Device and method for measuring diffusion coefficient of bulk amorphous alloy under low temperature environment

Abstract

The application discloses a device and method for measuring bulk amorphous alloy diffusion coefficient in a low-temperature environment, and relates to the technical field of amorphous alloy thermophysical property testing. The device comprises a vacuum chamber and an environment bin, the environment bin is located in the vacuum chamber, the top of the environment bin is communicated with the vacuum chamber, and the bottom is provided with a cooling medium channel in communication; a laser gap detection device is located in the environment bin and arranged on the two sides of a bulk amorphous alloy sample to be measured; and an adjusting mechanism is located in the environment bin and used for loading or unloading the bulk amorphous alloy sample to be measured and changing the stress between the amorphous alloy samples by controlling the position of the upper sample of the bulk amorphous alloy sample to be measured. The application can change the temperature of the environment bin, realize the measurement of the surface diffusion coefficient of the amorphous alloy under different temperature conditions, and for the first time introduces the surface roughness of the amorphous alloy into a model, so that the precision of the diffusion coefficient measurement is improved.

Description

Technical Field

[0001] This invention relates to the field of thermophysical property testing technology for amorphous alloys, and in particular to an apparatus and method for measuring the diffusion coefficient of bulk amorphous alloys under low-temperature conditions. Background Technology

[0002] Amorphous alloys are materials with long-range disorder in their atomic structure. When molten metal is rapidly cooled at high temperatures, the solidified material retains the disordered structure of the liquid, thus forming an amorphous alloy. Due to this unique atomic structure, amorphous alloys have lower density and exhibit special physical, chemical, and other properties compared to crystalline materials of the same composition, as well as different kinetic behaviors.

[0003] Numerous experiments have confirmed that the surface of amorphous alloys exhibits dynamic characteristics distinct from their interior. Microscopic characterization methods (nanoscale), such as electron correlation spectroscopy and high-resolution transmission electron microscopy, allow direct observation of atomic motion in nanoscale samples. By characterizing parameters like diffusion coefficient and relaxation time, it has been discovered that the surface of low-dimensional amorphous alloys (nanoparticles, nanorods) possesses dynamic characteristics far faster than their interiors. For mesoscale amorphous alloys, such as micrometer-sized amorphous alloy films, relatively mature methods exist for characterizing their surface dynamics. These methods involve pre-setting specific surface structures, such as gratings, and calculating the diffusion coefficient by measuring the evolution of the surface morphology of mesoscale amorphous alloys. However, this method cannot measure crucial parameters such as the surface diffusion coefficient of low-temperature and bulk amorphous alloys.

[0004] The existing measurement techniques related to the method for measuring the surface diffusion coefficient of amorphous alloys in this patent mainly include:

[0005] I. By presupposing a special surface structure of amorphous alloys and utilizing the diffusion motion of the amorphous alloy surface after heating, the morphology evolution is observed using atomic force microscopy after a certain period of time, and the diffusion coefficient of the amorphous alloy surface is derived (High surfacemobility and fast surface enhanced crystallization of metallic glass, Appl. Phys. Lett. 107, 141606, 2015).

[0006] However, methods for measuring amorphous alloys using surface morphology are mainly limited in two aspects:

[0007] 1. Because this process requires observing surface morphology to study the surface diffusion coefficient, and due to limitations in the accuracy of observational characterization methods, amorphous alloys typically require long-term annealing. The annealing temperature is generally 0.9T. g Currently, for most amorphous alloy systems, 0.9Tg The corresponding temperature is 540K, which is 267℃ (T). g (Often higher than 600K). The diffusion coefficient measured under these temperature conditions corresponds to 0.9T. g The diffusion coefficient at temperature. For metastable materials like amorphous alloys, the diffusion behavior is quite unique. According to reported experimental results, the diffusion coefficient and viscosity conform to the Einstein-Stokes relation at temperatures much higher than the melting point. However, as the temperature decreases, this relation evolves into a fractal Einstein-Stokes relation, i.e.

