A method of processing powder hot isostatically compacted titanium alloys in a vacuum environment

Abstract

The present application relates to the field of powder metallurgy, and specifically provides a vacuum environment treatment method for powder hot isostatic pressing titanium alloy.The treatment method comprises: S100, under the protection of inert atmosphere, mixing and treating titanium or titanium alloy matrix powder with hydrogenated powder to obtain mixed powder, filling the mixed powder in a container, and performing controllable dehydrogenation treatment on the container; S200, under the condition of no air exposure, placing the container treated in S100 into a hot isostatic pressing furnace, and performing hot isostatic pressing treatment to obtain a rough part; S300, performing vacuum dehydrogenation annealing treatment on the rough part to obtain the powder hot isostatic pressing titanium alloy.By introducing titanium hydride as an endogenous hydrogen source in the powder, and combining with the segmented controllable dehydrogenation, the stage pressurized hot isostatic pressing and the subsequent vacuum dehydrogenation annealing treatment, the present application can effectively improve the alloy density and microstructure uniformity, reduce internal porosity and inclusions, and thus improve the ductility and fatigue performance of the material.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy technology, and more specifically, it provides a vacuum environment treatment method for hot isostatic pressing of powder titanium alloys. Background Technology

[0002] Powder metallurgy and hot isostatic pressing (HIP) technology have become key processes for preparing high-performance titanium and titanium alloy components, widely used in aerospace, medical implants, and high-end manufacturing. Through the simultaneous action of powder densification and high temperature and pressure, HIP can achieve near-dense material microstructures and excellent mechanical properties, but it places high demands on powder pretreatment, furnace atmosphere control, and residual impurity content. The chemical purity and microstructure of the material directly determine the fatigue life, ductility, and service reliability of the final component; therefore, the gas behavior and removal strategies during the heating and densification process of the powder must be strictly designed and controlled.

[0003] To improve powder densification efficiency or enhance interfacial bonding between powder particles, existing technologies often employ the addition of hydride powder or hydrogenation processes as activation and reduction methods. The nascent hydrogen atoms released during the thermal decomposition of titanium hydride possess strong reducing properties, theoretically capable of reducing oxides on the powder surface, cleaning the surface, and thus improving sintering activity. However, this method faces significant challenges in practical industrial applications: the decomposition kinetics of hydrides are intense, releasing large amounts of hydrogen gas during heating. If the hydrogen release rate far exceeds the venting capacity of the vacuum system, or if it is mismatched with the timing of pressurized densification, closed pores can easily form inside the powder. This hydrogen gas, trapped under high pressure within the dense metal, may form a brittle hydride phase during subsequent cooling, or generate extremely high internal pressure, inducing hydrogen-induced cracks, leading to increased internal defects and a significant decrease in mechanical properties.

[0004] Therefore, there is an urgent need for a vacuum environment treatment method for powder hot isostatic pressing titanium alloys to meet the industrial requirements of high-performance titanium alloy parts. Summary of the Invention

[0005] This invention provides a vacuum environment treatment method for powder hot isostatic pressing titanium alloys. By introducing titanium hydride into the powder as an endogenous hydrogen source, and combining it with segmented controllable dehydrogenation, staged pressurized hot isostatic pressing, and subsequent vacuum dehydrogenation annealing, the density and microstructure uniformity of the alloy can be effectively improved, internal porosity and inclusions can be reduced, thereby improving the ductility and fatigue performance of the material.

[0006] This invention provides a vacuum environment treatment method for hot isostatic pressing (HIP) titanium alloy powder. The method includes the following steps: S100, under an inert atmosphere, titanium or titanium alloy matrix powder is mixed with hydrogenated powder to obtain a mixed powder, and the mixed powder is filled into a container, and the container is subjected to controlled dehydrogenation treatment; S200, under air-free conditions, the container treated in S100 is placed in a hot isostatic pressing furnace for hot isostatic pressing treatment to obtain a rough part; S300, the rough part is subjected to vacuum dehydrogenation annealing treatment to obtain a hot isostatic pressing titanium alloy powder.

[0007] In any of the above technical solutions, in step S100, the amount of hydrogenated powder added is 0.5-10 wt% of the total mass of the mixed powder, and the hydrogenated powder includes TiH2 or controllable hydrogenated alloy powder.

