Preparation method for EBSD analysis of polished surface of sheet sample

Abstract

The invention belongs to the technical field of metal micro-analysis, and particularly relates to a preparation method for EBSD analysis of a polished surface of a sheet sample. The method comprises the following steps: (1) sample interception: intercepting a sample, cleaning with alcohol, and blow-drying; (2) grinding the sample to be flat, namely grinding the section of the sample to be flat, performing low-speed grinding at the rotating speed of 70-100rad / min, sequentially polishing by using diamond suspension liquid with the average particle sizes of 10 mu m, 5 mu m and 1 mu m from 500 # to 2000 # abrasive paper, cleaning by using alcohol, and drying by blowing; and (3) fine polishing of the sample: performing ion polishing, setting voltage and time for the center of a polished surface at an ion beam focus point, and directly applying the fine-polished sample to EBSD analysis. Therefore, the problem that ion beam section polishing cannot be better carried out due to the fact that the upper end face and the lower end face of the machined surface of the sample are not parallel and the thickness of the polished surface is below 1mm is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of metal micro-analysis, and in particular relates to a preparation method for EBSD analysis of a polished surface (with a thickness of less than 1 mm) of a thin slice sample. Background Art

[0002] EBSD (Electron Backscattered Diffraction) technology is the analysis of diffraction Kikuchi bands formed by electron beam irradiation on the inclined sample surface, so as to obtain and determine the sample crystal structure, crystal orientation, phase distribution and identification, grain boundary, calibration rate analysis and other information. EBSD requires that the sample surface has no stress layer, no oxide layer, no continuous corrosion pits, and the surface is flat, highly smooth and pollution-free.

[0003] At present, mechanical polishing, chemical polishing, and electrolytic polishing are used to prepare conventional EBSD samples. The analyzed samples must be flat and stress-free. However, for the preparation of coated material samples, the commonly used sample preparation methods cannot meet the requirements of the preparation of such materials for the observation interface. Ion beam cross-sectional polishing has the advantages of no residual shear stress, no abrasive contamination, no scratches, and little sample damage. However, since the ion beam cross-sectional polishing sample requires that the upper and lower end faces of the sample to be processed are flat and parallel, and the thickness of the polished surface is greater than 3mm. For some small samples, the sample can be inlaid and then ion beam polished. If the sample is inlaid with an inlay, ion beam polishing cannot accurately remove the coating first, and secondly, the inlay needs to be removed and placed on the EBSD sample stage for observation and photography. The sample surface may be contaminated during the removal of the inlay, so the processing of the above samples is subject to some limitations. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation method for EBSD analysis of a thin slice sample with a polished surface thickness of less than 1 mm, which solves the problem that ion beam cross-section polishing cannot be better performed due to the upper and lower end faces of the sample being processed being not parallel and the polished surface thickness being less than 1 mm.

[0005] The technical solution of the present invention is:

[0006] A preparation method for EBSD analysis of the polished surface of a thin section sample, the specific steps and parameters are as follows:

[0007] (1) Sample collection: Samples are collected, cleaned with alcohol, and blown dry;

[0008] (2) Grinding of samples: Grind the cross section of the sample flat, use a slow grinding speed of 70-100 rad / min, and polish with diamond suspensions with average particle sizes of 10 μm, 5 μm, and 1 μm from 500# to 2000# sandpaper, then clean with alcohol and blow dry;

[0009] (3) Fine polishing of samples: Using ion polishing, the center of the polished surface is at the ion beam focus point, and the voltage and time are set. The finely polished samples are directly used for EBSD analysis;

[0010] (4) EBSD signal acquisition and analysis: The finely polished sample was fixed on the pre-tilted sample stage for EBSD experiment with conductive tape, and the sample was placed in the sample chamber of the field emission scanning electron microscope to obtain a clear image; the analysis area was selected at the edge of the cross section, and the step size was set to no more than 1 / 10 of the average grain size. The EBSD full-view field scan was performed at a magnification of 1000 to 3000 times, and the scan data was subjected to microscopic strain analysis using the Strain Contouring module in the AZtecCrystal program.