[0008]

[0009] When ξ equals 1, it is called the standard Einstein-Stokes relation; as the temperature decreases, the ξ exponent decreases, and the exponent is approximately 0.5. However, to date, the lowest characterization temperature is 0.8T. g Therefore, this method cannot be used to characterize the surface diffusion behavior of amorphous alloys under low-temperature conditions.

[0010] 2. The method of obtaining the surface diffusion coefficient through changes in surface morphology requires knowledge of the relevant physical properties of the material, including surface energy, atomic volume and atomic number density. These parameters are relatively well-established for single-component metal systems, but are difficult to obtain for multi-component amorphous alloy systems.

[0011] II. Chinese Patent Publication No. CN 108333103 A discloses a method and apparatus for testing the adhesion coefficient of friction pair materials, such as... Figure 1 As shown, the basic principle of the test is as follows: Coil 5 is energized, generating a magnetic field opposite to that of magnet 6. The repulsive force between 5 and 6 causes sample 4 to contact sample 3 at the upper end. After a certain contact time, energizing coil 8 generates a force that, through the opposite magnetic field to magnet 6, separates sample 4 from sample 3. The voltage value of coil 8 at the instant of disconnection is recorded to calculate the magnitude of the separation force. The adhesion coefficient is calculated as the ratio of the normal stress corresponding to the voltage applied to coil 5.

[0012] Based on the method for measuring separation force and adhesion coefficient in the aforementioned patent, the diffusion coefficient of amorphous alloys under room temperature conditions can be measured (Strong adhesion induced by liquid-like surface of metallic glasses, Appl. Phys. Lett. 120, 051601, 2022). In the process of calculating the surface diffusion coefficient of amorphous alloys, this patent obtains an approximate time required for the surface gap to be filled by diffusion alone without positive pressure. However, in Equation (4), the surface area of ​​a perfectly flat surface is used to obtain the surface diffusion coefficient, which has a large deviation from the actual surface area of ​​the sample surface. Summary of the Invention

[0013] This invention provides an apparatus and method for measuring the diffusion coefficient of bulk amorphous alloys under low-temperature conditions, aiming to solve the problems existing in the background art. By studying the surface diffusion coefficient of bulk amorphous alloys under low-temperature conditions, the invention designs a method to measure the diffusion coefficient using the surface bonding characteristics of amorphous alloys. The testing principle is that the amorphous alloy surfaces are brought into contact under ultra-high vacuum conditions. Due to surface diffusion, the atoms of the two metal surfaces diffuse and bond together. The surface diffusion coefficient can be calculated by measuring the surface bonding strength.

[0014] To achieve the above technical objectives, this application mainly adopts the following technical solution:

[0015] In a first aspect, this application provides an apparatus for measuring the diffusion coefficient of bulk amorphous alloys at low temperatures, comprising,

[0016] A vacuum chamber that provides a vacuum environment for the measuring device;

[0017] An environmental chamber is located inside a vacuum chamber. The top of the environmental chamber is connected to the vacuum chamber, and the bottom is connected to a cooling medium channel to provide different ambient temperatures inside the environmental chamber according to the flow rate of the cooling medium.

[0018] A laser gap detection device is located inside the environmental chamber and is set on both sides of the amorphous alloy sample to be tested.

[0019] An adjustment mechanism, located within the environmental chamber, is used to control the loading or unloading of stress between the amorphous alloy samples to be tested, and to achieve stress changes by controlling the position of the samples.

[0020] In some embodiments, the adjustment mechanism has a movable end, and two amorphous alloy samples to be tested are arranged facing each other vertically. The movable end is fixedly connected to the upper amorphous alloy sample to be tested. The adjustment mechanism controls the position of the upper amorphous alloy sample to be tested to achieve the loading or unloading of stress between the two amorphous alloy samples to be tested.

[0021] In some embodiments, the adjustment mechanism is a mechanical testing machine; a temperature sensor is also provided inside the environmental chamber.

