Preparation method of neodymium iron boron electron back scattering diffraction sample

Abstract

The invention discloses a preparation method of a neodymium-iron-boron electron back scattering diffraction sample. The preparation method comprises the following steps: metallographic phase mounting: mixing a neodymium-iron-boron sample with conductive resin powder, and carrying out hot press molding; mechanical grinding: grinding step by step by adopting 200 #, 400 # and 800 # abrasive paper, wherein the total time is less than or equal to 9 minutes; mechanical polishing is conducted, specifically, a 1.5-micron aluminum oxide polishing agent is used in cooperation with porous nylon cloth for polishing for 5 minutes; mechanical and chemical polishing: polishing lint for 30-120 minutes by adopting a polishing solution containing 50nm silica sol, a pH regulator and an antioxidant; washing with absolute ethyl alcohol and blow-drying; by optimizing the formula and process parameters of the polishing solution, the sample preparation time is shortened to be less than or equal to 120 minutes, the surface roughness Ra is less than or equal to 10nm, and the Kikuchi pattern signal-to-noise ratio is greater than or equal to 6: 1; the low-cost aluminum oxide and silica sol polishing agent is adopted, so that the cost of consumables is reduced; the antioxidant effectively inhibits neodymium iron boron oxidation, and the pH regulator improves the stability of the polishing solution; the method has the characteristics of high efficiency, low cost and excellent quality, and can meet the high-precision EBSD analysis requirement.

Description

Technical Field

[0001] The invention relates to the technical field of material microanalysis, and in particular to a method for preparing a neodymium iron boron electron backscatter diffraction sample. Background Art

[0002] NdFeB magnets are widely used in new energy vehicles, wind power generation, medical imaging and other fields due to their excellent magnetic properties. EBSD technology is a key means to analyze its microscopic grain orientation, phase distribution and grain boundary characteristics. At the same time, due to the extremely strong magnetic anisotropy of NdFeB materials, the crystal orientation of the material is of decisive significance to the performance of the final magnet. Therefore, it is necessary to use EBSD technology to analyze the orientation of NdFeB magnets. However, NdFeB magnets are susceptible to oxidation and corrosion, and have high hardness and high brittleness, resulting in the following challenges for EBSD sample preparation: Limitations of existing sample preparation methods: Argon ion polishing: The equipment purchase cost is high (more than 1 million yuan per unit), the function is single, the maintenance is complex, and the high-energy ion beam is easy to introduce surface amorphization, resulting in a decrease in the signal-to-noise ratio of the Kikuchi pattern (see attached Figure 2 (B));

[0003] Electrolytic polishing: The process parameters (voltage, electrolyte concentration) are difficult to control precisely, which can easily cause uneven corrosion on the sample surface, preferential dissolution of the Nd-rich phase, and affect grain boundary analysis;

[0004] Vibration polishing: It needs to run continuously for 8 to 12 hours, the equipment cost is high (over 500,000 yuan), and long-term mechanical vibration may cause damage to the edge of the sample.

[0005] Disadvantages of traditional metallographic sample preparation: The inevitable introduction of grinding stress in traditional metallographic sample preparation schemes makes EBSD testing impossible. Although traditional metal materials can effectively remove stress layers through electrolytic polishing, for NdFeB materials, their high activity leads to excessive corrosion, which limits the application of electrolytic polishing. However, the existing technology CN113514485A discloses a method for preparing NdFeB electron backscatter diffraction analysis samples, which not only relies on multi-grade sandpaper (No. 120 to 2500) for step-by-step grinding, which takes up to 4 to 6 hours, but also requires vibration polishing to eliminate surface stress.

[0006] Therefore, in response to the above problems, the present invention provides a method for preparing NdFeB electron backscatter diffraction samples. By optimizing the grinding and polishing processes and introducing a customized polishing liquid formula, a NdFeB EBSD sample preparation method with high efficiency, low cost and universality is developed, which significantly shortens the sample preparation cycle, reduces equipment dependence and consumables costs, and is particularly suitable for conventional laboratory environments without dedicated polishing equipment. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for preparing NdFeB electron backscatter diffraction samples, a method for rapidly preparing NdFeB EBSD samples, which shortens the sample preparation cycle and reduces equipment dependence and consumables costs by simplifying the sample preparation process, optimizing the polishing liquid formula and abandoning special equipment.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A method for preparing a NdFeB electron backscatter diffraction sample comprises the following steps:

[0010] (1) Metallographic mounting: Nd2Fe 14 B) The sample and conductive resin powder are mixed at a weight ratio of 20% to 40%, and the mixture is placed in a mounting machine and hot pressed to form a mounting block with a height of 1 to 1.5 cm;

[0011] (2) Mechanical grinding: Use 200, 400, and 800 sandpaper in sequence, grinding for 1 to 3 minutes per level, with a rotation speed of 200 to 400 rpm, and the total grinding time is ≤ 9 minutes;

[0012] (3) Mechanical polishing: Use 1.5 ± 0.2 μm alumina polishing agent with porous nylon cloth and polish at a speed of 150-600 rpm for 3-5 minutes;

[0013] (4) Mechanical chemical polishing: polishing is performed using a mechanical chemical polishing solution comprising: a 50 nm silica sol suspension, a pH regulator, and an antioxidant, with flannel as a carrier, polishing at a speed of 100 to 200 rpm for 30 to 120 minutes to remove the surface stress layer through mechanical-chemical synergy;

[0014] (5) Sample cleaning: rinse with anhydrous ethanol and blow dry to obtain a NdFeB electron backscatter diffraction (EBSD) sample with a surface roughness of Ra ≤ 10 nm.

[0015] Preferably, in step (1), the conductive resin powder is a carbon-based thermosetting resin with a shrinkage rate of <5%; the pressure of the hot pressing molding is 1-3 MPa, the temperature is 120-180° C., and the heat preservation is 2-5 minutes.

[0016] Preferably, in step (3), the porosity of the porous nylon cloth is 30% to 50%.

[0017] Preferably, in step (4), the concentration of the silica sol suspension is 5% to 10wt%; the pH adjuster is a strong alkaline solution or can produce a strong alkaline solution after hydrolysis, and the pH adjuster adjusts the pH value to 8 to 10; further preferably, the pH adjuster includes but is not limited to NaOH, which enhances the dispersibility of SiO2.

[0018] Preferably, the antioxidant is 0.1% to 0.5% benzotriazole (BTA), which is used to inhibit the oxidative corrosion of the Nd-rich phase at the grain boundary of NdFeB.

[0019] Preferably, in step (1), the NdFeB sample is in block or flake form, or in powder form with a particle size of 0.5 to 500 microns, to ensure uniform conductivity of the mounted sample.

[0020] Preferably, the polishing endpoint is monitored in real time by a laser confocal microscope, and polishing is terminated when the surface roughness Ra is less than or equal to 10 nm.

[0021] Preferably, the whole sample preparation time of the NdFeB electron backscatter diffraction sample preparation method is ≤60 minutes.

[0022] Preferably, in step (4), during the preparation of the mechanical chemical polishing solution, the silica sol suspension and the antioxidant are mixed at room temperature and ultrasonically dispersed for 1 to 15 minutes.

[0023] Preferably, in the mechanical polishing step, the synergistic effect of the aluminum oxide polishing agent and the porous nylon cloth enables the surface scratch elimination rate to be ≥95%.

[0024] Preferably, the cost of the aluminum oxide polishing agent is 20% of that of the diamond polishing liquid.

[0025] Preferably, in the mechanochemical polishing step, the silica sol suspension forms a passivation film on the sample surface through a mechanical-chemical synergistic effect, thereby inhibiting oxidation and improving the contrast of the Kikuchi pattern.

[0026] Preferably, in the metallographic mounting step, the conductivity uniformity error of the mounting block after hot pressing is ≤5%.

[0027] Preferably, the method is applicable to EBSD sample preparation of sintered NdFeB magnets, hot pressed NdFeB magnets and bonded NdFeB magnets.

[0028] The present application also claims protection for a NdFeB electron backscatter diffraction sample, which is prepared using the above-mentioned method for preparing the NdFeB electron backscatter diffraction sample. The NdFeB electron backscatter diffraction sample has no ion damage, amorphization or stress defects on its surface, a Kikuchi pattern signal-to-noise ratio of ≥6:1, and a grain boundary resolution of 0.1 micron, making it suitable for high-precision crystal orientation analysis.

