[0035] In the present application, a metal sample is placed in a chamber of a transmission electron microscope to achieve electron beam irradiation of the metal sample. The in-situ heating sample rod can heat the metal sample in-situ, improve the accuracy and stability of the heating temperature of the metal sample, and observe the morphology and structural changes of the metal sample during heating and electron beam irradiation without interference. In order to obtain the micro-area combustion characteristics of the metal sample under different target atmospheres, the atmosphere in the chamber can be adjusted, for example, to any one of a vacuum atmosphere, a pure oxygen atmosphere, or a mixed gas atmosphere.

[0036] The present application has no particular restrictions on the in-situ heating sample rod, as long as the invention purpose of the present application can be achieved, and the in-situ heating sample rod known in the art can be used. The present application has no particular restrictions on the transmission electron microscope, as long as the invention purpose of the present application can be achieved, and a commercially available transmission electron microscope can be used. The present application has no particular restrictions on the working parameters of the transmission electron microscope, as long as the invention purpose of the present application can be achieved, for example, the working voltage is 200kev~300kev.

[0037] S102: heating the metal sample to a predetermined temperature by in-situ heating the sample rod;

[0038] The present application first heats the metal sample to a predetermined temperature by an in-situ heating sample rod, realizes energy accumulation on the metal sample, and then causes the metal to burn in a micro-area by electron beam irradiation. The predetermined temperature of the present application can be pre-set based on the type and melting point of the metal sample. The predetermined temperature is lower than the melting point of the metal sample. This is because if the predetermined temperature is higher than or equal to the melting point of the metal sample, the sample as a whole will melt, and in-situ observation of the micro-area cannot be performed. In this way, it can be avoided that the metal sample undergoes a phase change before the electron beam irradiates the metal sample, thereby making the observation of the microscopic changes of the metal sample during micro-area combustion incomplete. The present application does not specifically limit the predetermined temperature range of different metals. For example, when the metal sample is titanium, the predetermined temperature can be 600-1670°C; when the metal sample is titanium alloy TC4, the predetermined temperature can be 600-1600°C; when the metal sample is 25Cr3Mo2WNiVNb steel, the predetermined temperature can be 700-1300°C.

[0039] S103: Irradiate the metal sample with an electron beam generated by a transmission electron microscope, and control the electron beam density to 800 A cm 2 ~6000A·cm 2 , the electron beam irradiation area is 200nm 2~1500nm 2 , so that the metal sample undergoes micro-combustion;

[0040] In this application, electron beam density refers to the electron flow rate per unit area per unit time of the electron beam that is gathered into a beam. Electron beam irradiation area refers to the actual area on the sample irradiated by the electron beam. Micro-area combustion refers to the combustion of a local micro-area of ​​the sample (such as the surface, interface, etc.) at the atomic scale, which is manifested as the formation of a cavity in the local micro-area after the energy reaches the critical condition, and the rapid migration of atoms near the cavity causes the cavity to expand rapidly.

[0041] Most of the metal combustion experiments currently used are open experiments, and the experimental data obtained can only perform a rough qualitative analysis of the macroscopic combustion behavior of the metal. Since the metal combustion caused by energy accumulation usually starts from a local micro-area, understanding the combustion behavior of the metal in the micro-area can more accurately analyze the combustion behavior of the metal. However, the current experimental means are difficult to obtain the combustion characteristics of the metal from the microscopic atomic scale, and it is difficult to achieve quantitative analysis such as the atomic migration rate of the interface reaction and the activation energy of the interface reaction. It is difficult to induce the combustion behavior of the metal by relying solely on the existing simple microstructure analysis methods such as transmission electron microscopy and scanning electron microscopy. Based on the above research, the inventors found that when the metal sample is heated to a predetermined temperature by an in-situ heating sample rod, and then an electron beam is used to irradiate the surface of the metal sample, and the parameters of the electron beam are controlled within the scope of this application, it is possible to provide a driving force for the interface, element, and phase changes on the surface of the metal sample at the nanometer scale, thereby inducing the micro-area combustion of the metal sample, and realizing the observation of changes in the metal sample at the submicron, nanometer, or even atomic scale, such as surface state, phase composition changes, atomic migration, interface migration, etc.

