Low-melting-point alloy for EBSD sample preparation, preparation method, EBSD sample preparation method and application

Abstract

The invention relates to the technical field of material analysis and testing, and discloses a low-melting-point alloy for EBSD sample preparation, a preparation method of the low-melting-point alloy, an EBSD sample preparation method and application of the EBSD sample preparation method, and the low-melting-point alloy for EBSD sample preparation comprises, by weight, 13-32% of Sn, 40-50% of Bi, 20-45% of In and 1.5-2.0% of Ag. The melting point of the low-melting-point alloy for EBSD sample preparation ranges from 60 DEG C to 75 DEG C. The low-melting-point alloy for EBSD sample preparation has the advantages of low cost and high performance. By adopting the alloy with optimized alloy components as the inlay material and optimizing the sample preparation process, the problems of poor fluidity, insufficient oxidation resistance and the like of the inlay material in the prior art are solved, and the success rate of EBSD sample preparation of the porous material or loose powder and the accuracy of analysis data are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material analysis testing, and mainly relates to a low-melting-point alloy for EBSD sample preparation, a preparation method thereof, an EBSD sample preparation method and application. BACKGROUND

[0002] In the process of electron backscatter diffraction (EBSD) sample preparation of porous materials, the prior art has many defects and deficiencies. Although the traditional epoxy resin inlay method has low cost, it has the problems of long curing time (usually 24-48 hours) and low hardness (Shore hardness ≤ 80), which easily leads to the falling off of powder particles during grinding and polishing, and the difference between the thermal expansion coefficient of the epoxy resin and that of the porous material is large, which easily produces interface stress and affects the accuracy of EBSD analysis. Although the liquid metal inlay technology represented by Ga-based alloy has advantages in fluidity and rapid prototyping, it has high cost (the price is about 500-1000 yuan / kg), and some Ga-based alloys are prone to alloying reaction with porous materials containing active elements such as Al and Mg, which interferes with the original crystal orientation analysis.

[0003] At present, the low-melting-point alloy (such as Sn-Bi-based alloy) used for inlaying of porous materials has relatively low cost, but has the problems of poor oxidation resistance and insufficient liquid flowability, and it is difficult to effectively fill the small pores (pore diameter < 5 μm) of the porous material, and it is easily oxidized at high temperature (> 100℃), which leads to the formation of an oxide film on the surface of the sample after sample preparation, affecting the quality of EBSD signal acquisition. In addition, there is little research on the optimization of alloy composition and the synergistic improvement of sample preparation process in the prior art to improve the sample preparation effect, which cannot meet the requirements of sample stability, conductivity and crystal orientation retention rate for EBSD sample preparation of porous materials. Therefore, the prior art still needs to be improved and developed. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a low-melting-point alloy for EBSD sample preparation, a preparation method thereof, an EBSD sample preparation method and application, which aims to solve the problems of poor oxidation resistance and insufficient liquid flowability of the existing low-melting-point alloy used for inlaying of porous materials.

[0005] The technical scheme of the present application is as follows: A low-melting-point alloy for EBSD sample preparation, wherein the low-melting-point alloy comprises the following raw materials in terms of weight percentage: Sn 13~32%, Bi 40~50%, In 20~45%, Ag 1.5~2.0%; The melting point of the low-melting-point alloy for EBSD sample preparation is between 60~75℃.

[0006] The alloy melting point can be controlled between 60-75℃ by using the above component ratio, while ensuring the low melting point characteristics, the alloy microstructure is refined by adding Ag, the liquid viscosity is reduced, and the penetration ability to the loose powder pores is enhanced.

[0007] A preparation method of a low melting point alloy for EBSD sample preparation as described above, comprising the following steps: After weighing Sn, Bi, In and Ag in proportion, heat to completely melt the metal raw material under inert gas protection atmosphere to obtain liquid alloy raw material; Pour the liquid alloy raw material into a copper mold and rapidly solidify to obtain the low melting point alloy for EBSD sample preparation.

[0008] The preparation method of a low melting point alloy for EBSD sample preparation of the present application uses alloy raw material with specific component ratio, and forms an inlay material with low melting point, high fluidity and oxidation resistance through the preparation process of melting, ultrasonic stirring and rapid solidification.