[0008] In any of the above technical solutions, in step S100, the controllable dehydrogenation process is carried out in a vacuum environment. The controllable dehydrogenation process includes a preheating section, an initial dehydrogenation section, and a low-speed exhaust section. The preheating section includes heating the container to 200-300°C at a rate of 5-20°C / min and holding it at that temperature for 30-60 min. The initial dehydrogenation section includes heating the container to 450-650°C at a rate of 5-20°C / min and holding it at that temperature for 30-180 min. The low-speed exhaust section includes maintaining a vacuum pressure of 0.1-1 Pa during the initial dehydrogenation section and subsequent cooling process.

[0009] In any of the above technical solutions, in the low-speed exhaust section, a residual gas analyzer is used to monitor the partial pressure of H2 and H2O. When the partial pressure of H2 drops below a predetermined threshold, it is determined that the controllable dehydrogenation process is complete, and the process proceeds to step S200.

[0010] In any of the above technical solutions, in step S100, an isolation layer is provided between the mixed powder and the inner wall of the container, and the isolation layer includes nickel foil or graphite sheet.

[0011] In any of the above technical solutions, in step S200, the hot isostatic pressing process adopts a staged pressurization strategy: an initial pressure is applied during the heating stage, and after the temperature rises to the dehydrogenation plateau and the H2 release rate is monitored to decrease, the pressure is then increased to the target final pressure.

[0012] In any of the above technical solutions, the initial pressure is 20-50 MPa, and the target final pressure is 100-200 MPa.

[0013] In any of the above technical solutions, in step S200, the temperature of hot isostatic pressing is 850-950℃ and the holding time is 1-4h.

[0014] In any of the above technical solutions, in step S300, the vacuum degree of the vacuum dehydrogenation annealing treatment is not higher than 0.1 Pa, the temperature is 500-750℃, and the holding time is 1-4 h.

[0015] In any of the above technical solutions, after the treatment in step S300, the residual hydrogen content of the powder hot isostatic pressing titanium alloy is not higher than 10 ppm.

[0016] The technical effects that can be achieved by adopting the technical solution of the present invention are as follows:

[0017] (1) By introducing the synergistic effect of endogenous hydrogen source and segmented controllable dehydrogenation, efficient in-situ reduction and activation of oxides on powder surface were achieved, which significantly improved the densification efficiency and density of subsequent hot isostatic pressing.

[0018] (2) By combining staged pressurized HIP with final vacuum dehydrogenation annealing, the problem of high residual hydrogen content was effectively solved, and the hydrogen content was stably controlled below 10ppm, avoiding hydrogen-induced defects and significantly improving the ductility and fatigue performance of the material.

[0019] (3) Setting an isolation layer between the container and the powder can physically isolate the container metal from direct contact with the powder, reduce the diffusion of container materials and chemical pollution, reduce interface inclusions and adhesion, facilitate demolding and improve the reusability and production stability of the container.

[0020] (4) The present invention successfully integrates powder pretreatment, activation, degassing, densification and final heat treatment into one process. The entire process is completed under vacuum or inert atmosphere protection. The final titanium alloy component has ultra-high density, ultra-low impurity content and excellent comprehensive mechanical properties, which is a significant improvement compared with traditional processes. Detailed Implementation

[0021] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0022] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0023] To make the above-mentioned objectives, features and advantages of this aspect more apparent and understandable, specific embodiments of this aspect are described in detail below.

[0024] Current powder hot isostatic pressing (POP) techniques for preparing titanium alloys generally face challenges such as internal porosity, hydrogen embrittlement, and performance degradation due to uncontrollable hydrogen release during the hydrogen removal process and asynchronous degassing and densification. Furthermore, the residual hydrogen content is difficult to stably reduce to the ppm level, severely restricting the consistency and production efficiency of high-performance titanium alloy components. Therefore, there is an urgent need to develop a closed-loop process method that can achieve controlled hydrogen release, efficient hydrogen removal, and simultaneous densification.

