Method for in-situ observation of Ti alloy sample through high-temperature laser confocal microscope

Abstract

The invention belongs to the technical field of in-situ observation sample preparation, and particularly relates to a method for in-situ observation of a Ti alloy sample through a high-temperature laser confocal microscopy, and the method comprises the following steps: S1, grinding, polishing and ultrasonic cleaning treatment of Ti alloy; s2, performing plasma spraying treatment on the alumina crucible, and spraying a layer of yttrium oxide powder on the surface of the alumina crucible; s3, hanging a pure titanium sheet in a hearth of the high-temperature laser confocal microscope; and S4, the Ti alloy sample pretreated in the step S1 is put into a crucible, and in-situ observation is conducted through a high-temperature laser confocal microscope. The method is simple to operate, solves the problems that the Ti alloy is easy to oxidize at high temperature and is not provided with an adaptive observation crucible, and can be used for observing the microstructure evolution of the Ti alloy in situ and observing the microstructure evolution process of the Ti alloy in real time under the high-temperature laser confocal microscope so as to facilitate the subsequent research on growth mechanism analysis and growth kinetics quantification.

Description

Technical Field

[0001] This invention specifically relates to a method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope, belonging to the field of in-situ observation sample preparation technology. Background Technology

[0002] Since its discovery, titanium has gradually become an important structural metallic material due to its low density, high specific strength, and good corrosion resistance. Pure titanium can rapidly form a stable and dense oxide film in air, maintaining excellent chemical stability even in high-temperature, humid, and chlorine-containing environments. Through reasonable alloying and hot working processes, different types of titanium alloys can simultaneously possess high strength, good toughness, and corrosion resistance, thus finding wide application in engineering fields.

[0003] Over the past few decades, the intersection of materials science and biomedical engineering has driven the development of novel implant materials. Titanium and its alloys, with their excellent biocompatibility, suitable elastic modulus, and unique osseointegration capabilities, have rapidly become widely recognized medical metallic materials in clinical practice. Their ability to directly and stably bond with bone tissue has laid the foundation for the development of modern dental implants and orthopedic implants. Titanium alloys are currently widely used in orthopedic joint prostheses, spinal fixation devices, internal fixation devices for trauma, dental implants, and related instruments. In addition to structural components that withstand cyclic loads, titanium alloys are also used in cardiovascular implants, such as stents, artificial heart valves, pacemaker housings, and long-term implanted sensors, where the reliability requirements for long-term service are even more stringent.

[0004] Patent application CN119555459A discloses a method for preparing high-temperature titanium alloy metallographic samples. This method greatly improves the efficiency of preparing high-temperature titanium alloy metallographic samples. However, when using this method on alloys with high Ti content, the microstructure of the Ti alloy cannot be observed in the field of view during high-temperature observation.

[0005] Ti alloys are prone to oxidation and exhibit complex microstructure evolution at high temperatures, making the study of their high-temperature microstructure evolution challenging. Laser confocal microscopy, with its ability to perform high-temperature heating and real-time observation of microstructures, is an important tool for studying the high-temperature microstructure evolution of metallic materials. However, the oxidation sensitivity and surface morphology changes of high-Ti alloys under high-temperature conditions make the preparation of in-situ observation samples more challenging. For example, thick oxide layers easily form on the surface, and sample edges are prone to warping or deformation, thus affecting imaging quality and experimental reliability. In addition, traditional alumina crucibles react with Ti, causing the alloy to adhere to the crucible during heating, making it impossible to observe the microstructure of the Ti alloy in the field of view; yttrium oxide crucibles have poor thermal shock resistance and are prone to cracking during heating.

[0006] In summary, existing technologies have obvious shortcomings. Therefore, developing a sample preparation method for high-Ti alloys suitable for high-temperature laser confocal microscopy is of great significance for obtaining clear and stable in-situ observation images and accurately analyzing their high-temperature phase transformation and microstructure evolution behavior. It also provides key technical support for a deeper understanding of the service mechanism of high-Ti alloys in aerospace, biomedical, and highly corrosive environments. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by providing a method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope. This method is simple to operate, solves the problems of easy oxidation of Ti alloys at high temperatures and the lack of suitable observation crucibles, and enables in-situ observation of the microstructure evolution of Ti alloys under a high-temperature laser confocal microscope, allowing for real-time observation of the microstructure evolution process of Ti alloys, so as to facilitate subsequent research on growth mechanism analysis and quantitative analysis of growth kinetics.