[0009] The preparation method of a low melting point alloy for EBSD sample preparation, wherein the inert gas is argon; The heating process is heated to 150-200℃ at a heating rate of 2-5℃ / min; After the metal raw material is completely melted, the following steps are further included: Ultrasonic stirring treatment is performed for 15-25 minutes; The frequency of the ultrasonic is 25-35kHz, and the power is 300-500W.

[0010] The preparation method of a low melting point alloy for EBSD sample preparation, wherein the copper mold is preheated to 60-80℃; The cooling rate in the rapid solidification process is ≥50℃ / s.

[0011] An EBSD sample preparation method, wherein the low melting point alloy for EBSD sample preparation as described above is used as an inlay material.

[0012] The EBSD sample preparation method, comprising the following steps: Put the sample into the mold, add the low melting point alloy for EBSD sample preparation heated to liquid state, seal the mold, vacuumize, fill nitrogen gas for pressurization, immerse in liquid nitrogen for solidification, and obtain an inlay sample.

[0013] The EBSD sample preparation method, wherein the heating is heated to 10-20℃ above the melting point of the low melting point alloy for EBSD sample preparation; The vacuumization is vacuumized to a vacuum degree ≤10 -3 Pa. The vacuum state is maintained for 10-15 minutes; The nitrogen gas filling and pressurizing is filling 0.8-1.2 MPa nitrogen gas; The nitrogen gas filling and pressurizing state is maintained for 5-8 minutes.

[0014] The EBSD sample preparation method, wherein, before the step of placing the sample into the mold, the sample is pretreated, specifically comprising the following steps: The sample is ultrasonically cleaned in anhydrous ethanol and vacuum dried; The ultrasonic cleaning time is 10-15 minutes; The vacuum drying temperature is 60-80°C.

[0015] The EBSD sample preparation method, wherein, the EBSD sample preparation method further comprises the following steps: The mosaic sample is surface treated; The surface treatment process is grinding and polishing and ion beam polishing treatment of the surface of the mosaic sample; The grinding and polishing is automatic grinding and polishing or manual sandpaper polishing; During the ion beam polishing treatment, Ar + Ion beam, energy 1.5-5 keV, treatment 1-2 h, inclination angle 3-5°, rotation speed 4-6 r / min, cycle 1-3 times.

[0016] The application of the EBSD sample preparation method described above, wherein the EBSD sample preparation method is used for EBSD sample preparation of loose powder or porous material.

[0017] Beneficial effects: the low melting point alloy for EBSD sample preparation of the application, which is Sn-Bi-In-Ag alloy, has the advantages of low cost and high performance. By using an alloy with optimized alloy composition as the inlay material and optimizing the sample preparation process, the problems of poor flowability and insufficient oxidation resistance of the inlay material in the prior art are solved, and the success rate of EBSD sample preparation of porous materials or loose powder and the accuracy of analysis data are improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a flowchart of the preparation method of the low melting point alloy for EBSD sample preparation and the EBSD sample preparation method of the application.

[0019] Figure 2 It is a graph of the determination results of the melting points of Sn-Bi-In-Ag alloys with different weight percentages in Example 1 of the application.

[0020] Figure 3 SEM image of the foamed nickel material before sample preparation in Example 1 of the present application.

[0021] Figure 4 SEM image of the inlaid sample after sample preparation in Example 1 of the present application.

[0022] Figure 5 Elemental mapping of the inlaid sample after sample preparation in Example 1 of the present application.

[0023] Figure 6 SEM image (left) and EBSD-IPF image (right) of the same area of the inlaid sample after sample preparation in Example 1 of the present application.

[0024] Figure 7 SEM image (left) and EBSD-IPF image (right) of the same area of the sample after sample preparation in Comparative Example 1 of the present application.

[0025] Figure 8 SEM image of the inlaid sample after sample preparation in Comparative Example 2 of the present application.

[0026] Figure 9 Elemental mapping of the inlaid sample after sample preparation in Comparative Example 2 of the present application.

[0027] Figure 10 SEM image (left) and EBSD-IPF image (right) of the same area of the sample after sample preparation in Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0028] The present application provides a low-melting-point alloy for EBSD sample preparation, a preparation method, an EBSD sample preparation method and application. In order to make the purpose, technical scheme and effects of the present application more clear and explicit, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0029] The present application provides a low-melting-point alloy for EBSD sample preparation, which is a Sn-Bi-In-Ag alloy, having the advantages of low cost and high performance.