[0022] Secondly, this application provides a method for measuring the diffusion coefficient of bulk amorphous alloys in a low-temperature environment, comprising the following steps:

[0023] S1: Calculate the stable surface area A of the contact region of the bulk amorphous alloy sample to be tested. f ;

[0024] S2: Calculate the critical separation force F between the amorphous alloy samples under test when the preset temperature T is reached. * Furthermore, when an external force L = 0 is applied to the amorphous alloy sample under test, the corresponding critical holding time t is... L＝0 ;

[0025] S3: Calculate the diffusion coefficient of the bulk amorphous alloy sample to be tested.

[0026]

[0027] Furthermore, in step S1, the stable surface area A of the contact region of the amorphous alloy sample to be tested is calculated. f It includes the following steps:

[0028] S11: After pre-treating the surface of the amorphous alloy sample to be tested, the surface morphology of the sample is measured, and the height value of the region is measured at a single pixel to establish a height distribution matrix h. xy ;

[0029] S12: Measure the true surface area A of the bulk amorphous alloy sample based on the height difference between the ideal smooth plane and the real plane. * In this paper, an ideal smooth plane refers to a completely smooth plane without any undulations; a real plane refers to a plane that reflects the true appearance of the amorphous alloy sample to be tested.

[0030] S13: Based on surface area A * The stable surface area A of the contact region is derived by observing the variation of different contact-separation cycle numbers. f .

[0031] Furthermore, in step S11, the pretreatment includes polishing and grinding the surface of the amorphous alloy sample to be tested.

[0032] Furthermore, in step S11, an atomic force microscope (AFM) is used to measure the surface of the amorphous alloy sample to be tested. Based on the scanning resolution measurement parameters of the AFM, a height distribution matrix h is established. xy .

[0033] Furthermore, in step S12, the true surface area A of the contact area of ​​the amorphous alloy sample to be tested is measured. * Includes the following steps:

[0034] S121: Measure the surface of the bulk amorphous alloy sample under test in the initial state of the amorphous alloy without contact-separation cycle, and use the surface result measured at the maximum scanning resolution as the initial planar morphology state of the bulk amorphous alloy sample under test, and record the height value of a single pixel point of the surface morphology of the bulk amorphous alloy sample under test at this time.

[0035] S122: The true surface area A of the contact region of the bulk amorphous alloy sample under test. * for:

[0036]

[0037] Where A* is the true surface area of ​​the contact region of the amorphous alloy sample under test, A is the surface area of ​​the corresponding ideal smooth plane, c is the AFM parameter, which is numerically equal to the side length of the single smallest characterization dimension, and u(h x，y ) is a step function, when h x，y >0, u(h) x，y ) = 1, when h x，y ≤0, u(h) x，y ) = 0.

[0038] Furthermore, in step S13, the stable surface area A of the contact region of the amorphous alloy sample to be tested is derived. f It also includes the following steps:

[0039] S131: Measure the planar morphology of the amorphous alloy sample after one contact-separation and record the height value of a single pixel on the surface morphology of the amorphous alloy sample at this time.

[0040] S132: Calculate the surface area A of the amorphous alloy after one contact-separation process. * 1;

[0041] S133: Calculate the surface area A of the amorphous alloy after 2, 5, 10, 20, and 50 contact-separation cycles.* 2, A * 5, A * 10 A * 20 A * 50 The number of contact-separation cycles is not limited to 50 and can be determined according to the actual situation; the true surface area of ​​the contact region of the block amorphous alloy sample under test after CSC contact-separation cycles is fitted.

[0042]

[0043] in, This represents the true surface area of ​​the contact region of the amorphous alloy sample under test after fitting.

[0044] S134: Based on the above evolutionary rules, select the equilibrium segment. The stable surface area A of the amorphous alloy surface f The corresponding number of contact-separation cycles is f.

[0045] In some embodiments, in step 2, the critical hold time t L＝0 The calculation process is as follows:

[0046] Take two amorphous alloy samples to be tested, arrange them vertically and face each other, and place the amorphous alloy samples to be tested in a vacuum environment to reach the preset temperature value T.