[0008] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope, applicable to Ti alloys with a Ti content of 53 at.% or higher, comprising the following steps: Pretreatment of S1 and Ti alloys: The Ti alloys are ground, polished, and ultrasonically cleaned. S2. Perform plasma spraying treatment on the alumina crucible, and spray a layer of yttrium oxide powder on its surface; S3. Suspend pure titanium sheets inside the furnace of a high-temperature laser confocal microscope; S4. Place the Ti alloy sample pretreated in step S1 into the crucible treated in step S2, and observe it in situ using a high-temperature laser confocal microscope.

[0009] Furthermore, the Ti content in the Ti alloy is 53 at.% to 80 at.%, preferably 53 at.% to 61 at.%, 61 at.% to 70 at.%, or 70 at.% to 80 at.%.

[0010] Further, in step S1, the surface is polished until the roughness is less than 3μm.

[0011] Further, in step S1, a diamond polishing paste with a thickness of 0.25μm to 1.0μm is used for polishing, preferably a diamond polishing paste with a thickness of 0.25μm.

[0012] Furthermore, in step S2, the yttrium oxide powder is spherical yttrium oxide powder with an analytical purity of 99.9% and a particle size of 35 μm to 50 μm.

[0013] Further, in step S2, the powder feeding rate for plasma spraying is 30 g / min to 60 g / min, and the process includes: First layer: working current 500A~600A, working voltage 35V~45V, spraying thickness 30μm~50μm; Second layer: working current 650A~700A, working voltage 50V~75V, spraying thickness 50μm~70μm; The third layer has an operating current of 500A~600A, an operating voltage of 35V~45V, and a coating thickness of 30μm~60μm.

[0014] Furthermore, in step S2, the plasma arc moving speed of the plasma spraying treatment is 70mm / s to 90mm / s, and the working distance is 90mm to 110mm; preferably, the plasma arc moving speed is 80mm / s and the working distance is 100mm.

[0015] Furthermore, in step S2, the coating thickness is 130μm~180μm; Furthermore, the crucible obtained through step S2, after undergoing working conditions of heating at a rate of 50K / min to 100K / min, maintaining a temperature range of 1278K for 20 to 30 seconds, and cooling down to room temperature at a rate of 50K / min to 200K / min, exhibits a difference in the coefficient of linear expansion of less than 5%.

[0016] Furthermore, in step S3, the pure titanium foil is 99.99% analytical grade.

[0017] Furthermore, in step S4, the flow rate of the inert gas during observation is 100 mL / min to 150 mL / min.

[0018] The beneficial effects of this invention are: (1) The method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope provided by the present invention establishes a controlled layered interface structure between the Ti alloy sample and the crucible substrate by forming a continuous and stable yttrium oxide isolation layer on the surface of the alumina crucible. The yttrium oxide isolation layer forms a strong physical bond with the alumina crucible, so that only a weak interface interaction is formed between the Ti alloy and the crucible during heating and solidification. In a pure argon environment, the flow rate of the protective gas is precisely controlled to effectively dilute and remove residual oxygen in the furnace cavity, while ensuring that there is no significant airflow disturbance to the sample surface and imaging interface under high temperature conditions. Together, these measures effectively prevent the Ti alloy from undergoing interfacial reaction, adhesion, or irreversible bonding with the crucible material during high-temperature heating and solidification. At the same time, the surface undulations and morphological distortions caused by uneven interface constraints are suppressed, so that the sample can maintain a nearly flat surface morphology after solidification. Thus, a stable and continuous observation interface is obtained under a high-temperature laser confocal microscope, which facilitates clear tracking of the nucleation, growth, and evolution process of the Ti alloy microstructure, and improves the imaging quality and experimental reliability of in-situ observation.