[0030] Specifically, the low-melting-point alloy for EBSD sample preparation comprises the following raw materials in terms of weight percentage: Sn 13~32%, Bi 40~50%, In 20~45%, Ag 0.8~2.0%, and the balance is inevitable impurities.

[0031] The alloy melting point can be controlled between 60-85℃ by using the above component ratio, while ensuring the low melting point characteristics, the Ag addition refines the alloy microstructure, reduces the liquid viscosity, and enhances the penetration ability to the loose powder pores. Preferably, the low melting point alloy for EBSD sample preparation comprises the following raw materials according to weight percentage: Sn 13-32%, Bi 40-50%, In 20-45%, Ag 1.5-2.0%, and the balance is inevitable impurities.

[0032] The alloy melting point can be controlled between 60-75℃ by using the above component ratio.

[0033] Specifically, the low melting point alloy for EBSD sample preparation of the application has the following advantages: (1) Significant cost advantage: the low melting point alloy for EBSD sample preparation of the application has a cost controlled at ≤100 yuan / kg, which is reduced by more than 80% compared with Ga-based alloy, greatly reducing the sample preparation cost.

[0034] (2) Performance optimization: the alloy melting point is controlled between 60-75℃, ensuring the low melting point characteristics; by adding a specific proportion of Ag, the alloy grain is refined, the liquid viscosity is reduced to 3-5 mPa・s, the alloy fluidity is improved by more than 30%, which can effectively fill the micron-level pores (pore diameter ≥1 μm) of porous materials or loose powders, and the interface between the alloy and the sample is tightly combined; at the same time, the oxidation characteristics of Ag and other elements in the alloy synergistically act, reducing the oxidation weight gain rate of the alloy at 100℃ by 40%, improving the stability of the sample during sample preparation and testing, and there is no obvious reaction at the interface between the alloy and the sample. The application also provides a preparation method of the above-mentioned low melting point alloy for EBSD sample preparation, as shown in Figure 1 The preparation method comprises the following steps: After Sn, Bi, In and Ag are weighed according to the proportion, they are mixed and loaded into a crucible, which is placed in a furnace body such as a smelting furnace or a tube furnace, heated to 150-200℃ at a heating rate of 2-5℃ / min under an inert gas protection atmosphere, the metal raw materials are completely melted, ultrasonic stirring (frequency 25-35 kHz, power 300-500 W) is performed for 15-25 minutes to break the Ag nanoparticle agglomerates and ensure uniform dispersion of the metal raw materials, and a liquid alloy raw material is obtained; After smelting is completed, the liquid alloy raw material is cast into a copper mold preheated to 60-80℃, and an alloy ingot is prepared by a rapid solidification process (cooling rate ≥50℃ / s), which is the low melting point alloy for EBSD sample preparation of the application. In the preparation method, the process of heating to melt the metal raw material needs to be carried out in an inert gas protection atmosphere. In the embodiment of the present application, the inert gas is argon. In the preparation method, the heating rate should not be too high, and the heating rate needs to be controlled between 2-5 ℃ / min. First, to prevent "local overheating" and "component burning loss", and to avoid the alloy component deviating from the design: if the heating rate is too high, the heat cannot be quickly and uniformly conducted inside the alloy raw material, and "local hot spots" are easy to appear: even if the whole is not completely melted, the temperature in the local area may be far above the melting point (such as more than 300 ℃), causing the low-boiling-point or easily-volatile components (such as bismuth, indium) to evaporate preferentially. Second, to avoid "layering segregation" and ensure the uniformity of the molten alloy component: if the heating rate is too high, in the process of the alloy from "solid state→ semi-molten state→ fully molten state", the low-melting-point components (such as the liquid phase in the eutectic component) that are first melted will flow quickly due to the density difference, while the high-melting-point components (such as solid particles) that have not been melted will still be in a solid state due to the lagging heating, and cannot be fully mixed with the liquid phase, eventually leading to "upper and lower layering" of the alloy after full melting: the components with large density (such as bismuth) sink, and the components with small density (such as gallium, tin) float, forming "component segregation".

[0035] In the preparation method, the copper mold is preheated to 60-80 ℃ before casting, and the core is to solve the common defects in the casting process by adjusting the temperature matching of the mold and the casting material, the interface action and the forming environment, optimize the forming quality and efficiency, avoid the "rapid cooling defects" of the casting material, improve the forming integrity, and ensure the uniformity of solidification.