[0025] In view of this, this embodiment provides a vacuum environment treatment method for powder hot isostatic pressing titanium alloys, the method including the following steps:

[0026] S100. Under an inert atmosphere, titanium or titanium alloy matrix powder is mixed with hydrogenated powder to obtain mixed powder. The mixed powder is then filled into a container, and the container is subjected to controlled dehydrogenation treatment.

[0027] S200: Under conditions of no air exposure, the container treated by S100 is placed in a hot isostatic pressing furnace for hot isostatic pressing to obtain a rough part.

[0028] S300: Vacuum dehydrogenation annealing is performed on the rough parts to obtain powder hot isostatic pressing titanium alloy.

[0029] Preferably, in step S100, the hydrogenated powder decomposes and releases hydrogen gas during heating, taking TiH2 as an example:

[0030] TiH2→Ti+H2↑.

[0031] In the controlled dehydrogenation process, the active hydrogen released from the decomposition of titanium hydride is distributed in gaseous form among the powder particles. This hydrogen reacts with and desorbs adsorbed water, hydroxyl groups, and organic contaminants on the titanium powder surface, while simultaneously reducing the thin layer of titanium oxide and suboxides on the surface to generate volatile water vapor. This process effectively cleans the powder surface, exposing a fresh, highly active metal interface. This cleaned and hydrogen-activated surface significantly promotes metal bonding, atomic interdiffusion, and sintering neck growth between powder particles, providing crucial interfacial conditions for subsequent densification processes. Simultaneously, the hydrogen release generates a transient gas-phase driving force in the pore network, which, combined with vacuum or inert gas replacement pulses, effectively removes adsorbed gases and generated volatiles. Overall, this step significantly improves powder surface cleanliness and activity, promotes densification, and reduces unclosed pores and interfacial inclusions, thereby achieving higher density and more uniform microstructure under the same or milder temperature and pressure conditions, ultimately improving the material's ductility, fatigue life, and reliability. Compared with the method of directly introducing a large amount of external reducing gas, the process using an endogenous hydrogen source is more flexible and industrially friendly, and it is easy to achieve continuous operation in a closed container. However, it is necessary to control hydrogen release and discharge in stages to avoid porosity or hydrogen-related defects caused by rapid hydrogen release.

[0032] Furthermore, in step S100, the amount of hydrogenated powder added is 0.5-10 wt% of the total mass of the mixed powder, and the hydrogenated powder includes TiH2 or controllable hydrogenation alloy powder. If the amount of hydrogenated powder added is less than 0.5 wt%, the resulting reducing atmosphere is insufficient to effectively clean all powder surfaces, resulting in a negligible effect; if the amount of hydrogenated powder added is greater than 10 wt%, excessive hydrogen gas will be released, making it difficult to completely avoid the risk of closed-cell formation even with staged dehydrogenation, and increasing the difficulty of process control and the burden of dehydrogenation annealing. TiH2 is the most commonly used and economical hydrogen source. Controllable hydrogenation alloy powder refers to hydrogenated powder of other titanium alloys; using them can avoid the introduction of additional types of metal elements, making them particularly suitable for applications with extremely high requirements for composition control.

[0033] Furthermore, in step S100, the controlled dehydrogenation treatment is carried out under vacuum. The controlled dehydrogenation treatment includes a preheating section, an initial dehydrogenation section, and a low-speed exhaust section. The preheating section involves heating the container to 200-300°C at a rate of 5-20°C / min and holding it at that temperature for 30-60 minutes to remove surface-adsorbed moisture, volatile organic compounds, and weakly bound adsorbed gases, thereby reducing the initial volatile load of the system. The initial dehydrogenation section involves heating the container to 450-650°C at a rate of 5-20°C / min and... The process involves holding the hydrogenated powder at a temperature of 30-180 min, covering the hydride decomposition temperature range. This allows for the phased decomposition of the hydrogenated powder and the controlled release of H2, ensuring that the released hydrogen is effectively replaced or extracted at lower temperatures and pressures, while simultaneously partially reducing surface oxides. The low-speed exhaust stage, including the initial dehydrogenation stage and subsequent cooling process, maintains a vacuum pressure of 0.1-1 Pa. Maintaining low-speed exhaust prevents sudden pressure spikes and gas blockage, thus preventing the formation of closed pores or hydrogen-induced defects during the subsequent pressurization densification stage. This phased, controllable dehydrogenation process achieves a match between the time and rate of hydrogen release and exhaust, cleans and activates the powder surface, reduces interfacial oxygen content, avoids gas blockage during high-pressure densification, significantly improves the efficiency and density of subsequent hot isostatic pressing densification, improves microstructure uniformity, and helps reduce residual hydrogen to the ppm level, thereby improving the material's ductility, fatigue performance, and reliability.