[0029] Preferably, the sample can cover an area of ​​≥200 μm×150 μm in EBSD analysis, and the grain orientation distribution error is ≤2°.

[0030] Preferably, in the mechanical polishing step (3), a 1.5±0.2 diamond suspension can be used in combination with porous nylon cloth, and polishing can be performed at a speed of 150-600 rpm for 5 minutes to reduce deep stress;

[0031] Preferably, in the mechanical chemical polishing of the above step (4), a mechanical chemical polishing liquid is used for polishing, and the mechanical chemical polishing liquid may also include a 50nm silica sol suspension (the concentration of the silica sol suspension is 5% to 10wt%), an antioxidant (0.1% to 0.5% benzotriazole (BTA)), and a polyvinyl pyrrolidone dispersant 0.1%, pH = 9.5); with a flocked polishing cloth, the mechanical polishing pressure is set to 0.1N / mm 2 , polish continuously for 30-120 minutes (rotation speed 120rpm), and eliminate subsurface damage through the synergistic effect of mechanical grinding and chemical passivation.

[0032] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0033] 1. The present invention significantly improves sample preparation efficiency: Traditional EBSD sample preparation usually takes ≥12 hours (such as electrolytic polishing and argon ion polishing). However, by optimizing the mechanical grinding, mechanical polishing, and mechanochemical polishing processes, the present invention reduces the sample preparation time to ≤120 minutes, increasing efficiency by more than 5 times. The mechanochemical polishing time is shortened to 30-120 minutes, significantly reducing the operation time compared to traditional vibration polishing (several hours) or electrolytic polishing (which requires repeated parameter adjustment).

[0034] 2. The present invention significantly reduces costs by using 1.5-micron alumina polishing agent (costing only 20% of diamond polishing fluid) and silica sol-based polishing fluid (costing 30% of traditional consumables), significantly reducing consumable costs. It does not require expensive argon ion polishers or vibration polishers, but only requires conventional metallographic grinding and polishing equipment, lowering the equipment investment threshold.

[0035] 3. The sample quality of the present invention is optimized, and the Kikuchi pattern has high clarity. Through the synergistic effect of pH adjustment (pH 8-10) and antioxidant (BTA), the oxidation of NdFeB is effectively inhibited, the surface amorphization is reduced, and the signal-to-noise ratio of the Kikuchi pattern is improved (≥6:1). Mechanical chemical polishing removes the stress layer and forms a passivation film, making the sample surface roughness Ra ≤ 10nm, meeting the requirements of high-resolution EBSD analysis.

[0036] 4. The present invention has a wide range of applications and is easy to operate. It is suitable for block, flake and powder (0.5-500 micron) NdFeB samples. Conductive resin mounting ensures the uniformity of powder samples. The polishing endpoint can be monitored in real time (laser confocal microscope detection Ra ≤ 10nm) to avoid over-polishing or under-polishing. In addition, the present invention only requires a conventional metallographic polishing machine, without the need for an argon ion polisher or a vibration polisher.

[0037] 5. The process of the present invention is stable and has good repeatability. The parameters of each step (temperature, pressure, speed, time) are precisely controllable, ensuring the consistency of sample preparation in different batches. Compared with electrolytic polishing (which is easily affected by electrolyte composition and voltage fluctuations), this method is less affected by environmental factors and has a higher yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific embodiments or the description of the prior art. Obviously, some of the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be made based on these drawings without paying any creative work.

[0039] Figure 1 This is a flow chart of the sample preparation process of Example 1 of the present invention;

[0040] Figure 2 The figures are Kikuchi pattern diagrams of samples prepared in Example 1 and Comparative Example 1 of the present invention, wherein (A) is Example 1 and (B) is Comparative Example 1;

[0041] Figure 3 EBSD grain contrast and orientation distribution diagram of the sample of Example 1 of the present invention;

[0042] Figure 4 EBSD grain contrast and orientation distribution diagram of the sample of Example 2 of the present invention;

[0043] Figure 5 This is the EBSD grain contrast and orientation distribution diagram of the sample in Example 3 of the present invention. DETAILED DESCRIPTION

[0044] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, a specific implementation scheme is now described in detail.

[0045] The present invention is further described below with reference to the following examples, but the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific applications. The implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention may be combined with each other as long as they do not conflict with each other.