[0036] In the preparation method, the liquid alloy is cooled by using a rapid solidification process with a cooling rate ≥50 ℃ / s. The application of low-melting-point alloys prepared by traditional slow cooling process is limited to "low strength, low stability" scenarios (such as mold filling, temporary support); and the rapid solidification process, through the core mechanism of "refining grains + inhibiting segregation + constructing non-equilibrium structure", not only retains the advantages of low-melting-point alloys "low-temperature forming, good flexibility", but also makes up for the short board of "low strength, poor corrosion resistance". By using the rapid solidification process, the mechanical properties can be significantly improved through microstructure regulation: the strength and hardness are doubled, and the toughness is considered; the corrosion resistance and thermal stability are improved: the service life is prolonged; at the same time, by using the rapid solidification process, the alloy structure can be refined, the interface reaction activity can be reduced, and the erosion of the liquid alloy to the sample can be reduced.

[0037] The preparation method of the low-melting-point alloy for EBSD sample preparation of the present application forms an inlay material with low melting point, high fluidity and oxidation resistance by using alloy raw materials with specific component proportions, through the preparation process of melting, ultrasonic stirring and rapid solidification.

[0038] The application also provides an EBSD sample preparation method based on the low-melting-point alloy for EBSD sample preparation, which solves the problems of poor flowability, insufficient oxidation resistance, and easy interface reaction between the sample and the inlay material in the prior art by using an alloy with optimized alloy composition as the inlay material and optimizing the sample preparation process, thereby improving the success rate of EBSD sample preparation of porous materials or loose powders and the accuracy of analysis data.

[0039] Specifically, the EBSD sample preparation method of the application uses the low-melting-point alloy for EBSD sample preparation to inlay the sample, as shown in the following steps. Figure 1 (1) Pretreatment of the sample: The sample is ultrasonically cleaned in anhydrous ethanol for 10-15 minutes to remove surface impurities, and then dried in a vacuum drying oven at 60-80°C for 2-3 hours.

[0040] In this step, the sample is preferably a porous material, which can be a porous ceramic, a metal foam, or the like. In addition, the EBSD sample preparation method of the application is also applicable to EBSD sample preparation of loose powders, and therefore, the sample can also be a loose powder, which can be a nano-powder.

[0041] In this step, there is no special requirement for the power and frequency used for ultrasonic cleaning, and generally, 2-3 cycles of cleaning for 5-10 minutes at a power of 40-100 W can be used.

[0042] (2) Inlaying to prepare an inlaid sample: The pretreated sample is placed in a mold on a vacuum heating table, and a liquid Sn-Bi-In-Ag alloy heated to 10-20°C above the melting point is added. After sealing the mold, vacuum is drawn to a vacuum degree of ≤10 -3 Pa for 10-15 minutes to discharge the gas in the pore structure of the sample, and then 0.8-1.2 MPa of nitrogen gas is filled in for 5-8 minutes to allow the liquid alloy to fully penetrate into the pore structure of the sample. The infiltrated sample is immersed in liquid nitrogen (-196°C) for rapid solidification for 1-2 minutes to obtain a solidified inlaid sample.

[0043] The pore structure includes pores and gaps. The pores refer to the inherent channels inside the sample material, and the gaps refer to the voids between the sample particles, which are collectively referred to as pore structure.

[0044] In this step, the sample is inlaid by using a sample preparation process combining vacuum-assisted infiltration and low-temperature solidification. The pretreated sample is subjected to vacuum pumping and nitrogen pressurization, and then combined with the process of rapid solidification in liquid nitrogen to achieve efficient filling of the liquid alloy into the pore structure of the sample and rapid shaping of the sample. (3) Surface treatment of the inlaid sample:​ After polishing the mosaic sample, the surface of the mosaic sample is treated by ion beam polishing to remove the deformation layer and the oxide film on the surface layer, and a surface of the mosaic sample satisfying the requirements of EBSD analysis is obtained.

[0045] In this step, Ar + The ion beam has an energy of 1.5-5 keV, and the sample is treated for 1-2 h at an inclination angle of 3-5° and a rotation speed of 4-6 r / min, and the process is repeated 1-3 times. By optimizing the ion beam polishing parameters, the deformation layer and the oxide film can be accurately removed while maintaining the original crystal orientation of the sample.