[0047] The amorphous alloy sample to be tested at the upper end is controlled to move downward. After f separation-contact cycles, the external force L is adjusted to reach the preset value, and this loading state is maintained for t time.

[0048] Control the upper part of the amorphous alloy sample to be tested to move upward at a constant strain rate, record the force-displacement curve, and find the magnitude of the external force value of the first discontinuity of the curve based on the force-displacement curve, and record the separation force F under this condition.

[0049] Multiple contact-separation cycle experiments were conducted to determine the relationship between the separation force F, the holding time t, and the external force L under the same temperature conditions. Based on this relationship, it was deduced that when the critical F is reached... * And when the external force L = 0, the corresponding critical holding time t L＝0 .

[0050] In this application, the vacuum environment of the vacuum chamber is 10. -7 Pa, where the cooling medium is liquid nitrogen.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. The measuring device of the present invention can change the temperature of the ambient chamber to measure the surface diffusion coefficient of amorphous alloys under different temperature conditions;

[0053] 2. This invention is the first to incorporate the surface roughness of amorphous alloys into the model, thereby improving the accuracy of diffusion coefficient measurement;

[0054] 3. This invention uses a mechanical testing machine to accurately reflect the relationship between force and displacement, thus improving the accuracy of the measurement. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the structure of a testing device for the adhesion coefficient of friction pair materials in the prior art;

[0056] Figure 2 A schematic diagram of a device for measuring the diffusion coefficient of bulk amorphous alloys in a low-temperature environment, provided in an embodiment of the present invention;

[0057] Figure 3 An AFM morphology image of an amorphous alloy surface provided in an embodiment of the present invention;

[0058] Figure 4 A graph showing the change in surface area of ​​an amorphous alloy with the number of contact-separation cycles provided in an embodiment of the present invention;

[0059] Figure 5 Force-displacement diagram of the amorphous alloy separation process provided in the embodiments of the present invention;

[0060] Figure 6 The bulk amorphous alloy Cu provided in the embodiments of the present invention 46 Zr 46 The variation law of separation force of Al8 under different positive pressures and contact times and the fitted linear graph. Detailed Implementation

[0061] The present invention will be further described below through embodiments. It should be understood that these embodiments are only for illustrating the purpose of the present invention and are in no way limiting the scope of the present invention.

[0062] Example 1

[0063] To measure the surface diffusion coefficient of bulk amorphous alloys within different temperature ranges, this invention provides the following apparatus, the specific structure of which is as follows: Figure 2 As shown.

[0064] The apparatus for measuring the diffusion coefficient of bulk amorphous alloys at low temperatures includes,

[0065] Vacuum chamber 8 provides a vacuum environment for the measuring device;

[0066] The environmental chamber 5 is located inside the vacuum chamber 8. The top of the environmental chamber 5 is connected to the vacuum chamber 8, and the bottom is connected to a cooling medium channel 6 to provide different ambient temperatures inside the environmental chamber 5 according to the flow rate of the cooling medium.

[0067] The laser gap detection device 4 is located inside the environmental chamber 5 and is symmetrically distributed on both sides of the amorphous alloy sample to be tested.

[0068] The adjustment mechanism 3, located inside the environmental chamber 5, has a movable end. This adjustment mechanism is used to control the loading or unloading of stress between the amorphous alloy samples to be tested, and to achieve stress changes by controlling the position of the samples.

[0069] Two amorphous alloy samples were selected for testing and arranged facing each other vertically.

[0070] A preferred approach is to symmetrically distribute the laser gap detection device 4 on both sides of the contact surface of the two amorphous alloy samples to be tested.

[0071] In addition, the movable end of the adjustment mechanism 3 is fixedly connected to the amorphous alloy sample 1 to be tested arranged at the upper end. The position of the amorphous alloy sample 1 to be tested at the upper end is controlled by the adjustment mechanism 3 to realize the loading or unloading of external force between the two amorphous alloy samples to be tested. In this application, specifically, the adjustment mechanism 3 adopts a pressure testing machine. The mechanical testing machine can accurately reflect the relationship between force and displacement, thus improving the measurement accuracy.