[0019] (2) The method for in-situ observation of Ti alloy samples by high temperature laser confocal microscope provided by the present invention is simple to operate and solves the problem that Ti alloy is easily oxidized at high temperature and there is no suitable observation crucible. It can observe the microstructure evolution of Ti alloy in situ under high temperature laser confocal microscope and observe the microstructure evolution process of Ti alloy in real time, so as to carry out subsequent growth mechanism analysis and growth kinetic quantification research. Attached Figure Description

[0020] Figure 1 These are photographs of the sample and crucible after in-situ observation using a high-temperature laser confocal microscope, as shown in Example 1. Figure 2 These are real-time photographs of the microstructure evolution observed in situ in Example 1; Figure 3 These are real-time photographs of the microstructure evolution observed in situ in Example 2; Figure 4 These are real-time photographs of the microstructure evolution observed in situ in Example 3; Figure 5 These are real-time photographs of the microstructure evolution observed in situ in Example 4; Figure 6 These are real-time photographs of the microstructure evolution observed in situ in Example 5; Figure 7 These are real-time photographs of the microstructure evolution observed in situ in Example 6; Figure 8 This is a photograph of the sample and crucible after in-situ observation using a high-temperature laser confocal microscope, as shown in Comparative Example 1. Figure 9 A real-time photograph of the microstructure evolution observed in situ in Comparative Example 1; Figure 10 Comparative Example 2: In-situ observation of the alloy sample surface using a high-temperature laser confocal microscope; Figure 11 The image shows the surface of the alloy sample observed in situ using a high-temperature laser confocal microscope, as shown in Comparative Example 4. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0023] This invention provides a method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope. This method is applicable to Ti alloys with a Ti content of 53 at.% or higher and includes the following steps: Pretreatment of S1 and Ti alloys: The Ti alloys are ground, polished, and ultrasonically cleaned. S2. Perform plasma spraying treatment on the alumina crucible, and spray a layer of yttrium oxide powder on its surface; S3. Suspend pure titanium sheets inside the furnace of a high-temperature laser confocal microscope; S4. Place the Ti alloy sample pretreated in step S1 into the crucible treated in step S2, and observe it in situ using a high-temperature laser confocal microscope.

[0024] Yttrium oxide powder exhibits good chemical compatibility with Ti alloys under high-temperature conditions. It does not readily react chemically with Ti and displays low interfacial wettability with molten or semi-molten Ti alloys. By forming a continuous and stable yttrium oxide isolation layer on the surface of an alumina crucible, a controlled layered interface structure is constructed between the Ti alloy sample and the crucible substrate. A strong physical bond is formed between the yttrium oxide isolation layer and the alumina crucible, while no significant chemical reaction occurs between yttrium oxide and the Ti alloy under high-temperature conditions, and the interfacial wettability is low. This results in only a weak interfacial interaction between the Ti alloy and the crucible during heating and solidification. In an inert environment, precise control of the protective gas flow rate effectively dilutes and removes residual oxygen from the furnace chamber, while ensuring that there is no significant airflow disturbance to the sample surface and imaging interface under high temperature conditions. Together, these measures effectively prevent interfacial reactions, adhesion, or irreversible bonding between the Ti alloy and the crucible material during high-temperature heating and solidification. At the same time, they suppress surface undulations and morphological distortions caused by uneven interfacial constraints, allowing the sample to maintain a nearly flat surface morphology after solidification. This enables the acquisition of a stable and continuous observation interface under a high-temperature laser confocal microscope, facilitating clear tracking of the nucleation, growth, and evolution of the Ti alloy microstructure and improving the imaging quality and experimental reliability of in-situ observation.

[0025] Specifically, the Ti content in the Ti alloy is 53 at.% to 80 at.%, preferably 53 at.% to 61 at.%, 61 at.% to 70 at.%, or 70 at.% to 80 at.%. More specifically, this invention provides a method for in-situ observation of high-Ti content Ti alloys using a high-temperature laser confocal microscope. As long as the Ti content is within the range defined by this invention, there are no specific requirements regarding the types and amounts of other components in the Ti alloy. To better explain the technology of this invention, the Ti alloy selected in the embodiments is a high-Ti content Ti-Cu alloy with dimensions of Ф5×3mm. The Ti alloy samples are: a Ti-Cu alloy with a Ti content of 53 at.% and a Cu content of 47 at.%; and a Ti-Cu alloy with a Ti content of 61 at.% and a Cu content of 39 at.%.

[0026] Specifically, in step S1, the surface is polished until there are no obvious scratches and the surface roughness is less than 3μm.

[0027] In some embodiments, the polishing process can be specifically operated by sequentially polishing the sides and upper and lower surfaces of the Ti alloy sample with 400-grit, 800-grit, 1500-grit, and 2000-grit sandpaper, with each grit taking 10-15 minutes to polish.