[0042] The inventors also found that when the electron beam density is too large (for example, greater than 6000 A·cm 2 ), or when the electron beam irradiation area is too small (e.g. less than 200nm 2 ), the energy is large, which can easily cause local melting of the sample, making it difficult to observe the phase change information of the sample; when the electron beam density is too small (for example, less than 800A·cm 2 ), or when the electron beam irradiation area is too large (for example, greater than 1500nm 2 ), the energy accumulation of the metal sample does not reach the critical value of combustion, and the metal combustion behavior cannot be induced. By collaboratively controlling the electron beam density and the electron beam irradiation area of ​​the transmission electron microscope within the above range, the micro-combustion of the metal sample can be effectively induced, so that the surface state, phase composition, atomic migration, interface migration, etc. of the metal sample during the micro-combustion process can be observed and recorded, and the combustion characteristics of the metal sample at the moment of micro-combustion can be obtained.

[0043] In the process from heating to ignition of the metal sample of the present application, a temperature measuring device can be used to monitor the surface temperature of the pure titanium particles of the metal sample in real time to improve the accuracy of the result. The present application has no particular restrictions on the temperature measuring device, as long as the purpose of the invention of the present application can be achieved. For example, the temperature measuring device is a thermocouple. The present application can maintain a certain length of time when the metal sample is irradiated by an electron beam. The present application has no particular restrictions on the length of time, as long as the metal sample can undergo micro-area combustion, for example, the length of time is 20s to 600s.

[0044] S104: Obtain the combustion characteristics of the metal sample at the moment when micro-area combustion occurs.

[0045] Combustion characteristics include: phase change information and interface migration direction. Phase change information refers to the critical conditions for phase change, phase change kinetic parameters, and reaction products, and interface migration direction refers to the normal direction of interface migration.

[0046] In the process of using electron beam to irradiate metal samples, the phase change information, interface migration and other information of the metal samples at the moment of micro-area combustion can be observed by transmission electron microscope, and the microtubule organization structure of the sample can be dynamically observed and recorded by using a camera device in high-resolution mode. This application does not impose any special restrictions on the camera device, as long as it can meet the requirements of the electron microscope and achieve the invention purpose of the application. For example, the camera device is a CCD (Charge-coupled Device) camera.

[0047] In the present application, while the metal sample is irradiated with an electron beam generated by a transmission electron microscope, real-time observation can be performed using the transmission electron microscope to obtain the surface state, phase composition, element migration, interface migration, etc. of the metal sample during the process from heating to ignition of the metal surface micro-area at the submicron, nanometer or atomic scale, thereby obtaining the combustion characteristics of the metal sample at the moment of micro-area combustion.

[0048] The present application provides a method for in-situ testing of metal micro-area combustion characteristics, which induces micro-area combustion of a metal sample by heating and electron beam irradiation, obtains phase change information and interface migration information of the metal sample at the moment of micro-area combustion, and then realizes the analysis of the combustion behavior of the metal at the microscopic atomic scale.

[0049] In one embodiment of the present application, the heating rate is 1°C / s to 5°C / s, preferably 1°C / s to 3°C / s. For example, the heating rate can be 1°C / s, 2°C / s, 3°C / s, 4°C / s, 5°C / s or a range between any two values. The inventors have found that when the heating rate to the predetermined temperature is within the above range, it is more conducive to the micro-combustion of the metal sample. This is because when the heating rate is too low (for example, lower than 1°C / s), the metal sample is prone to oxidation during the heating process to form an oxide film, which increases the energy required for the metal micro-combustion and reduces the clarity of the in-situ observation, especially for metals that are easily oxidized. The heating rate is not suitable for being too low; when the heating rate is too high (for example, higher than 5°C / s), the sample reaches the preset temperature in a short time, and the phase change information and interface migration information at the atomic scale react quickly, which is not conducive to fine in-situ observation. At the same time, there is a large thermal stress, which greatly interferes with the result analysis.

[0050] In one embodiment of the present application, the target atmosphere is a vacuum atmosphere, and the vacuum degree of the vacuum atmosphere is 2×10 -5 mbar~7×10 -6 mbar, thus realizing in-situ analysis of the micro-combustion behavior of metals in a high vacuum environment.

[0051] In another embodiment of the present application, the target atmosphere is a mixed gas atmosphere, and the mixed gas atmosphere is a mixed gas composed of oxygen and nitrogen in a volume ratio of 1:0.2 to 4. By controlling the target atmosphere to be the above atmosphere, in-situ analysis of the micro-combustion behavior of metals in a mixed atmosphere containing oxygen is achieved.

[0052] The present application does not limit the material of the metal sample, which can be any metal material that can burn or a mixture of multiple metal materials; in one embodiment of the present application, the metal sample is selected from any one of titanium, titanium alloy, iron, iron alloy, magnesium, magnesium alloy, nickel, and nickel alloy. The method of in-situ testing of metal micro-area combustion characteristics in the present application can test different metal samples that can burn.