[0072] A temperature sensor 7 is also installed inside the environmental chamber 5 of the measuring device of this application, which can sense the actual temperature inside the environmental chamber 5.

[0073] In operation, to achieve different low-temperature environments, a low-temperature heat transfer medium (such as liquid nitrogen) can be introduced into the environmental chamber 5 through the cooling medium channel 6, and the temperature can be detected by the temperature sensor 7. Different low-temperature conditions can be achieved by controlling parameters such as flow rate. The cooling medium channel 6 can be configured as a circulating pipeline, which helps to save cooling medium and is economical and environmentally friendly.

[0074] Example 2

[0075] This invention provides a method for measuring the diffusion coefficient of bulk amorphous alloys at low temperatures. Using the measuring device provided in Example 1, the measurement is performed through the following steps:

[0076] 1. Prepare a cylindrical amorphous alloy sample with a diameter of 2 mm, and grind and polish its surface.

[0077] 2. Measuring the surface diffusion coefficient of the bulk amorphous alloy sample requires calculating the surface area of ​​its contact region. This application incorporates surface roughness into the surface area model, first considering the surface of the amorphous alloy in its initial state before the contact-separation cycle. The surface morphology of this initial state is measured using the maximum scanning resolution of AFM, obtaining the AFM morphology image of the surface of the amorphous alloy sample in its initial state before the contact-separation cycle, as shown below. Figure 3 As shown.

[0078] The maximum scanning resolution of AFM measurement is 256×256 (the minimum resolution unit size corresponding to a 5μm range is 19.5nm). Figure 3 Each individual pixel in the matrix represents the height value of that region. A height distribution matrix h is then constructed using the height value of each pixel. x，y :

[0079]

[0080] 3. Calculate the true surface area of ​​the amorphous alloy sample before contact-separation testing:

[0081]

[0082] Where A* is the true surface area of ​​the contact region of the bulk amorphous alloy sample under test, A is the surface area of ​​the ideal smooth plane, c is the AFM parameter, which is numerically equal to the side length of the single minimum characterization size (the minimum resolution size per unit area corresponding to a range of 5 μm is 19.5 nm), u(h x，y ) is a step function, when h x，y >0, u(h) x，y ) = 1, when h x，y ≤0, u(h) x，y ) = 0.

[0083] 4. Using the same external force state, perform multiple contact-separation cycles on the bulk amorphous alloy sample to be tested; statistically analyze the change in surface area after different numbers of contact-separation cycles (CSC), as shown in the graph. Figure 4 As shown, the surface area after CSC contact-separation cycle processing is obtained through fitting:

[0084]

[0085] Where a and b are fitting constants. Figure 4 It can be seen that after a certain number of cycles, the surface area of ​​the amorphous alloy sample to be tested tends to reach equilibrium. Therefore, the surface area of ​​the equilibrium section is selected as the stable surface area A of the final sample test. f Record the corresponding number of contact-separation cycles as f.

[0086] 5. Fix the upper part of the amorphous alloy sample 1 to be tested on the movable end of the mechanical testing machine, and fix the lower part of the amorphous alloy sample 2 to be tested on the other end.

[0087] 6. Evacuate to 10 -7 Pa adjusts the temperature by controlling the flow rate of liquid nitrogen and other media in the cooling medium channel 6, and the temperature reaches the preset temperature value T by the reading of the temperature sensor 7.

[0088] 7. Control the moving end of the mechanical testing machine to drive the amorphous alloy sample 1 to be tested at the upper end to move downward. After contact-separation f times, adjust the external force L between the two samples again to reach the preset value.

[0089] 8. Maintain the loading state and sustain it for duration t;

[0090] 9. Turn on the laser gap detection device 4, control the mechanical testing machine to move upward at a constant quasi-static low strain rate, and record the force-displacement curve of the amorphous alloy separation process; (e.g.) Figure 5 As shown, find the first-order discontinuous external force value (Critical Point), and denote it as the separation force F under this state condition;

[0091] 10. Conduct multiple experiments to test the force (F) corresponding to different temperatures (T), different loading stresses (L), and different holding times (t).