[0028] Specifically, in step S1, a diamond polishing paste with a diameter of 0.25μm to 1.0μm is used for polishing, preferably a diamond polishing paste with a diameter of 0.25μm, and the polishing time is 10 to 15 minutes.

[0029] Specifically, in step S2, the yttrium oxide powder is spherical yttrium oxide powder with an analytical purity of 99.9% and a particle size of 35μm~50μm.

[0030] When the yttrium oxide isolation layer thickness is within a reasonable range, a continuous and stable ceramic isolation interface can be formed on the crucible surface, blocking direct contact between the Ti alloy and the alumina substrate. This avoids localized exposure due to an excessively thin coating or thermal stress concentration and coating peeling risks caused by an excessively thick coating. In step S2, the powder feeding rate for plasma spraying is controlled at 30 g / min to 60 g / min, the plasma arc moving speed is 70 mm / s to 90 mm / s, and the working distance is 90 mm to 110 mm; preferably, the plasma arc moving speed is 80 mm / s and the working distance is 100 mm. Precise process control ensures the sequential formation of a dense layer, a porous layer, and a dense layer on the alumina crucible surface, forming an integral bonding layer. This is achieved by controlling the working current to... With an operating current of 500A~600A and an operating voltage of 35V~45V, a first dense layer with a spray thickness of 30μm~50μm is obtained; then, with an operating current of 650A~700A and an operating voltage of 50V~75V, a second loose layer with a spray thickness of 50μm~70μm is obtained; finally, with an operating current of 500A~600A and an operating voltage of 35V~45V, a third dense layer with a spray thickness of 30μm~60μm is obtained. To ensure that the yttrium oxide powder coating thickness is 130μm~180μm, the yttrium oxide coating maintains good structural integrity and bonding stability during high-temperature heating and cooling cycles. That is, after the crucible undergoes working conditions of heating rate of 50~100K / min, holding at 1278K for 20~30s, and cooling rate of 50~200K / min to room temperature, the difference in the coefficient of linear expansion is less than 5%, so that the Ti alloy forms a nearly flat surface morphology after solidification. This is beneficial for continuous and clear observation of the nucleation, growth and evolution process of its microstructure under a high-temperature laser confocal microscope, thereby improving the imaging quality and data reliability of in-situ observation experiments. In order to ensure that the above effects are not affected, in step S2, the yttrium oxide powder is spherical yttrium oxide powder with analytical purity of 99.9% and a particle size of 35μm~50μm; the size of the alumina crucible is Ф(5~8)×(4~6)mm, preferably Ф6.5×4mm. The shape and size of the alumina crucible only need to meet the requirements of the equipment and observation. The equipment requirement is that the maximum diameter should not exceed 9mm. The shape of the alumina crucible is generally cylindrical, and the shape can be selected according to the actual application environment. When the particle size of yttrium oxide powder is greater than 50μm, the powder will not be heated sufficiently during plasma spraying, and some particles will not be able to melt completely. This will result in unmelted or semi-melted particles during the deposition process, which will reduce the spreading ability and density of the coating, increase the internal porosity and surface roughness of the coating, and weaken the bonding strength between the coating and the alumina crucible substrate. In this way, the uniformity, stability and high-temperature performance of the yttrium oxide coating will be affected.

[0031] If the yttrium oxide isolation layer is too thick, it is prone to cracking or peeling during high-temperature heating and cooling due to thermal expansion mismatch and residual stress accumulation, thereby destroying the integrity of the isolation layer and potentially introducing additional temperature field disturbances, which is not conducive to the stable solidification process of Ti alloy and in-situ observation of microstructure.

[0032] Specifically, to reduce the oxygen content within the furnace of a high-temperature laser confocal microscope, an oxygen-absorbing material is placed on the support rod inside the cavity of the high-temperature laser confocal equipment. This material is pure Ti foil, with a size of 3 × 20 = 60 mm and an analytical purity of 99.99%. The quantity, size, and distribution of the pure Ti foil can be adjusted according to the furnace volume, heating temperature, and holding time to effectively suppress the oxidation of the Ti alloy sample during high-temperature experiments, thereby ensuring clear microscopic images are obtained under the high-temperature laser confocal microscope.

[0033] Specifically, the distance between the sample and the center of the pure Ti foil is 5~8mm.