[0053] The present application does not impose any special restrictions on the physical form of the metal sample, as long as the purpose of the invention of the present application can be achieved; in one embodiment of the present application, the metal sample is a metal nanoparticle or a metal nanosheet, wherein the metal nanosheet can be a thin film sample prepared by a focused ion beam. The present application does not impose any special restrictions on the size of the metal nanoparticles, as long as the purpose of the present invention can be achieved. For example, the average particle size of the metal nanoparticles is 5nm to 100nm. The present application does not impose any special restrictions on the size of the metal nanosheet, as long as the purpose of the present invention can be achieved. For example, the size of the metal nanosheet is 20nm to 90nm. When the metal sample is placed on the in-situ heating sample rod, the parameters such as the crystal orientation of the metal sample can be recorded, and the relevant parameters of the metal sample can be input into the in-situ heating control system during the heating process, which can improve the clarity of the in-situ observation image, and at the same time can reduce the error between the sample heating temperature and the preset temperature, thereby improving the accuracy of the activation energy of the interface reaction. Among them, the relevant parameters include crystal orientation, metal sample thickness, heating coil resistance, etc. The present application records the crystal orientation of the metal sample, which is conducive to the analysis of the combustion mechanism of the metal micro-area.

[0054] In one embodiment of the present application, irradiating the metal sample with an electron beam generated by a transmission electron microscope includes: irradiating an edge region of the metal sample with an electron beam generated by a transmission electron microscope.

[0055] The inventors have found that using an electron beam to irradiate the edge area of ​​a metal sample can more easily induce micro-combustion, which is more conducive to analyzing the combustion behavior of the metal at the microscopic atomic scale.

[0056] In one embodiment of the present application, after step S104, the method for in-situ testing of metal micro-region combustion characteristics of the present application further includes: calculating the interface reaction activation energy and migration rate of the metal sample using the combustion characteristics.

[0057] By calculating the minimum electron beam energy required for metal micro-combustion, the energy threshold value for metal micro-combustion can be obtained. Then, by recording the distance and time of interfacial migration on the metal surface, the interfacial migration rate and activation energy at different temperatures can be obtained.

[0058] In this application, the energy threshold of metal micro-combustion may refer to the minimum electron beam energy that can cause the metal sample to undergo micro-combustion reaction. When the energy of the electron beam irradiating the metal sample exceeds the energy threshold of metal micro-combustion, the distance of interface migration (L) of the same metal sample at different temperatures is recorded. t -L 0 ) and the elapsed time (tt 0 ), the following first expression can be used to calculate the atomic migration rate of the interface reaction:

[0059]

[0060] Where V represents the atomic migration rate of the interface reaction, L t is the vertical distance from the starting interface after the interface migration time t, L 0 is the interface migration time t 0 The vertical distance from the starting interface, t is the distance from the interface to L t The time elapsed, t 0 Migrate to L 0 The time elapsed.

[0061] Based on the atomic migration rate of the interface reaction under different temperature conditions, the following second expression can be used to fit -ln(VT 2 )and The slope of the curve is used to calculate the activation energy of the interface reaction of metal micro-combustion:

[0062]

[0063] Among them, E a represents the activation energy of the interface reaction, V is the atomic migration rate of the interface reaction, T is the predetermined temperature, A is a constant, and R is the molar constant.

[0064] For the same metal sample, the same interface reaction activation energy E at different predetermined temperatures a Then, the interface reaction atomic migration rate V at different temperatures can be obtained by the first expression, and the interface reaction activation energy E can be obtained by the second expression. a .

[0065] The present application provides a method for in-situ testing of metal micro-area combustion characteristics, which induces micro-area combustion of metal samples through the combined action of in-situ heating of sample rods and electron beam irradiation, obtains phase change information and interface migration information of metal samples at the moment of micro-area combustion, and then realizes the analysis of the combustion behavior of metals at the microscopic atomic scale. The method for in-situ testing of metal micro-area combustion characteristics of the present application breaks through the shortcomings that existing macroscopic testing methods cannot obtain material combustion characteristics from the microscopic atomic scale, and existing simple microstructural analysis methods based on transmission electron microscopy, scanning electron microscopy, etc. cannot induce metal combustion; through the systematic study of micro-area combustion behavior, the energy transfer and accumulation mechanism of metal surface micro-areas can be clarified, and the ignition mechanism of metal micro-areas can be deeply revealed, which has important guiding significance for establishing a thermodynamic model for metal micro-area ignition and clarifying the ignition threshold value and influencing factors of metal micro-areas.

