A TEM device for in-situ compression followed by in-situ tension

Abstract

The present invention discloses a TEM device for in-situ compression to in-situ tension, which is mainly characterized in that in a transmission electron microscope, the in-situ compression of a sample rod is converted into the in-situ tension of a sample. The present invention reduces the sample preparation workload of in-situ tensile samples in a transmission electron microscope, can simultaneously realize two functions of in-situ tension and in-situ compression by using an in-situ compression rod, and completely avoids the situation that the sample is bent due to the jitter of the sample rod during the sample stretching process. By recording the experimental process in real time, it provides direct evidence for exploring the strengthening mechanism and deformation mechanism of materials.

Description

Technical Field

[0001] The present invention relates to a transmission electron microscopy (TEM) device for in-situ compression to in-situ tension, belonging to the technical field of in-situ nano-mechanical testing of transmission electron microscopy (TEM). Background Art

[0002] The transmission electron microscopy (TEM) is a large-scale instrument for analyzing the structure and morphology of materials. Its theoretical resolution has reached 0.1 nm, making it one of the most powerful tools for analyzing material structures at the nanoscale. By in-situ observing the dynamic process of dislocation movement at the crack tip in materials and its high-resolution image through the transmission electron microscopy, the deformation and fracture mechanisms of materials are explored. With the development of material characterization techniques and the lightweight and miniaturization of key components in high-performance equipment, in-situ nano-mechanics of the transmission electron microscopy can directly observe the evolution process of stress-induced material deformation and fracture in real time at the microscale, analyze the movement of dislocations, and break through the previous barrier of only theoretically analyzing dislocations. However, in the in-situ tensile experiment of the transmission electron microscopy, the preparation of the in-situ tensile sample is crucial, and the quality of the sample directly determines the success or failure of the in-situ tensile experiment of the transmission electron microscopy.

[0003] The preparation of the in-situ tensile sample of the transmission electron microscopy is relatively difficult. Generally, multiple samples to be tested need to be prepared for the same treatment state. The diameter of the observation hole on the substrate of the in-situ tensile sample rod for fixing the sample is relatively small, making sample preparation difficult. When transferring the in-situ sample to the substrate on the in-situ tensile sample rod, the thickness of the sample is required to be about 80 nm. The glue connecting the sample and the substrate will spread to the entire sample through the action of surface tension, resulting in the inability to smoothly conduct the experiment. In addition, during the in-situ tensile process of the in-situ tensile sample of the transmission electron microscopy, the observation area may be a non-fracture area, and there will be inevitable jitter during the tensile process, causing the sample to bend directly.

[0004] In view of this, the present invention designs a TEM device for in-situ compression to in-situ tension, which can cleverly convert the pressure received by the sample rod into the tensile force on the sample, cleverly avoiding the occurrence of the above problems, and thus achieving the effect of in-situ stretching the sample. Summary of the Invention

[0005] In order to solve the above-mentioned existing problems, the present invention provides a TEM device for in-situ compression to in-situ tension.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] (1) Initially prepare the TEM device for in-situ compression to in-situ tension by using electrolytic polishing technology;

[0008] (2) Prepare samples with certain size specifications and thin the samples using an electrolytic twin-jet thinning instrument.

[0009] (3) Cut the in-situ compression to in-situ tension TEM device obtained in step (1) using a focused ion beam.

[0010] (4) Cut, transfer and fix the sample obtained in step (3) on the device in step (2) using a focused ion beam, and thin the sample.

[0011] (5) Load the sample obtained in step (4) into a transmission electron microscope for preliminary observation, and make the sample in a stressed state through preloading.

[0012] (6) Move the field of view to the center of the recorded image, control the stretching process by adjusting the compression rate of the in-situ compression to in-situ tension TEM device, and record the real-time process of in-situ stretching through video.

[0013] Further, in step (1), the size specifications of the prepared preliminary in-situ compression to in-situ tension TEM device are: length ≤ 5.5 mm, and the front end is flat.

[0014] Further, in step (1), the material used for the prepared needle-shaped sample rod is Ni 50 Ti 50 shape memory alloy material, with a diameter of 0.3 mm.

[0015] Further, in step (1), the electrolytic polishing solution uses a perchloric acid - glacial acetic acid solution.

[0016] Further, in step (2), before electrolytic twin-jet thinning, the sample is ground and polished to 60 - 80 μm, and the electrolytic twin-jet thinned sample is required to have small holes with weak light transmission under light conditions.