[0034] More specifically, the Ti foil is folded in half and hung on the support rod. When there is only one pure Ti foil, it is located in the non-imaging area around or above the crucible, and its position is kept at a distance from the sample to be observed to avoid interfering with the sample's solidification process and microscopic imaging. When there are multiple pure Ti foils, they are distributed along the axial direction of the support rod in a dispersed manner to increase their contact area with the gas in the furnace. During high-temperature heating, the pure Ti foil preferentially absorbs residual oxygen in the furnace, thereby forming a relatively uniform low-oxygen environment in the furnace. This controls the oxidation of the Ti alloy sample surface to a level that does not affect its solidification process and in-situ observation of the microstructure. When the distance between the sample and the center of the pure Ti foil is less than 5 mm, the Ti foil will generate thermal radiation interference at high temperatures, which may change the local temperature distribution of the sample and thus affect the observation results.

[0035] Before the experiment, the furnace chamber of the high-temperature laser confocal microscope was cleaned three times with high-purity argon gas, and high-purity argon gas was continuously introduced during the experiment to prevent oxidation at high temperatures. During the high-temperature in-situ observation, the flow rate of the protective gas introduced into the furnace chamber was controlled to ensure that it was within a functional range that could effectively dilute and remove residual oxygen in the furnace chamber without causing significant airflow disturbance to the sample surface and imaging interface under high-temperature conditions. The flow rate of the inert gas was 100 mL / min to 150 mL / min, thereby suppressing the oxidation of the Ti alloy while ensuring the stability of the observed interface and the clarity of the image under the high-temperature laser confocal microscope.

[0036] Specifically, the inert gas is preferably high-purity argon with a purity of 99.99%.

[0037] Example 1 The method for in-situ observation of Ti alloy samples using high-temperature laser confocal microscopy includes the following steps: S1. Pretreatment of high Ti content Ti alloy: Take a Ф5×3mm metal block from the Ti-Cu alloy, wherein the Ti content in the Ti-Cu alloy is 61 at.% and the Cu content is 39 at.%. The Ti alloy sample is polished on the side and top and bottom surfaces with 400 grit, 800 grit, 1500 grit and 2000 grit sandpaper in sequence, and polished with 0.25μm diamond polishing paste. Then, it is ultrasonically cleaned with deionized water.

[0038] S2. Select spherical yttrium oxide powder of analytical purity (99.9%) with a particle size of 40 μm and perform plasma spraying treatment on the alumina crucible. The powder feeding rate of the plasma spraying treatment is 30 g / min to 60 g / min, the plasma arc moving speed is 80 mm / s, and the working distance is 100 mm. First, control the working current to 500 A to 600 A and the working voltage to 35 V to 45 V, and spray the first layer with a thickness of 40 μm. Then, control the working current to 650 A to 700 A and the working voltage to 50 V to 75 V, and spray the second layer with a thickness of 60 μm. Finally, control the working current to 500 A to 600 A and the working voltage to 35 V to 45 V, and spray the third layer with a thickness of 50 μm. Finally, a layer of yttrium oxide powder with a thickness of 150 μm is sprayed on the surface of the alumina crucible.

[0039] S3. A 99.99% pure titanium sheet was suspended inside the furnace of a high-temperature laser confocal microscope, with the distance between the sample and the center of the pure Ti foil being 6 mm. The furnace was purged three times with high-purity argon gas, and high-purity argon gas was continuously introduced at a flow rate of 100 mL / min to 150 mL / min.

[0040] S4. Place the Ti alloy sample pretreated in step S1 into the crucible treated in step S2, and observe it in situ using a high-temperature laser confocal microscope.

[0041] This embodiment uses high-temperature laser confocal microscopy to observe in situ the sample and crucible after the experiment, as shown in the photographs. Figure 1 As shown, the crucible and sample can completely detach after heating. Real-time images of the in-situ observed microstructure evolution are shown below. Figure 2 As shown, from Figure 2 The microstructure and evolution process of the alloy can be clearly observed.

[0042] Example 2 This embodiment uses the same method as Example 1 for in-situ observation using high-temperature laser confocal microscopy, the difference being that in step S1, the Ti-Cu alloy sample selected has a Ti content of 53 at.% and a Cu content of 47 at.%. Real-time images of the microstructure evolution observed in-situ using high-temperature confocal microscopy in this embodiment are shown below. Figure 3 As shown.