[0046] Further, the process of treating the sample for 1-2 h with an energy of 1.5-5 keV can be divided into two stages. In the first stage, the sample is treated for 30 min-1 h with an energy of 3-5 keV, and in the second stage, the sample is treated for 30 min-1 h with an energy of 1.5-2 keV. When the energy is high, the treatment time is relatively reduced. The first stage plays a rough cleaning role, and the second stage plays a fine finishing role. By repeating the process 1-3 times, the treatment effect of the sample can be ensured.

[0047] In this step, the polishing method can be automatic polishing or manual sandpaper polishing, and the polishing process can be stopped when the surface of the mosaic sample is smooth and has few scratches.

[0048] The EBSD sample preparation method of the present application has the following advantages: (1) Improved sample preparation efficiency and quality: The use of vacuum-assisted infiltration and low-temperature curing processes can shorten the sample preparation period to less than 1 hour. The use of ion beam polishing technology can ensure that the surface of the mosaic sample has a smoothness of Ra≤50 nm, effectively improving the accuracy and reliability of EBSD analysis data, and increasing the EBSD analysis rate.

[0049] (2) Wide application range: The EBSD sample preparation method of the present application is suitable for a variety of porous materials, including but not limited to porous ceramics, metal foams, etc., and avoids interfacial reactions between the alloy and the sample. It can be widely used in microstructure analysis in the fields of material science, geology, metallurgy, etc. In addition, the EBSD sample preparation method of the present application can also be used for EBSD sample preparation of loose powders. The loose powders can be nanometer powders.

[0050] The present application also provides the application of the above-mentioned EBSD sample preparation method. The EBSD sample preparation method is used for EBSD sample preparation of porous materials or loose powders, and the low-melting-point alloy used for EBSD sample preparation is used as the embedding material of the porous materials or loose powders. The porous materials can be porous ceramics, metal foams, etc. The loose powders can be nanometer powders, etc. The EBSD sample preparation method is particularly suitable for microstructure analysis of porous materials or loose powders.

[0051] The conventional EBSD testing equipment operation and conventional parameter setting when performing EBSD testing on the inlaid sample are also provided in the scheme of the present application, and the parameter setting of the inlaid sample in the embodiment is specifically as follows: (1) Inlaid sample fixation: the inlaid sample is fixed on the EBSD special sample table with conductive glue (such as silver glue), and it is ensured that the surface of the inlaid sample is perpendicular to the electron beam (the inclination angle is usually 70°, which can be adjusted according to the equipment).

[0052] (2) SEM parameter debugging: acceleration voltage: usually 10-30 kV, high voltage can increase the electron beam penetration depth, which is suitable for thicker porous materials or powder particles; low voltage (such as 15 kV) can improve the spatial resolution, which is suitable for nanoscale powders. Beam intensity: controlled at 10 -10 ~10 -9 A, to avoid overheating of the sample or damage to the powder particles caused by strong beam (liquid metal inlay can alleviate thermal damage, but optimization is still needed). Working distance: kept at 10-18 mm to ensure good electron beam focusing and strong backscattered electron signal intensity.

[0053] (3) EBSD detector parameter setting: the acquisition rate is adjusted according to the size of the porous material or the size of the powder particle and the testing accuracy, and the rate needs to be reduced for small powders (<10 μm) to increase the acquisition time of each point (such as 50 ms / point) to obtain clear Kikuchi patterns. The step size should be less than 1 / 5-1 / 10 of the average size of the powder particles to ensure the accuracy of the orientation statistics. A reasonable threshold value (such as 50-100, which can be adjusted according to the equipment model) is set to filter low-quality patterns and avoid data errors.

[0054] The present application is further described below through specific examples.

[0055] Example 1 Alloy preparation: Sn 13%, Bi 40%, In 45%, and Ag 2% by weight percentage are weighed and placed in a melting furnace, and then heated to 180°C at a rate of 5°C / min under argon protection. After the metal raw materials are completely melted, ultrasonic stirring (frequency 30 kHz, power 400 W) is performed for 20 minutes, and then the Sn-Bi-In-Ag alloy ingot is rapidly solidified (cooling rate ≥ 50°C / s) by pouring into a preheated copper mold at 70°C, and then broken for use. In addition, other Sn-Bi-In-Ag alloys are prepared according to the following different weight percentages, and the preparation method is the same as above: (1) Sn 23%, Bi 46%, In 30%, and Ag 1% by weight percentage are weighed; (2) Sn 31.2%, Bi 48%, In 20%, and Ag 0.8% by weight percentage are weighed; (3) Sn 18%, Bi 42.5%, In 38%, Ag 1.5% by weight percentage; (4) Sn 16%, Bi 50%, In 33%, Ag 1% by weight percentage; The melting point of each Sn-Bi-In-Ag alloy prepared was determined, and the results are shown in Table 1. Figure 2 The melting points of each Sn-Bi-In-Ag alloy were 62.24℃, 81.33℃, 81.65℃, 73.06℃, and 82.34℃, respectively.