[0011] In the preparation method for EBSD analysis of the polished surface of a thin section sample, in step 1, the sample size is cut into: length <8mm, thickness <8mm, so as to be used for EBSD analysis.

[0012] In the preparation method for EBSD analysis of the polished surface of a thin-section sample, in step 3, the sample is placed in a groove on a sample stage of an ion polisher, the sample stage is fixed by a positioning knob, a baffle is provided on the top of the sample, and the ion beam is located directly above the sample.

[0013] In the preparation method for EBSD analysis of the polished surface of a thin-section sample, in step 3, the positioning knob is adjusted to make the polished surface close to the baffle and the polishing thickness is adjusted to 10 to 60 μm, so that the center of the sample is at the focus point of the ion beam.

[0014] In the preparation method for EBSD analysis of the polished surface of a thin slice sample, in step 3, the parameters of ion polishing are: ion gun acceleration voltage 6kV~8kV, polishing time 6h~8h, then adjusting the acceleration voltage to 2kV~3kV and polishing time 0.5~1h.

[0015] In the preparation method for EBSD analysis of the polished surface of a thin slice sample, in step 3, a stress-free polishing area with a length of ≤4 mm and a width of ≤1 mm is obtained after fine polishing.

[0016] The design idea of ​​the present invention is:

[0017] Since the traditional EBSD sample preparation method cannot meet the problem that the upper and lower end faces of the sample processing surface are not parallel and the thickness of the polished surface is less than 1 mm, which leads to the inability to better perform ion beam cross-section polishing, the present invention solves the above problem by changing the position between the sample and the sample stage. It has the advantages of simple preparation method, strong operability and high sample reproducibility, and can clearly characterize the interface area of ​​hundreds of microns.

[0018] The advantages and beneficial effects of the present invention are:

[0019] 1. The present invention solves the problem that ion beam cross-section polishing cannot be performed better due to the upper and lower end faces of the sample being processed being not parallel and the thickness of the processed surface being less than 1 mm. A polished cross-section without residual stress can be obtained, and EBSD signals can be continuously collected in the area within 1 mm of the interface between the coating and the substrate.

[0020] 2. The present invention has the advantages of simple preparation method, strong operability and high sample reproducibility, and can clearly characterize the interface area of ​​several hundred microns. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of placing the sample on the sample stage of the ion polisher. In the figure, 1 is the ion beam, 2 is the baffle, 3 is the sample, 4 is the sample stage, and 5 is the positioning knob.

[0022] Figure 2 This is the morphology of the coating sample after fine polishing.

[0023] Figure 3 The left picture is the surface morphology picture and the right picture is the EBSD pattern quality distribution picture of the cross section of the dotted area in the left picture. DETAILED DESCRIPTION

[0024] In the specific implementation process, the equipment used includes a field emission scanning electron microscope ZEISS Gemini SEM 460, a Leica triple ion beam cutter EM TIC 3X, an Oxford Instruments Symmetry S2 EBSD accessory, and Aztec data acquisition software and AZtecCrystal data processing software.

[0025] like Figure 1 As shown, the sample 3 is placed in a groove on the sample stage 4 of the ion polisher. The sample stage 4 is fixed by a positioning knob 5. A baffle 2 is provided on the top of the sample 3. The ion beam 1 is located directly above the sample 3.

[0026] Below, the present invention is further described in detail by examples.

[0027] Example 1

[0028] In this embodiment, a preparation method for EBSD analysis of a cross-section sample of a coating material with a processed surface thickness of less than 1 mm is provided, and the specific steps and parameters are as follows:

[0029] (1) Sample cutting: Cut a sample with a cross section of 5 mm long and 5 mm thick, clean it with alcohol, and blow dry it;

[0030] (2) Grinding of samples: Grind the cross section of the sample flat, use a slow grinding speed of 70-100 rad / min, from 500# to 2000# sandpaper (500#→600#→800#→1000#→1200#→1500#→2000#), and then polish with diamond suspensions with average particle sizes of 10μm, 5μm and 1μm in turn, clean with alcohol, and blow dry;