[0043] Example 3 This embodiment uses the same method as Example 1 for in-situ observation using high-temperature laser confocal microscopy, with the difference being: in step S2, the first layer is sprayed with a thickness of 30 μm, the second layer with a thickness of 50 μm, and the third layer with a thickness of 50 μm; finally, a 130 μm layer of yttrium oxide powder is sprayed onto the surface of the alumina crucible. Real-time images of the microstructure evolution observed in situ using high-temperature confocal microscopy in this embodiment are shown below. Figure 4 As shown.

[0044] Example 4 This embodiment uses the same method as Example 1 for in-situ observation using high-temperature laser confocal microscopy, with the difference being: in step S2, the first layer is sprayed with a thickness of 50 μm, the second layer with a thickness of 70 μm, and the third layer with a thickness of 60 μm; finally, a layer of yttrium oxide powder with a thickness of 180 μm is sprayed onto the surface of the alumina crucible. Real-time images of the microstructure evolution observed in situ using high-temperature confocal microscopy in this embodiment are shown below. Figure 5 As shown.

[0045] Example 5 This embodiment uses the same method as Example 1 for in-situ observation using high-temperature laser confocal microscopy, the difference being that in step S2, the particle size of the spherical yttrium oxide powder is 35 μm. Real-time images of the microstructure evolution observed in situ using high-temperature confocal microscopy in this embodiment are shown below. Figure 6 As shown.

[0046] Example 6 This embodiment uses the same method as Example 1 for in-situ observation using high-temperature laser confocal microscopy, the difference being that in step S2, the particle size of the spherical yttrium oxide powder is 50 μm. Real-time images of the microstructure evolution observed in situ using high-temperature confocal microscopy in this embodiment are shown below. Figure 7 As shown.

[0047] Examples 1-6, observed in situ using a high-temperature laser confocal microscope, showed that after the crucible was coated with a yttrium oxide coating according to the technology of this invention, the difference in the coefficient of linear expansion during high-temperature heating and cooling cycles was less than 5%. The coating exhibited good toughness and maintained a strong bond with the crucible, ultimately ensuring the integrity of the coating structure and meeting the coating's property requirements. This allowed for continuous and clear observation of the nucleation, growth, and evolution of the microstructure under a high-temperature laser confocal microscope. Observational results showed that, as seen in real-time images 2-7 from the in-situ observation under the high-temperature laser confocal microscope, the sample surface was roughly flat within the field of view, indicating a liquid-to-solid phase transition. The primary phase formed after the liquid phase solidified was clearly visible. The sample could be completely separated from the crucible after the experiment, indicating that no wetting reaction occurred during the experiment.

[0048] Comparative Example 1 This comparative example uses the same method as Example 1 for in-situ observation with high-temperature laser confocal microscopy. The difference is that steps S2 and S3 are omitted. That is, the Ti alloy sample after step S1 is directly placed into an alumina crucible, and the microstructure evolution of the alloy block is observed in-situ using high-temperature laser confocal microscopy.

[0049] This comparative high-temperature laser confocal microscope in-situ observation of the sample and crucible after the experiment is shown in the following photographs. Figure 8 As shown in the figure, the crucible without yttrium oxide coating undergoes a wetting reaction with the Ti-Cu alloy during heating, causing the interior of the alloy sample to rapidly cave in after melting, making it impossible to observe the microstructure evolution process after solidification. The real-time photograph of the in-situ microstructure evolution observed in this comparative example is shown below. Figure 9 As shown, no microstructure can be observed in the field of view of the high-temperature confocal microscope. This is because after the Ti alloy sample solidifies at high temperature, the liquid reacts completely with the crucible, causing internal depressions, so no microstructure can be observed in the field of view.

[0050] Comparative Example 2 This comparative example uses the same method as Example 1 for in-situ observation with a high-temperature laser confocal microscope. The difference is that step S3 is not performed, that is, no pure Ti wafer is suspended inside the furnace of the high-temperature laser confocal microscope.

[0051] In-situ observation using a high-temperature laser confocal microscope yielded the following comparative example images of the alloy sample surface observed in situ using this microscope: Figure 10 As shown, from Figure 10 As can be seen, there are oxide impurities on the sample surface, making it impossible to clearly observe the evolution process of the microstructure.

[0052] Comparative Example 3 This comparative example uses the same method as Example 1 for in-situ observation with a high-temperature laser confocal microscope. The difference is that step S2 is not performed, i.e., yttrium oxide powder is not sprayed on the surface of the alumina crucible.