[0056] The first Sn-Bi-In-Ag alloy (i.e., In 45 Bi 40 Sn 13 Ag2) was used to prepare the sample of the foamed nickel.

[0057] The sample preparation process was as follows: foamed nickel material 10mm*10mm*5mm was ultrasonically cleaned in ethanol for 12 minutes and vacuum dried at 80℃ for 2.5 hours. The treated foamed nickel material was placed in a mold on a vacuum heating table, and liquid Sn-Bi-In-Ag alloy heated to 80℃ was added. Vacuum was drawn to 10 -4 Pa for 12 minutes, 1 MPa nitrogen was filled for 6 minutes, and then the sample was immersed in liquid nitrogen for 1.5 minutes to obtain an inlaid sample. After the inlaid sample was automatically ground and polished to have a smooth surface with few grinding marks, the sample surface was treated by ion beam polishing (Ar⁺ ion beam, energy 4keV for 30min, 1.5keV for 1h, rotation speed 5r / min, inclination angle 3°, cycle 1), and the sample preparation was completed.

[0058] Before sample preparation, the microstructure of the foamed nickel material was observed, Figure 3 which is a SEM image of the foamed nickel material before sample preparation. It can be seen that the foamed nickel material before sample preparation has a clear pore structure and low surface flatness. Figure 3

[0059] After sample preparation, the microstructure of the inlaid sample (i.e., Sn-Bi-In-Ag low melting point alloy inlaid foamed nickel material) was observed, and element area scanning was performed on the inlaid sample. Figure 4 which is a SEM image of the inlaid sample, Figure 5 which is an element area distribution map of the inlaid sample. By comparing Figures 3-5 it can be seen that the surface flatness of the inlaid sample is increased, and the interface between the Sn-Bi-In-Ag alloy and the foamed nickel material is tightly combined, indicating that the Sn-Bi-In-Ag alloy has good fluidity, and there is no element penetration between the Sn-Bi-In-Ag alloy and the sample, proving that there is no obvious reaction at the interface between the Sn-Bi-In-Ag alloy and the sample.​

[0060] EBSD analysis of the microstructure of the foamed nickel material was successfully achieved, and the results are shown in Figure 6 It can be seen from Figure 6 that the flatness of the inlaid sample is high, and the EBSD resolution rate is high.

[0061] Comparative Example 1 The sample preparation process was as follows: foamed nickel material 10mm*10mm*5mm was ultrasonically cleaned in ethanol for 20 minutes and vacuum dried at 60°C for 5 hours. After automatic grinding and polishing to obtain a flat surface with few grinding marks, the sample surface was treated by ion beam polishing (Ar+ ion beam, energy 5keV for 20min, 2keV for 0.5h, rotation speed 5r / min, inclination angle 5°, cycle 2 times) to complete the sample preparation.

[0062] EBSD testing was performed on the sample at a magnification of 500 times, and the sample resolution rate was only 6.36% (including pores), making it difficult to achieve EBSD analysis of the microstructure of the foamed nickel material, and the results are shown in Figure 7 It can be seen from Figure 7 that the flatness of the sample after sample preparation is low, and the EBSD resolution rate is low.

[0063] Comparative Example 2 The sample preparation process was as follows: foamed nickel material 10mm*10mm*5mm was ultrasonically cleaned in ethanol for 15 minutes and vacuum dried at 70°C for 3 hours. The treated foamed nickel material was placed in a hot inlay instrument with conductive carbon inlay material on the bottom, and conductive carbon inlay material was continuously added until it completely covered the foamed nickel material. After heating to 190°C for 8min and cooling, an inlaid sample was obtained. After automatic grinding and polishing of the inlaid sample to obtain a flat surface with few grinding marks, the sample surface was treated by ion beam polishing (Ar+ ion beam, energy 5keV for 30min, rotation speed 8r / min, inclination angle 2°) to complete the sample preparation.