[0034] Furthermore, during the low-speed exhaust stage, a residual gas analyzer is used to monitor the partial pressures of H2 and H2O within the chamber in real time, providing a clear quantitative endpoint criterion for the controllable dehydrogenation process. Preferably, when the H2 partial pressure is detected to decrease and stabilize at a predetermined threshold, and the H2 / H2O ratio reaches or exceeds the expected range, it is determined that the dehydrogenation replacement process is essentially complete, thus safely proceeding to the subsequent staged pressurization or vacuum annealing steps. When the H2 partial pressure within the chamber drops to this level, it indicates that the free hydrogen released by the decomposition of the hydrogenated powder has been effectively replaced, extracted, or chemically captured, and the residual defective hydrogen content in the chamber atmosphere is extremely low, significantly reducing the risk of continued densification under high pressure. Preferably, using H2 partial pressure ≤ 0.01 Pa as the quantitative endpoint for controllable dehydrogenation, and using residual gas analysis and time stability criteria as triggering conditions, can significantly reduce the probability of closed pores and hydrogen-induced defects during high-pressure densification, which is beneficial for obtaining higher relative density, more uniform microstructure, and better fatigue and ductility properties. At the same time, this judgment logic facilitates automated control and data recording, providing quantifiable control points and acceptance criteria for process scale-up and quality assurance.

[0035] Preferably, in step S100, an isolation layer is provided between the mixed powder and the inner wall of the container. The isolation layer includes nickel foil or graphite sheets. The isolation layer physically cuts off the direct contact between the powder and the container metal, significantly reducing the risk of the container material diffusing into the powder or reacting chemically with the powder, thereby preventing the inner wall from contaminating the powder and reducing interface inclusions. The isolation layer also serves as a mechanical and thermal stress buffer layer, reducing adhesion and cold bonding during hot isostatic pressing and heating-cooling processes, facilitating demolding and container reuse. In addition, the container is usually made of steel. At high temperatures, iron elements diffuse into the titanium powder, forming brittle Fe-Ti intermetallic compounds, which become fatigue crack initiation sources. The isolation layer acts as a diffusion barrier. Specifically, nickel foil, with its excellent high-temperature strength and airtightness, is suitable as a metal isolation layer, providing robust chemical and mechanical protection for the powder under high-temperature vacuum or inert atmospheres, and does not react violently with titanium. Graphite sheets, due to their solid lubricity, good high-temperature gas conduction channels, and thermal shock mitigation properties, are beneficial for the extraction and replacement of gas within the pores and reduce local stress concentration. In summary, the isolation layer reduces container-powder chemical contamination and interdiffusion, improves the cleanliness of the powder surface and densification process, reduces the difficulty of adhesion and disassembly, and improves heat conduction and venting conditions, thereby contributing to higher density, fewer inclusions / defects, and more uniform microstructure and mechanical properties.

[0036] Preferably, in step S200, the container treated in S100 is directly placed into a hot isostatic pressing furnace under air-free conditions for hot isostatic pressing treatment. This maintains the surface activation and low oxygen / low adsorbed gas state of the powder obtained during the controlled dehydrogenation stage. In a closed, controlled temperature-pressure field, the powder particles undergo plastic flow, neck growth, and diffusion bonding driven by isothermal high pressure, thereby closing pores and eliminating interconnected pore networks. In particular, the use of staged pressurization allows for matching hydrogen release with pressurization timing, preventing the closure of unexpelled gas under high pressure, which could lead to closed pores or hydrogen-induced defects. Simultaneously, high pressure promotes the dissolution and diffusion of residual gas in the pores. This maintains the cleanliness of the powder surface and a low oxygen content state, facilitating interface welding, significantly improving densification efficiency and relative density, reducing residual pores and inclusions, and improving microstructure uniformity and mechanical properties. Furthermore, it reduces the burden of subsequent processing and vacuum annealing, improves product consistency and yield, and reduces the risk of oxidation, combustion, or contamination of the powder during transfer, thus contributing to the controllability and safety of industrial production. In addition, the powder container treated by S100 is in an activated state with clean surface, low oxygen content and few adsorbed gases. It is directly fed into the HIP furnace under no air exposure conditions, avoiding secondary oxidation of the powder due to contact with air during the transfer process.