[0053] In-situ observation using a high-temperature laser confocal microscope revealed that the microstructure of the solidified sample surface could not be observed. This is because the Ti-Cu alloy sample underwent a wetting reaction with the alumina crucible, resulting in a significant height difference on the sample surface.

[0054] Comparative Example 4 This comparative example uses the same method as Example 1 for in-situ observation using high-temperature laser confocal microscopy. The difference is that in step S2, the density of the sprayed coating is not controlled; that is, the operating current is controlled at 500A~700A and the operating voltage at 35V~75V throughout the process, and finally a 150μm thick layer of yttrium oxide powder is sprayed onto the surface of the alumina crucible. Images of the alloy sample surface observed in-situ using high-temperature laser confocal microscopy in this comparative example are shown below. Figure 11 As shown.

[0055] In-situ observation using a high-temperature laser confocal microscope revealed that the primary phase solidified in the liquid phase was clearly visible in the field of view. However, a small number of impurity particles were also present on the liquid phase surface, which affected the local observation results. This may be due to the poor density of the yttrium oxide coating applied in this embodiment and its insufficient bonding strength with the crucible substrate, causing some yttrium oxide powder to detach during heating and cooling. The detached powder may fall onto the sample surface under the influence of the furnace airflow, thus forming a small number of impurity particles on the liquid phase surface, thereby affecting the in-situ observation results.

[0056] Comparative Example 5 This comparative example uses the same method as Example 1 for in-situ observation with a high-temperature laser confocal microscope. The difference is that in step S2, during the spraying process, the thickness of the third layer is controlled to be 100 μm, which exceeds the range set by this invention. Finally, a layer of yttrium oxide powder with a thickness of 200 μm is sprayed on the surface of the alumina crucible.

[0057] In-situ observation using a high-temperature laser confocal microscope revealed that when 200 μm yttrium oxide powder was sprayed onto the surface of the alumina crucible, the yttrium oxide isolation layer was too thick. During high-temperature heating and cooling, it was prone to cracking or peeling due to thermal expansion mismatch and residual stress accumulation, thereby damaging the integrity of the isolation layer and potentially introducing additional temperature field disturbances. This was not conducive to the stable in-situ observation of the solidification process and microstructure of the Ti alloy.

[0058] Comparative Example 6 This comparative example uses the same method as Example 1 for in-situ observation with a high-temperature laser confocal microscope. The difference is that in step S2, the process of Example 1 is used to control the thickness of the first layer to be 30 μm, the thickness of the second layer to be 40 μm, and the thickness of the third layer to be 30 μm, so that a layer of yttrium oxide powder with a thickness of 100 μm is finally sprayed on the surface of the alumina crucible.

[0059] In-situ observation using a high-temperature laser confocal microscope revealed that a clear and complete field of view could not be found on the sample surface. This is because when 100 μm yttrium oxide powder was sprayed onto the surface of the alumina crucible, the yttrium oxide isolation coating was too thin, resulting in localized exposure. Consequently, a continuous and stable ceramic isolation interface could not be formed on the crucible surface, failing to effectively prevent direct contact between the Ti alloy and the alumina substrate.

[0060] Comparative Example 7 This comparative example uses the same method as Example 1 for in-situ observation with high-temperature laser confocal microscopy, except that in step S3, the flow rate of high-purity argon gas is 200 mL / min.

[0061] In-situ observations using a high-temperature laser confocal microscope revealed that it was difficult to precisely determine the exact location where the primary phase began to grow during the experiment, thus affecting the accurate assessment of the microstructure evolution process. This was mainly due to the excessive gas flow rate during the experiment. An excessive gas flow rate disturbs the surface of the melt micro-regions, causing significant fluctuations and undulations on the liquid surface. While these surface fluctuations occur, the primary phase may have already begun nucleation and growth, but its early growth process is easily masked by the surface fluctuations, increasing the difficulty of determining the nucleation location and the onset time of primary phase growth.

[0062] Comparative Example 8 This comparative example uses the same method as Example 1 for in-situ observation with high-temperature laser confocal microscopy, except that in step S3, the flow rate of high-purity argon gas is 70 mL / min.