[0017] Further, in step (3), the specific steps for cutting the in-situ compression to in-situ tension TEM device using a focused ion beam are: fix the in-situ compression to in-situ tension TEM device on a 45° sample stage, tilt the sample stage by 52° in the ion beam system, deposit a Pt protective layer with a thickness of 200 - 400 nm on the part to be cut, cut the in-situ compression to in-situ tension TEM device using the ion beam, and adjust the beam current for fine trimming.

[0018] Further, in step (4), the specific steps of focused ion beam cutting, transferring, fixing, and thinning the sample are as follows: Fix the in-situ compression to in-situ tensile TEM device prepared in step (2) on the sample stage at 45° and the sample prepared in step (3) on the sample stage at 45°. Tilt the sample stage by 52° in the focused ion beam system. Deposit a layer of Pt on the surface of the sample to be cut. Use an ion beam of 30 nA to dig a groove above and below the area to be cut on the sample. Tilt the sample stage by 50° - 56°, and use an ion beam of 10 - 20 nA to refine the groove. Tilt the sample stage to -8° - 10°, weld the sample thin slice to the tungsten needle of the manipulator, and use the ion beam to cut off the sample and lift it out. Tilt the sample stage by 50° - 56°, weld the sample thin slice on the manipulator to the in-situ compression to in-situ tensile TEM device, use an ion beam of 3 nA to cut off the connection between the sample thin slice and the manipulator, and withdraw the manipulator. Return the sample stage to 45°, use an ion beam of 2 nA to make the sample thin slice into an I shape, and the width of the middle part of the sample thin slice is 2 - 4 μm. Return the sample stage to 0°, use an ion beam of 0.1 - 1 nA to thin the sample until it reaches 50 - 100 nm.

[0019] The above technical solution provided by the present invention has the following advantages compared with the prior art: The technical solution provided by the present invention reduces the repetition rate of sample preparation, converts the compression of the rod into the tension of the sample, and greatly avoids mistakes during the sample transfer process. When testing in a transmission electron microscope, the technical solution provided by the present invention completely avoids the sample bending caused by jitter during the stretching process. Description of the Drawings

[0020] Figure 1 For the size of the in-situ compression to in-situ tensile TEM device.

[0021] Figure 2 For the displacement change of the in-situ compression to in-situ tensile TEM device by finite element simulation.

[0022] Figure 3 For the tensile effect diagram of the titanium alloy material.

[0023] Among them, Figure 2 When the loading pressure is applied, the displacement of the TEM sample position is shown as tensile force, and the displacement is the tensile displacement. Detailed Embodiments

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0025] The specific implementation manners of the present invention will be further described below in conjunction with the technical solutions.

[0026] Example

[0027] The sample is a titanium alloy material, and the distance between the sample fixing positions of the TEM device for in-situ compression to in-situ tension is 3 μm. The TEM device for in-situ compression to in-situ tension uses Ni 50 Ti 50 shape memory alloy material. First, the Ni 50 Ti 50 shape memory alloy material with a diameter of 0.3 mm is extruded into a slightly flattened shape, and the Ni 50 Ti 50 with a diameter of 0.3 mm is electrolytically polished to a diameter of 20 - 30 μm (at the frontmost 1 mm) using an electrolytic polishing solution of perchloric acid - glacial acetic acid. The sample to be tested is ground and polished to 80 μm, and electrolytic twin-jet thinning is used to ensure that the sample has small holes with weak light transmission under light conditions.

[0028] The sample and the TEM device for in-situ compression to in-situ tension are fixed on a 45° sample stage, and a Pt protective layer with a thickness of 300 nm is deposited on the area to be cut on the TEM device for in-situ compression to in-situ tension. Two grooves with a length of 15 μm, a depth of 9 μm, and a thickness of 12 μm are cut on the sample surface using an ion beam of 30 nA, and the grooves are refined using an ion beam of 15 nA. The sample stage is tilted by -8°, the sample thin slice is welded to the manipulator, and the sample thin slice is cut off from the sample matrix part using an ion beam of 2 nA. The sample stage is tilted by 52°, the sample thin slice is moved to the sample fixing position of the TEM device for in-situ compression to in-situ tension, and the sample thin slice is welded to the sample fixing position of the TEM device for in-situ compression to in-situ tension using an ion beam of 50 pA. The connection between the sample thin slice and the manipulator is cut off using an ion beam of 3 nA, and the manipulator is withdrawn. The sample stage returns to 45°, and the sample thin slice is cut into an I shape using an ion beam of 2 nA, and the width of the middle part of the sample thin slice is 2 - 4 μm. The sample stage returns to 0°, and the sample is thinned to 80 nm using ion beams of 0.5 nA, 0.3 nA, and 0.1 nA.