[0066] Example

[0067] Hereinafter, the embodiments of the present application will be described in more detail with reference to Examples and Comparative Examples. Various tests and evaluations were performed according to the following methods.

[0068] Example 1

[0069] (1) Place the heating chip containing pure titanium particles with an average particle size of 60 nm into the in-situ heating sample holder (model: Gatan652), and then place the in-situ heating sample holder into a vacuum chamber with a degree of vacuum of 2×10 -5 Inside the cabin of mbar's transmission electron microscope (model: Titan ETEM G2), the operating voltage was controlled to 300kev, and a suitable observation position was found at 300,000 times magnification;

[0070] (2) heating the sample rod in situ to a predetermined temperature of 1100°C at a heating rate of 3°C / s;

[0071] (3) When the temperature and gas flow field are stable, open the vacuum valve of the transmission electron microscope and use the electron beam generated by the transmission electron microscope to irradiate the pure titanium particles. The electron beam density is controlled to 800 A cm 2 , the electron beam irradiation area is 450nm 2 , thereby irradiating a local area of ​​the pure titanium particles with a fixed dose of electron beam for 30 seconds to cause micro-combustion of the pure titanium particles; at the same time, from the beginning of electron beam irradiation of the pure titanium particles to the micro-combustion of the pure titanium particles, a CCD camera (model: SLBG-DCU223) was used to dynamically observe and record the microstructure of the sample at high resolution, and from the in-situ heating of the sample rod to the micro-combustion of the pure titanium particles, a temperature measuring device was used to monitor the surface temperature of the pure titanium particles of the metal sample in real time.

[0072] Embodiments 2 to 9

[0073] Except for adjusting the test parameters as shown in Table 1, the rest are the same as Example 1, wherein the test parameters include metal sample, target atmosphere, target atmosphere pressure, predetermined temperature, heating rate, electron beam density, and electron beam irradiation area.

[0074] Comparative Examples 1 to 3

[0075] Except for adjusting the test parameters as shown in Table 1, the rest are the same as Example 1, wherein the test parameters include metal sample, target atmosphere, target atmosphere pressure, predetermined temperature, heating rate, beam spot size, and electron beam irradiation area.

[0076] Table 1

[0077]

[0078] It can be seen from Examples 1 to 9 and Comparative Examples 1 to 3 that by adopting the method for in-situ testing of metal micro-area combustion characteristics provided in the present application, when the electron beam density, the electron beam irradiation area, and the heating rate are within the range of the present application, interfacial migration can occur on the surface of the metal sample, thereby achieving micro-area combustion of the metal sample.

[0079] Specifically, from Figure 2 It can be seen that the micro-area atomic activity of pure titanium particles increases during the energy accumulation process, causing micro-area combustion to occur instantly and accompanied by the rapid migration of interface atoms. This shows that under high vacuum conditions, the energy accumulation of the electron beam reaches the energy threshold of metal micro-area combustion, which can induce atomic-level micro-area combustion mutations and produce micro-area combustion behavior.

[0080] from Figure 3 It can be seen that under the test conditions of Example 2, the titanium sheet undergoes interface migration in the surface micro-region after being irradiated by electron beam. Figure 3 The morphology evolution of the medium-purity titanium sheet sample during electron beam irradiation is as follows: Figure 3 In the process from (a) to (b), the interface reaction atom migration rate can be obtained according to the first expression: 1.61nm / s; In the process from (b) to (c), the interface reaction atom migration rate can be obtained according to the first expression: ; From (a) to (c), the interface reaction atom migration rate can be obtained according to the first expression: , calculated V 1 、V 2 and V 3 The average value of (d) shows that under the above test conditions, the atomic migration rate of the interface reaction in the micro-region of the titanium sheet surface induced by the electron beam is 1.30nm / s. By analyzing (d), the migration surface of the titanium sheet surface micro-region can be obtained as Migration direction

[0081] After obtaining the atomic migration rate of the interface reaction of the titanium sheet, the activation energy of the interface reaction can be further calculated according to the second expression, specifically: by fitting the atomic migration rate of the interface reaction at different temperatures -ln(VT 2 )and The slope of the curve is The activation energy of the interfacial reaction for micro-combustion of metal is calculated by multiplying the slope by the molar gas constant R.