[0063] In-situ observation using a high-temperature laser confocal microscope revealed difficulties in clearly observing the nucleation and early growth processes of the primary phase during the experiment. Analysis suggests that when the gas flow rate is too low, the gas circulation and replacement effects within the furnace are weak, resulting in poor local atmospheric stability. This can easily lead to slight oxidation or impurity accumulation on the sample surface, affecting the cleanliness of the melt surface. Under these conditions, the nucleation and early growth processes of the primary phase may be obscured by the surface oxide film or impurity particles, thus reducing the clarity of in-situ observation and affecting the accurate determination of the nucleation location and growth behavior of the primary phase.

[0064] Comparative Example 9 This comparative example uses the same method as Example 1 for in-situ observation with high-temperature laser confocal microscopy, except that in step S2, spherical yttrium oxide powder with a particle size of 60 μm is used.

[0065] In-situ observation using a high-temperature laser confocal microscope revealed that occasional particulate impurities appeared in the field of view during the experiment, interfering with the observation of primary phase nucleation and growth processes, thus affecting the accurate judgment of the microstructure evolution process. This is because, when using spherical yttrium oxide powder with a particle size of 50 μm, the larger yttrium oxide particles are not easily able to form a dense and uniform coating structure during spraying, and pores or weak bonding easily form between the particles. During heating and cooling, some particles may detach from the coating and enter the sample surface or the field of view under the action of gas, thus forming particulate impurities on the liquid phase surface, thereby affecting the in-situ observation effect.

[0066] Comparative Example 10 This comparative example uses the same method as Example 1 for in-situ observation with a high-temperature laser confocal microscope. The difference is that in step S3, the distance between the sample and the center of the pure Ti foil is 9 mm.

[0067] In-situ observation using a high-temperature laser confocal microscope revealed that occasional small impurities or localized oxidation occurred on the liquid phase surface during the experiment. These interferences hindered clear observation of the primary phase nucleation and growth process, thus affecting the accurate assessment of the microstructure evolution. This is because when the distance between the sample and the center of the pure Ti foil was 9 mm, the adsorption effect of the pure Ti foil on oxygen near the sample area was weakened, resulting in insufficient local atmosphere purification. Under high-temperature conditions, residual oxygen may react with the melt surface, forming a small amount of oxides or impurity particles, thereby affecting the cleanliness of the liquid phase surface and impacting the in-situ observation results.

[0068] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope, wherein the method is applied to Ti alloys with a Ti content of 53 at.% or higher, characterized in that... Includes the following steps: Pretreatment of S1 and Ti alloys: The Ti alloys are ground, polished, and ultrasonically cleaned. S2. Perform plasma spraying treatment on the alumina crucible, and spray a layer of yttrium oxide powder on its surface; S3. Suspend pure titanium sheets inside the furnace of a high-temperature laser confocal microscope; S4. Place the Ti alloy sample pretreated in step S1 into the crucible treated in step S2, and observe it in situ using a high-temperature laser confocal microscope.

2. The method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope according to claim 1, characterized in that, The Ti content in the Ti alloy is 53 at.% to 80 at.%.

3. The method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope according to claim 1, characterized in that, In step S1, the surface is polished until the roughness is less than 3μm.

4. The method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope according to claim 1, characterized in that, In step S1, polishing is performed using diamond polishing paste with a thickness of 0.25μm to 1.0μm.

5. The method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope according to claim 1, characterized in that, In step S2, the yttrium oxide powder is spherical yttrium oxide powder with a particle size of 35μm~50μm.

6. The method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope according to claim 1, characterized in that, In step S2, the powder feeding rate for plasma spraying is 30 g / min to 60 g / min, and the process includes: First layer: working current 500A~600A, working voltage 35V~45V, spraying thickness 30μm~50μm; Second layer: working current 650A~700A, working voltage 50V~75V, spraying thickness 50μm~70μm; The third layer has an operating current of 500A~600A, an operating voltage of 35V~45V, and a coating thickness of 30μm~60μm.

7. The method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope according to claim 1, characterized in that, In step S2, the plasma arc moving speed of the plasma spraying process is 70mm / s to 90mm / s, and the working distance is 90mm to 110mm.

8. The method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope according to claim 1, characterized in that, In step S2, the coating thickness is 130μm~180μm.

9. The method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope according to claim 1, characterized in that, In step S3, the pure titanium foil is 99.99% analytical grade.

10. The method for in-situ observation of Ti alloy samples using a high-temperature laser confocal microscope according to claim 1, characterized in that, In step S4, the flow rate of the inert gas during observation is 100 mL / min to 150 mL / min.

Images