[0029] The TEM device for in-situ compression to in-situ tension and the in-situ tensile sample as a whole above (see Figure 1 ) are transferred to a transmission electron microscope for preliminary observation. To ensure that the force received by the sample fixing part of the TEM device for in-situ compression to in-situ tension is a tensile force, we carried out a finite element simulation of the displacement change of the TEM device for in-situ compression to in-situ tension. When a pressure is applied, the displacement of the TEM sample position shows a tensile force, and the displacement is a tensile displacement.

[0030] Preload the sample to put it under stress; move the field of view to the center of the recording screen, control the stretching process by adjusting the compression rate of the TEM device that can switch from in-situ compression to in-situ stretching, and record the real-time process of in-situ stretching through video (see Figure 3 ). Through the analysis of the video, further study the fracture mechanism of the material.

Claims

1. An in-situ compression to in-situ tension TEM device for stretching and deforming a sample in a transmission electron microscope, Characterized in that: (1) The material selected is a commercial memory alloy material, Ti 50 Ni 50 , which has both high strength and high toughness, and has the advantage of being able to recover after local yielding, achieving the purpose of converting pressure into tension; The process uses electrolytic polishing technology to preliminarily prepare a TEM device for in-situ compression to in-situ tension; (2) Fabricate a sample with certain dimensional specifications and thin the sample using an electrolytic twin-jet thinning instrument; (3) Use a focused ion beam to cut the in-situ compression to in-situ tension TEM device obtained in step (1); (4) Use a focused ion beam to cut, transfer, and fix the sample obtained in step (3) onto the device in step (2), and thin the sample; In step (4), the specific steps of using the focused ion beam to cut, transfer, fix, and thin the sample are as follows: Fix the in-situ compression to in-situ tension TEM device prepared in step (2) on a 45° sample stage and the sample prepared in step (3) on a 45° sample stage. Tilt the sample stage 52° in the focused ion beam system, deposit a layer of Pt on the surface of the sample to be cut, and use a 30 nA ion beam to dig a groove above and below the area to be cut; Tilt the sample stage 50° - 56°, and use a 10 - 20 nA ion beam to refine the groove; Tilt the sample stage to -8° - 10°, weld the sample thin slice to the tungsten needle of the manipulator, and use an ion beam to cut off the sample and lift it out; Tilt the sample stage 50° - 56°, weld the sample thin slice on the manipulator to the in-situ compression to in-situ tension TEM device, use a 3 nA ion beam to cut off the connection between the sample thin slice and the manipulator, and withdraw the manipulator; Return the sample stage to 45°, use a 2 nA ion beam to cut the sample thin slice into an I shape, and the width of the middle part of the sample thin slice is 2 - 4 μm; Return the sample stage to 0°, use a 0.1 - 1 nA ion beam to thin the sample until it reaches 50 - 100 nm; (5) Load the sample obtained in step (4) into the transmission electron microscope for preliminary observation, and make the sample in a stressed state through preloading; (6) Move the field of view to the center of the recording screen, control the stretching process by adjusting the compression rate of the in-situ compression to in-situ tension TEM device, and record the real-time process of in-situ stretching through video.

2. An in-situ compression to in-situ tension TEM device according to claim 1, Characterized in that: In step (1), the dimensional specifications of the preliminary in-situ compression to in-situ tension TEM device prepared are: length ≤ 5.5 mm, and the front end is flat.

3. An in-situ compression to in-situ tension TEM device according to claim 1, Characterized in that: In step (1), the needle-shaped sample rod Ni is prepared. 50 Ti 50 The diameter of the shape memory alloy material is 0.3 mm.

4. An in-situ compression to in-situ tension TEM device according to claim 1, Characterized in that: In step (1), the electrolytic polishing solution uses a perchloric acid - glacial acetic acid solution.

5. An in-situ compression to in-situ tension TEM device according to claim 1, Characterized in that: In step (2), before electrolytic twin-jet thinning, polish the sample to 60 - 80 μm, and the electrolytic twin-jet thinned sample is required to have small holes with weak light transmission under light conditions.

6. An in-situ compression to in-situ tension TEM device according to claim 1, Characterized in that: In step (3), the specific steps for cutting the TEM device for in-situ compression to in-situ tension by focused ion beam are as follows: Fix the TEM device for in-situ compression to in-situ tension on a 45° sample stage, tilt the sample stage by 52° in the ion beam system, deposit a Pt protective layer with a thickness of 200 - 400 nm on the part to be cut, cut the TEM device for in-situ compression to in-situ tension using the ion beam, and adjust the beam current for fine machining.

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