[0064] After sample preparation, the microstructure of the inlaid sample (i.e. conductive carbon inlay material inlaid foamed nickel material) was observed, and element mapping of the inlaid sample was performed. Figure 8 The SEM image of the inlaid sample is Figure 9 The element distribution map of the inlaid sample is shown. By comparing Figures 8-9 it can be seen that the interface between the conductive carbon inlay material and the foamed nickel material is not dense, and there are cases of insufficient filling and cracks.

[0065] EBSD testing was performed on the inlaid sample at a magnification of 500 times, and the sample resolution rate was only 35% (including conductive carbon inlay material), and the EBSD testing was as follows:Figure 10 The flatness of the mosaic sample is not high, and the EBSD resolution is not high. Figure 10 It can be seen that the flatness of the mosaic sample is not high, and the EBSD resolution is not high.

[0066] It should be understood that the application of the present application is not limited to the above examples, and those of ordinary skill in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the present application.

Claims

1. A low melting point alloy for EBSD specimen preparation, characterized in that, According to the percentage by weight, comprising the following raw materials: Sn 13~32%, Bi 40~50%, In 20~45%, Ag 1.5~2.0%; The melting point of the low melting point alloy for EBSD sample preparation is between 60~75℃.

2. A method of producing a low melting point alloy for EBSD sample making as claimed in claim 1, characterized in that, Comprising the following steps: After weighing Sn, Bi, In and Ag in proportion, heat to complete melting of the metal raw materials under the protection of inert gas atmosphere to obtain liquid alloy raw materials; Pour the liquid alloy raw materials into a copper mold and rapidly solidify to obtain the low melting point alloy for EBSD sample preparation.

3. The method of claim 2, wherein the low melting point alloy is prepared by the steps of: melting the alloy; and cooling the alloy to room temperature. The inert gas is argon; The heating process is to heat to 150~200℃ at a heating rate of 2~5℃ / min; After heating to complete melting of the metal raw materials, the following steps are further included: Ultrasonic stirring treatment for 15~25 minutes; The frequency of the ultrasonic is 25~35kHz, and the power is 300~500W.

4. The method of claim 2, wherein the low melting point alloy is prepared by the steps of: melting a base alloy; adding a trace amount of a rare earth element to the base alloy; and stirring the base alloy and the trace amount of the rare earth element. The copper mold is preheated to 60~80℃; The cooling rate during the rapid solidification is ≥50℃ / s.

5. An EBSD sample preparation method, characterized by, The low melting point alloy for EBSD sample preparation as claimed in claim 1 is used as an inlay material.

6. The EBSD sample preparation method of claim 5, wherein, Comprising the following steps: Put the sample into a mold, add the low melting point alloy for EBSD sample preparation heated to liquid state, seal the mold, vacuumize, fill nitrogen gas for pressurization, immerse in liquid nitrogen for solidification to obtain an inlay sample.

7. The EBSD sample preparation method of claim 6, wherein, The heating is to heat to 10~20℃ above the melting point of the low melting point alloy for EBSD sample preparation; The vacuuming is to a vacuum of <10 -3 Pa; The vacuum state is maintained for 10~15 minutes; The nitrogen gas pressurization is to fill nitrogen gas at 0.8~1.2MPa; The nitrogen gas pressurization state is maintained for 5~8 minutes.

8. The EBSD sample preparation method of claim 6, wherein, Before the step of putting the sample into the mold, the sample is pretreated, specifically comprising the following steps: Ultrasonic cleaning of the sample in anhydrous ethanol, vacuum drying; The ultrasonic cleaning time is 10-15 minutes; The vacuum drying temperature is 60-80℃.

9. The EBSD sample preparation method of claim 6, wherein, The EBSD sample preparation method further comprises the following steps: Surface treatment of the inlay sample; The surface treatment process is to perform grinding and polishing and ion beam polishing treatment on the surface of the inlay sample; The grinding and polishing is automatic grinding and polishing or manual sandpaper polishing; Ar is used in the ion beam polishing process + Ion beam, energy 1.5~5keV, processing 1-2h, inclination angle 3~5°, rotation speed 4~6 r / min, cycle 1-3 times.

10. Use of an EBSD sample preparation method according to any one of claims 5-9, characterized in that The EBSD sample preparation method is used for EBSD sample preparation of loose powder or porous material.

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