[0037] Furthermore, the hot isostatic pressing (HIP) process employs a staged pressurization strategy: an initial pressure is applied during the heating stage, and once the temperature reaches the dehydrogenation plateau and the H2 release rate decreases, the pressure is increased to the target final pressure. Specifically, a relatively low initial pressure, preferably 20-50 MPa, is applied during the heating stage. The purpose is not to immediately achieve densification, but rather to apply a moderate pre-compacting force. This pre-compacting force is sufficient to induce preliminary plastic deformation and rearrangement of the loose powder particles, establishing a mechanical framework of mutual contact and an interconnected pore network, but not enough to prematurely crush and close the tiny channels between particles. Under this low initial pressure, hydrogen released from the decomposition of hydrogenated powder within the powder, as well as other volatile gases desorbed from the powder surface, can efficiently escape from the powder along these interconnected channels with low resistance due to their own partial pressure and the suction effect of the system vacuum, and are continuously removed by the furnace's vacuum system. This effectively avoids the risk of gases being trapped inside the powder under high pressure during the initial densification stage due to insufficient time for expulsion. When the furnace temperature rises to the late stage of the main decomposition plateau of hydrides or higher, and the H2 release rate is significantly reduced and stabilized as monitored by the integrated residual gas analyzer, it indicates that the main gas release process inside the powder has been basically completed, and the powder surface has been fully activated and cleaned by the reduction of active hydrogen. At this point, the pressure is then steadily increased to the target final pressure under programmed control, preferably 100-200 MPa. In this stage, the powder particles are in a high-temperature state, with a sharp increase in plasticity, and the surface is clean and activated, possessing excellent diffusion and bonding conditions. The application of ultra-high hydrostatic pressure will efficiently drive significant plastic flow of the powder particles, accelerate grain boundary diffusion and bulk diffusion processes, rapidly form strong sintering necks at the previously established interparticle contact points, and ultimately rapidly crush, shrink, and eliminate the remaining isolated pores, thereby achieving complete densification of the material.

[0038] Furthermore, the hot isostatic pressing (HIP) treatment is carried out at temperatures of 850-950℃ and a holding time of 1-4 hours. The high temperature provides sufficient atomic diffusion energy and driving force for the growth of neck length between powder particles, enabling rapid diffusion bonding and plastic flow after the powder surface is activated. The appropriate holding time ensures sufficient interface welding and homogenization of composition and temperature field, while avoiding incomplete densification due to excessively short holding time or excessive grain growth due to excessively long holding time. When combined with the staged hydrogen release and staged pressurization strategy, this set of thermo-pressurization timelines can both steadily increase the final pressure to complete densification after the hydrogen release rate decreases, and minimize closed pores and retain a surface state with low oxygen content and low residual hydrogen, thereby significantly improving relative density, uniform microstructure, and the ductility and fatigue properties of the material, while reducing the burden of subsequent vacuum dehydrogenation annealing.

[0039] Preferably, in step S300, the vacuum degree of the vacuum dehydrogenation annealing treatment is no higher than 0.1 Pa, the temperature is 500-750℃, and the holding time is 1-4 h. The vacuum provides a strong pressure gradient and an oxidation-free environment, promoting the escape and removal of hydrogen from the powder in gaseous form. The suitable temperature can significantly improve the diffusion rate of hydrogen in the α / β titanium phase and grain boundaries, accelerate the decomposition of metal hydrides, and is below the limit temperature that would cause severe grain growth, thus maintaining a refined microstructure while efficiently dehydrogenating. The appropriate holding time ensures that the gradient of hydrogen concentration in the bulk is flattened and fully diffused out, reducing residual hydrogen to the ppm level and promoting the recovery of lattice stress and substructure. In summary, it can effectively dissolve and remove residual hydrogen and hydrides, reduce the risk of hydrogen embrittlement, eliminate internal stress, and homogenize the microstructure, thereby significantly improving the ductility, fatigue performance, and service reliability of the material, while avoiding performance degradation caused by over-annealing.