[0046] Example 1

[0047] See attached Figure 1 , Attachment Figure 2 and attached Figure 3 This embodiment provides a method for preparing a NdFeB electron backscatter diffraction sample, comprising the following steps:

[0048] (1) Metallographic mounting: Take a sintered Nd2Fe 14 The B block was mixed with carbon-based conductive resin powder (weight ratio 1:3) and placed in a mounting machine for hot pressing (hot pressing pressure 2 MPa, temperature 150 ° C, holding temperature for 3 minutes) to form a mounting block with a height of 1.5 cm;

[0049] (2) Mechanical grinding: Use 200, 400, and 800 sandpaper in sequence, grinding for 2 minutes per level, at a speed of 300 rpm, and the total grinding time is ≤ 9 minutes;

[0050] (3) Mechanical polishing: Use 1.5 μm alumina polishing agent with porous nylon cloth (the porosity of the porous nylon cloth is 40%) and polish at a speed of 200 rpm for 5 minutes;

[0051] (4) Mechanical chemical polishing: Polishing was performed using a mechanical chemical polishing solution comprising: a 50 nm silica sol suspension (the concentration of the silica sol suspension was 8 wt%), a pH regulator NaOH, and 0.3% benzotriazole (BTA), wherein the pH value was adjusted to 9.5 by the pH regulator (during the preparation of the mechanical chemical polishing solution, the silica sol suspension and the antioxidant were mixed at room temperature and ultrasonically dispersed for 10 minutes). The surface was polished at a speed of 150 rpm for 60 minutes using a flannel as a carrier to remove the surface stress layer and form a passivation film through mechanical-chemical synergy;

[0052] (5) Sample cleaning: rinse with anhydrous ethanol and blow dry to obtain a NdFeB electron backscatter diffraction (EBSD) sample with a surface roughness of Ra ≤ 10 nm. EBSD detection shows a clear Kikuchi pattern, see attached Figure 2 (A); Attachment Figure 3 The sample of this embodiment has a contrast and orientation distribution diagram, wherein (A) has a contrast, (B) has a <001> Orientation distribution (non-Nd2Fe 14 Phase B is not calibrated).

[0053] Example 2

[0054] See attached Figure 4 This embodiment provides a method for preparing a NdFeB electron backscatter diffraction sample, comprising the following steps:

[0055] (1) Metallographic mounting: Take a sintered Nd2Fe 14 The B block was mixed with carbon-based conductive resin powder at a weight ratio of 30%, and placed in a mounting machine for hot pressing (the hot pressing pressure was 2 MPa, the temperature was 150°C, and the temperature was kept at this temperature for 3 minutes) to form a mounting block with a height of 1.5 cm;

[0056] (2) Mechanical grinding: Use 200, 400, and 800 sandpaper in sequence, grinding for 2 minutes per level, at a speed of 300 rpm, and the total grinding time is ≤ 9 minutes;

[0057] (3) Mechanical polishing: Use 1.5 μm alumina polishing agent with porous nylon cloth (the porosity of the porous nylon cloth is 40%) and polish at a speed of 200 rpm for 3 minutes;

[0058] (4) Mechanical chemical polishing: Polishing was performed using a mechanical chemical polishing solution comprising: a 50 nm silica sol suspension (the concentration of the silica sol suspension was 8 wt%), a pH regulator NaOH, and 0.3% benzotriazole (BTA), wherein the pH value was adjusted to 9.5 by the pH regulator (during the preparation of the mechanical chemical polishing solution, the silica sol suspension and the antioxidant were mixed at room temperature and ultrasonically dispersed for 10 minutes). The surface was polished at a speed of 150 rpm for 60 minutes using a flannel as a carrier to remove the surface stress layer by mechanical-chemical synergy.

[0059] (5) Sample cleaning: After rinsing with anhydrous ethanol and drying, a NdFeB electron backscatter diffraction (EBSD) sample with a surface roughness of Ra ≤ 10 nm was obtained. The final sample Kikuchi pattern had a signal-to-noise ratio of 6.5:1, and the cost of a single sample preparation was only 40 yuan (the traditional method required 130 yuan). Figure 4 The contrast and orientation distribution diagrams of this embodiment are shown in Figure (A) with contrast and Figure (B) with orientation. <001> Orientation distribution (non-Nd2Fe 14 Phase B is not calibrated).