[0092] 11. Under the same temperature conditions, derive the relationship between the separation force F, the holding time t, and the normal stress L:

[0093] F = f(t, L) (3)

[0094] By fitting the above relationship, we can deduce the critical value F that needs to be reached. * Furthermore, the applied stress is 0, i.e., L = 0, corresponding to the critical time t. L＝0 ;

[0095] 12. Substituting into formula (4), the diffusion coefficient of the bulk amorphous alloy sample to be tested can be measured.

[0096]

[0097] Using the methods mentioned above, the bulk amorphous alloy Cu was measured. 46 Zr 46 The separation forces on the Al8 surface under normal pressures of 78, 85, 110, 160, 200, 250, and 300 mN and contact times of 1, 5, 10, 30, and 120 min are shown in the following figures. Figure 6 As shown in Figure a.

[0098] A separation force of 24 mN was chosen as the critical value F. * It will reach the critical value F * The required contact time was statistically analyzed and fitted, such as... Figure 6 As shown in b, we can obtain:

[0099] L * = -1.67t * +316.67 (5)

[0100] Among them, L * Corresponding to the critical external force, t * Let L be the critical contact time. * A value of zero indicates surface adhesion achieved solely through the movement of atoms without any external force, corresponding to a time of 190 minutes. Based on the surface morphology evolution model obtained in step 4: Take A... f Cu is a bulk amorphous alloy 46 Zr 46 The surface area of ​​Al8 is 3.28 mm. 2 Therefore, the diffusion coefficient can be obtained as:

[0101]

[0102] Where A is the bulk amorphous alloy Cu 46 Zr 46 The actual surface area of ​​the Al8 contact region t corresponding to L=0 * (190 min). From this, the surface diffusion coefficient of the bulk amorphous alloy can be calculated to be 2.8 × 10⁻⁶. -10 m 2 ·s -1 .

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for measuring the diffusion coefficient of bulk amorphous alloys under low-temperature conditions, characterized in that, Includes the following steps: S1: Calculate the stable surface area of ​​the contact region of the bulk amorphous alloy sample under test. A f ; S2: Calculate the temperature when the preset value is reached. T Under these conditions, the separation force between the bulk amorphous alloy samples to be tested reaches the critical separation force. Furthermore, an external force is applied to the bulk amorphous alloy sample to be tested. L When = 0, the corresponding critical hold-up time ; S3: Calculate the diffusion coefficient of the bulk amorphous alloy sample to be tested. ； In step S1, the surface area of ​​the stable surface of the contact region of the amorphous alloy sample to be tested is calculated. A f It includes the following steps: S11: After pre-treating the surface of the amorphous alloy sample to be tested, the surface morphology of the sample is measured. The height value of the region is measured at a single pixel point to establish a height distribution matrix. h xy ; S12: Measure the true surface area of ​​the contact region of the bulk amorphous alloy sample based on the height difference between the ideal smooth plane and the real plane of the sample. A * ; S13: Based on the actual surface area A * Based on the variation of different contact-separation cycle numbers, the stable surface area of ​​the contact region of the bulk amorphous alloy sample under test is derived and calculated. A f .

2. The method for measuring the diffusion coefficient of bulk amorphous alloys under low-temperature conditions according to claim 1, characterized in that, In step S11, the pretreatment includes polishing and grinding the surface of the amorphous alloy sample to be tested.

3. The method for measuring the diffusion coefficient of bulk amorphous alloys under low-temperature conditions according to claim 1, characterized in that, In step S11, the surface of the bulk amorphous alloy sample to be tested is measured using an atomic force microscope (AFM). Based on the scanning resolution measurement parameters of the AFM, a height distribution matrix is ​​established. h xy .