[0031] (3) Fine polishing of samples: Figure 1 As shown, adjust the positioning knob 5, place the polished surface of the sample 3 close to the baffle 2 and adjust the polishing thickness to 45 μm, and place the center of the polished surface at the focus point of the ion beam 1. Use ion polishing and set the polishing parameters: ion gun acceleration voltage 7 kV, polishing time 6 h, adjust the acceleration voltage to 2 kV, polishing time 0.5 h, and obtain a stress-free polishing area of ​​4 mm in length and 1 mm in width after fine polishing. The finely polished sample is directly used for EBSD analysis;

[0032] like Figure 2 As shown in the figure, the morphology of the coating sample after fine polishing shows that the sample can obtain a polished section with a length of 4 mm and a width of 1 mm without residual stress. Its surface has no stress layer, no oxide layer, no continuous corrosion pits, and the surface is flat, highly smooth and pollution-free.

[0033] (4) EBSD signal acquisition and analysis: The polished coating cross-section sample was fixed on the pre-tilted sample stage for EBSD experiment with conductive tape, and the finely polished sample was placed in the sample chamber of the field emission scanning electron microscope to obtain a clear image; the analysis area was selected at the edge of the cross section, and the step size was set to 1 / 12 of the average grain size. The EBSD full-view field scan was performed at a magnification of 2000 times, and the microscopic strain analysis of the scan data was performed using the Strain Contouring module in the AZtecCrystal program.

[0034] like Figure 3 As shown in the figure, the surface morphology of the coating sample after fine polishing and the EBSD pattern quality distribution diagram of the cross section show that the interface between the coating and the substrate is clear after fine polishing. The microstructure on the interface is clearly visible in the EBSD diagram, and the resolution rate can reach 90%, which can meet the analysis requirements.

Claims

1. A preparation method for EBSD analysis of the polished surface of a thin section sample, characterized in that: The specific steps and parameters are as follows: (1) Sample collection: Samples are collected, cleaned with alcohol, and blown dry; (2) Grinding of samples: Grind the cross section of the sample flat, use a slow grinding speed of 70-100 rad / min, and polish with diamond suspensions with average particle sizes of 10 μm, 5 μm, and 1 μm from 500# to 2000# sandpaper, then clean with alcohol and blow dry; (3) Fine polishing of samples: Using ion polishing, the center of the polished surface is at the ion beam focus point, and the voltage and time are set. The finely polished samples are directly used for EBSD analysis; (4) EBSD signal acquisition and analysis: The finely polished sample was fixed on the pre-tilted sample stage for EBSD experiment with conductive tape, and the sample was placed in the sample chamber of the field emission scanning electron microscope to obtain a clear image; the analysis area was selected at the edge of the cross section, and the step size was set to no more than 1 / 10 of the average grain size. The EBSD full-view field scan was performed at a magnification of 1000 to 3000 times, and the scan data was subjected to microscopic strain analysis using the Strain Contouring module in the AZtecCrystal program.

2. The method for preparing a polished surface of a thin section sample for EBSD analysis according to claim 1, characterized in that: In step 1, the sample size is: length <8mm, thickness <8mm, so as to be used for EBSD analysis.

3. The method for preparing a polished surface of a thin section sample for EBSD analysis according to claim 1, characterized in that: In step 3, the sample is placed in a groove on the sample stage of the ion polisher. The sample stage is fixed by a positioning knob. A baffle is provided on the top of the sample, and the ion beam is located directly above the sample.

4. The method for preparing a polished surface of a thin section sample for EBSD analysis according to claim 3, characterized in that: In step 3, the positioning knob is adjusted to bring the polished surface close to the baffle and the polishing thickness is adjusted to 10 to 60 μm, so that the center of the sample is at the focus point of the ion beam.

5. The method for preparing a polished surface of a thin section sample for EBSD analysis according to claim 1, characterized in that: In step 3, the parameters of ion polishing are: ion gun acceleration voltage 6 kV ~ 8 kV, polishing time 6h ~ 8h, then adjust the acceleration voltage to 2 kV ~ 3 kV, polishing time 0.5 ~ 1h.

6. The method for preparing a polished surface of a thin section sample for EBSD analysis according to claim 1, characterized in that: In step 3, a stress-free polishing area with a length of ≤4 mm and a width of ≤1 mm is obtained after fine polishing.

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