[0060] Example 3

[0061] See attached Figure 5 This embodiment provides a method for preparing a NdFeB electron backscatter diffraction sample, comprising the following steps:

[0062] (1) Metallographic mounting: Take a sintered Nd2Fe 14 The B block was mixed with carbon-based conductive resin powder (weight ratio 1:3) and placed in a mounting machine for hot pressing (hot pressing pressure 2 MPa, temperature 150 ° C, holding temperature for 3 minutes) to form a mounting block with a height of 1.5 cm;

[0063] (2) Mechanical grinding: Use 200, 400, and 800 sandpaper in sequence, grinding for 2 minutes per level, at a speed of 300 rpm, and the total grinding time is ≤ 9 minutes;

[0064] (3) Mechanical polishing: Use 1.5 diamond suspension with porous nylon cloth (the porosity of the porous nylon cloth is 40%) and polish at a speed of 200 rpm for 5 minutes;

[0065] (4) Mechanical chemical polishing: Polishing was performed using a mechanical chemical polishing solution comprising: a 50 nm silica sol suspension (the concentration of the silica sol suspension was 8 wt%), 0.3% benzotriazole (BTA), 0.1% polyvinyl pyrrolidone dispersant, pH = 9.5 (during the preparation of the mechanical chemical polishing solution, the silica sol suspension and the antioxidant were mixed at room temperature and ultrasonically dispersed for 10 minutes), with a flocked polishing cloth, and a mechanical polishing pressure of 0.1 N / mm was set. 2 , continuous polishing for 30 minutes (rotation speed 120 rpm), eliminating subsurface damage through the synergistic effect of mechanical grinding and chemical passivation;

[0066] (5) Sample cleaning: rinse with anhydrous ethanol and blow dry to obtain NdFeB electron backscatter diffraction (EBSD) samples with surface roughness Ra≤10nm. EBSD detection shows that the band contrast and orientation contrast fully meet the detection requirements of NdFeB magnets (see Appendix Figure 5 ) Figure 5 The contrast and orientation distribution diagrams of this embodiment are shown in Figure (A) with contrast and Figure (B) with orientation. <001> Orientation distribution (non-Nd2Fe 14 Phase B is not calibrated).

[0067] Comparative Example 1

[0068] This comparative example is a traditional argon ion polishing method. The sample was prepared by argon ion polishing. The whole process took 12 hours. The signal-to-noise ratio of the Kikuchi pattern was 3.8:1, and there was an amorphous area on the surface. Figure 2 (B).

[0069] As demonstrated by the aforementioned examples and comparative examples, this method has been applied in the laboratory of a magnetic materials company, preparing 500 samples, all of which met the requirements of EBSD analysis. Compared to traditional processes, this method has saved over 3 million yuan in annual equipment procurement costs and increased sample preparation efficiency by 85%.

[0070] In summary, the present invention significantly improves the sample preparation efficiency: traditional EBSD sample preparation usually takes ≥12 hours (such as electrolytic polishing, argon ion polishing, etc.), while the present invention optimizes the mechanical grinding, mechanical polishing and mechanical chemical polishing processes, and the whole sample preparation time is ≤120 minutes, which improves the efficiency by more than 5 times; the mechanical chemical polishing time is shortened to 30-120 minutes, which greatly reduces the operation time compared with traditional vibration polishing (several hours) or electrolytic polishing (requires repeated adjustment of parameters); the present invention significantly reduces the cost, and adopts 1.5 micron alumina polishing agent (the cost is only 20% of diamond polishing liquid) and silica sol-based polishing liquid (the cost is 30% of traditional consumables), which greatly reduces the cost of consumables; there is no need to rely on expensive argon ion polishing instruments or vibration polishing machines, only conventional metallographic grinding and polishing equipment is required, which reduces the equipment investment threshold; the sample quality of the present invention is optimized, the clarity of the Kikuchi pattern is high, and the pH adjustment (pH8-10) and antioxidants ( The synergistic effect of BTA) effectively inhibits NdFeB oxidation, reduces surface amorphization, and improves the Kikuchi pattern signal-to-noise ratio (≥6:1); mechanical chemical polishing removes the stress layer and makes the sample surface roughness Ra≤10nm, meeting the requirements of high-resolution EBSD analysis; the present invention has a wide range of applications and is easy to operate. It is suitable for block, flake and powder (0.5-500 microns) NdFeB samples, and conductive resin mounting ensures the uniformity of powder samples; the polishing endpoint can be monitored in real time (step profiler detects Ra≤10nm) to avoid over-polishing or under-polishing; and the present invention only requires a conventional metallographic grinder and polisher, without the need for an argon ion polisher or a vibration polisher; the process of the present invention is stable and repeatable, and the parameters of each step (temperature, pressure, speed, time) are precisely controllable to ensure the consistency of sample preparation in different batches; compared with electrolytic polishing (which is easily affected by electrolyte composition and voltage fluctuations), this method is less affected by environmental factors and has a higher yield.