4. The method for measuring the diffusion coefficient of bulk amorphous alloys under low-temperature conditions according to claim 1, characterized in that, In step S12, the true surface area of ​​the contact region of the amorphous alloy sample to be tested is measured. A * It includes the following steps: S121: Measure the surface of the bulk amorphous alloy sample under test in the initial state of the amorphous alloy without contact-separation cycle, and use the surface result measured at the maximum scanning resolution as the initial planar morphology state of the bulk amorphous alloy sample under test, and record the height value of a single pixel point of the surface morphology of the bulk amorphous alloy sample under test at this time. S122: True surface area of ​​the bulk amorphous alloy sample to be tested A * for: ； in A * represents the actual surface area of ​​the contact region of the amorphous alloy sample to be tested. A The surface area of ​​an ideal smooth plane, c These are AFM parameters, numerically equal to the side length of a single minimum representation dimension. For step function, when ,when .

5. The method for measuring the diffusion coefficient of bulk amorphous alloys under low-temperature conditions according to claim 1, characterized in that, In step S13, the stable surface area of ​​the bulk amorphous alloy sample to be tested is derived. A f It includes the following steps: S131: Measure the planar morphology of the amorphous alloy sample after one contact-separation and record the height value of a single pixel on the surface morphology of the amorphous alloy sample at this time. S132: Calculate the surface area of ​​the amorphous alloy after one contact-separation process. A * 1; S133: Calculate the surface area of ​​the amorphous alloy after 2, 5, 10, 20, and 50 contact-separation cycles. A * 2, A * 5, A * 10 , A * 20 , A * 50 ; Fitting after csc The true surface area of ​​the contact region of the bulk amorphous alloy sample after the first contact-separation cycle; ， in, This represents the true surface area of ​​the contact region of the amorphous alloy block sample after fitting. S134: Based on the above evolutionary rules, select the equilibrium segment. The stable surface area of ​​the amorphous alloy surface A f The corresponding number of contact-separation cycles is f .

6. The method for measuring the diffusion coefficient of bulk amorphous alloys under low-temperature conditions according to claim 1, characterized in that: In step 2, the critical load holding time The calculation process is as follows: Take two bulk amorphous alloy samples to be tested, arrange them vertically and face each other, and place them in a vacuum environment to reach the preset temperature value. T ; Control the upper part of the amorphous alloy sample to be tested to move downwards, passing through f After the second separation-contact cycle, adjust the external force. L Once the preset size is reached, maintain the loading state and sustain it. t Duration; The amorphous alloy sample to be tested is controlled to move upward at a constant strain rate. The force-displacement curve is recorded, and the magnitude of the external force causing the first-order discontinuity of the curve is determined based on the force-displacement curve. The separation force under this condition is recorded. F ; Multiple contact-separation cycle experiments were conducted to determine the separation force under the same temperature conditions. F With holding time t and external forces L Based on the relationship between them, it can be deduced that when a critical point is reached... And external forces L When = 0, the corresponding critical hold-up time .

7. An apparatus for measuring the diffusion coefficient of bulk amorphous alloys in a low-temperature environment according to any one of claims 1-6, characterized in that: include, A vacuum chamber that provides a vacuum environment for the device; An environmental chamber is located inside a vacuum chamber. The top of the environmental chamber is connected to the vacuum chamber, and the bottom is connected to a cooling medium channel to provide different ambient temperatures inside the environmental chamber according to the flow rate of the cooling medium. A laser gap detection device is located inside the environmental chamber and is set on both sides of the amorphous alloy sample to be tested. An adjustment mechanism, located within the environmental chamber, is used to control the loading or unloading of stress between the amorphous alloy samples to be tested, and to achieve stress changes by controlling the position of the samples.

8. The apparatus according to claim 7, characterized in that: The adjustment mechanism has a movable end. Two amorphous alloy samples to be tested are arranged facing each other vertically. The movable end is fixedly connected to the upper amorphous alloy sample to be tested. The adjustment mechanism controls the position of the upper amorphous alloy sample to be tested to achieve the loading or unloading of stress between the two amorphous alloy samples to be tested.

9. The apparatus according to claim 7, characterized in that: The adjustment mechanism is a mechanical testing machine; a temperature sensor is also installed inside the environmental chamber.

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