[0082] from Figure 4 It can be seen that under the test conditions of Example 3, the titanium sheet undergoes interface migration in the surface micro-region after being irradiated by electron beam. Figure 4 The morphology evolution of the medium-purity titanium sheet sample during heating is as follows: Figure 4In the process from (a) to (b), the interface reaction atom migration rate can be obtained according to the first expression: 0.32nm / s; In the process from (b) to (c), the interface reaction atom migration rate can be obtained according to the first expression: ; From (a) to (c), the interfacial reaction atom migration rate can be obtained according to the first expression: , calculated V 1 、V 2 and V 3 The average value of (d) shows that under the above test conditions, the atomic migration rate of the interface reaction in the micro-region of the titanium sheet surface induced by the electron beam is 0.26nm / s. By analyzing (d), the migration surface of the titanium sheet surface micro-region can be obtained as , migration direction

[0083] After obtaining the atomic migration rate of the interface reaction of the titanium sheet, the activation energy of the interface reaction can be further calculated according to the second expression, specifically: by fitting the atomic migration rate of the interface reaction at different temperatures -ln(VT 2 )and The slope of the curve is The activation energy of the interfacial reaction for micro-combustion of metal is calculated by multiplying the slope by the molar gas constant R.

[0084] from Figure 5 It can be seen that the energy generated by electron beam irradiation reaches the threshold value for ignition of 25Cr3Mo2WniVNb. Grain boundary migration, i.e. micro-combustion, occurs at 700°C in 25Cr3Mo2WniVNb. Large holes are left behind after grain boundary migration, leaving austenite. This indicates that the micro-atomic activity of 25Cr3Mo2WniVNb increases during the energy accumulation process, causing 25Cr3Mo2WniVNb to burn instantly at a temperature far below the melting point (the melting point of 25Cr3Mo2WniVNb is 2500°C), accompanied by rapid migration of interface atoms.

[0085] Figure 6 The surface morphology evolution diagram of titanium particles obtained by the test method of Comparative Example 3, wherein (a) is the morphology of titanium particles before heating, and (b) is the morphology of titanium particles after heating. Figure 6 It can be seen that the titanium particles did not undergo micro-area combustion. This may be due to the slow heating rate under the test conditions of Comparative Example 3. During the heating process, the titanium sheet has been oxidized to form an oxide film, which increases the energy required for the titanium sheet to burn.

[0086] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0087] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0088] The above description is only a preferred embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. A method for in-situ testing of metal micro-area combustion characteristics, It is characterized in that Includes steps: The in-situ heated sample rod containing the metal sample is loaded into a chamber of a transmission electron microscope, and the atmosphere in the chamber is adjusted to a target atmosphere, wherein the target atmosphere is a vacuum atmosphere, a pure oxygen atmosphere, or a mixed gas atmosphere; The metal sample is heated to a predetermined temperature by the in-situ heating sample rod, wherein the predetermined temperature is lower than the melting point of the metal sample, and the heating rate is 1°C / s to 5°C / s; Irradiate the metal sample with an electron beam generated by the transmission electron microscope, and control the electron beam density to be 800 A·cm 2 ~6000 A·cm 2 , with an electron beam irradiation area of 200 nm 2 ~1500 nm 2 , so that micro-area combustion occurs in the metal sample; Obtaining the combustion characteristics of the metal sample at the moment of micro-area combustion, wherein the combustion characteristics include: phase change information and interface migration direction; Calculating the interface reaction atom migration rate and interface reaction activation energy of the metal sample using the combustion characteristics; The interface reaction atom migration rate is calculated using the following first expression: ， Among them, represents the atomic migration rate of the interfacial reaction, is the interfacial migration time and the vertical distance from the starting interface after is the interfacial migration time and the vertical distance from the starting interface after is the time elapsed when the interface migrates to and is the time elapsed when the interface migrates to ; The activation energy of the interface reaction is calculated using the following second expression: ， in, represents the activation energy of the interfacial reaction, is the atomic migration rate of the interface reaction, is the predetermined temperature, is the pre-exponential factor, is the molar constant.

2. The method according to claim 1, It is characterized in that The vacuum degree of the vacuum atmosphere is 2×10 -5 mbar~7×10 -6 mbar; the mixed gas atmosphere is a mixture of oxygen and nitrogen in a volume ratio of 1:0.1-4.

3. The method according to claim 1, It is characterized in that The metal sample is selected from any one of titanium, titanium alloy, iron, iron alloy, magnesium, magnesium alloy, nickel and nickel alloy.

4. The method according to claim 1, It is characterized in that The metal sample is metal nanoparticles or metal nanosheets.

5. The method according to claim 1, It is characterized in that The irradiating the metal sample with an electron beam generated by the transmission electron microscope comprises: The edge region of the metal sample is irradiated by an electron beam generated by the transmission electron microscope.

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