[0071] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a NdFeB electron backscatter diffraction sample, characterized in that: The steps include: (1) Metallographic mounting: Mix the NdFeB sample with conductive resin powder in a weight ratio of 20% to 40%, place it in a mounting machine and hot press it to form a mounting block with a height of 1 to 1.5 cm; (2) Mechanical grinding: Use 200, 400, and 800 sandpaper in sequence, grinding for 1 to 3 minutes per level, with a rotation speed of 200 to 400 rpm, and the total grinding time is ≤ 9 minutes; (3) Mechanical polishing: Use 1.5 ± 0.2 μm alumina polishing agent with porous nylon cloth and polish at a speed of 150-600 rpm for 3-5 minutes; (4) Mechanical chemical polishing: polishing is performed using a mechanical chemical polishing solution comprising: a 50 nm silica sol suspension, a pH regulator, and an antioxidant, with flannel as a carrier, polishing at a speed of 100 to 200 rpm for 30 to 120 minutes to remove the surface stress layer through mechanical-chemical synergy; (5) Sample cleaning: rinse with anhydrous ethanol and blow dry to obtain a NdFeB electron backscattered diffraction sample with a surface roughness of Ra ≤ 10 nm.

2. The method for preparing a NdFeB electron backscatter diffraction sample according to claim 1, wherein: In step (1), the conductive resin powder is a carbon-based thermosetting resin with a shrinkage rate of <5%; the pressure of the hot pressing molding is 1-3 MPa, the temperature is 120-180° C., and the heat preservation is 2-5 minutes.

3. The method for preparing a NdFeB electron backscatter diffraction sample according to claim 1, wherein: In step (3), the porosity of the porous nylon cloth is 30% to 50%.

4. The method for preparing a NdFeB electron backscatter diffraction sample according to claim 1, wherein: In step (4), the concentration of the silica sol suspension is 5% to 10 wt%; the pH regulator is a strong alkaline solution or can produce a strong alkaline solution after hydrolysis, and the pH regulator adjusts the pH value to 8 to 10.

5. The method for preparing a NdFeB electron backscatter diffraction sample according to claim 1, wherein: The antioxidant is 0.1% to 0.5% benzotriazole.

6. The method for preparing a NdFeB electron backscatter diffraction sample according to claim 1, wherein: In step (1), the NdFeB sample is in block or flake form, or in powder form with a particle size of 0.5 to 500 microns.

7. The method for preparing a NdFeB electron backscatter diffraction sample according to claim 1, wherein: The polishing endpoint is monitored in real time by a laser confocal microscope, and polishing is terminated when the surface roughness Ra is less than or equal to 10 nm.

8. The method for preparing a NdFeB electron backscatter diffraction sample according to claim 1, wherein: The whole sample preparation time of the NdFeB electron backscatter diffraction sample preparation method is ≤120 minutes.

9. The method for preparing a NdFeB electron backscatter diffraction sample according to claim 1, wherein: In step (4), during the preparation of the mechanical chemical polishing solution, the silica sol suspension and the antioxidant are mixed at room temperature and ultrasonically dispersed for 1 to 15 minutes.

10. A NdFeB electron backscatter diffraction sample, characterized in that: The NdFeB electron backscatter diffraction sample is prepared by the preparation method of any one of claims 1 to 9, wherein the surface of the NdFeB electron backscatter diffraction sample has no ion damage, amorphization or stress defects, the Kikuchi pattern signal-to-noise ratio is ≥6:1, and the grain boundary resolution reaches 0.1 micron.

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