[0040] Furthermore, the residual hydrogen content of powder hot isostatic pressing titanium alloys is no higher than 10 ppm, which can significantly reduce the risk of hydride precipitation and hydrogen embrittlement, and avoid microcracks or delayed fracture caused by local hydrogen enrichment. Therefore, the ductility, fracture toughness and fatigue life of the material will be significantly improved, while the consistency and repeatability of mechanical properties will be improved, reducing performance fluctuations between batches. Low residual hydrogen is also beneficial to avoid crack sensitivity and dimensional stability problems during subsequent processing, thereby improving the service reliability and applicability of components and meeting the long-term service standards of high-requirement applications such as aerospace.

[0041] Furthermore, even after steps S100 and S200, trace amounts of hydrogen may still remain inside the material. Step S300 serves as a safety and optimization step; annealing under high vacuum and at an appropriate temperature provides the final conditions for the diffusion and escape of residual hydrogen, ensuring that the residual hydrogen content of the final product remains consistently below the stringent standard of 10 ppm. Simultaneously, this annealing process also helps eliminate internal stresses generated during the HIP process, homogenizes the microstructure, and further stabilizes and optimizes the overall mechanical properties of the material.

[0042] In summary, this embodiment successfully solved several key problems in powder metallurgy titanium alloys, such as densification, impurity removal, and microstructure homogenization, through the synergistic effect of steps S100, S200, and S300. The titanium alloy components finally prepared have high density, low impurity content, and excellent mechanical properties.

[0043] Example 1

[0044] This embodiment provides a vacuum environment treatment method for powder hot isostatic pressing titanium alloys, the method including the following steps:

[0045] S100. Under the protection of argon atmosphere, titanium alloy matrix powder is mixed with 5wt% TiH2 to obtain mixed powder. The mixed powder is then filled into a container with a nickel foil isolation layer, and the container is subjected to controlled dehydrogenation treatment in a vacuum environment. The preheating stage includes heating the container to 250℃ at a rate of 10℃ / min and holding it at that temperature for 45min. The initial dehydrogenation stage includes heating the container to 500℃ at a rate of 10℃ / min and holding it at that temperature for 90min. The low-speed exhaust stage includes maintaining the vacuum pressure at 0.5Pa during the initial dehydrogenation stage and subsequent cooling process. The partial pressures of H2 and H2O are monitored using a residual gas analyzer. When the partial pressure of H2 is ≤0.01Pa, the controlled dehydrogenation treatment is determined to be complete, and the process proceeds to step S200.

[0046] S200. Under conditions of no air exposure, the container treated by S100 is placed in a hot isostatic pressing furnace for hot isostatic pressing. The hot isostatic pressing process adopts a staged pressurization strategy: 35MPa is applied during the heating stage. After the temperature rises to 900℃ and the H2 release rate is monitored to decrease, the pressure is increased to 150MPa and held for 2 hours to obtain the rough part.

[0047] S300. Under air-free conditions, the rough parts are transferred from the container and placed in a vacuum annealing furnace. Vacuum dehydrogenation annealing is performed at a vacuum degree not exceeding 0.1 Pa, a temperature of 600 °C, and a holding time of 2 h to obtain powder hot isostatic pressing titanium alloy.

[0048] Example 2

[0049] This embodiment provides a vacuum environment treatment method for powder hot isostatic pressing titanium alloys, the method including the following steps:

[0050] S100. Under the protection of argon atmosphere, pure titanium powder is mixed with 0.5 wt% of controllable hydrogenation alloy powder to obtain a mixed powder. The mixed powder is then filled into a container with a graphite sheet isolation layer, and the container is subjected to controllable dehydrogenation treatment in a vacuum environment. The preheating stage includes heating the container to 200°C at a rate of 5°C / min and holding it at that temperature for 60 min. The initial dehydrogenation stage includes heating the container to 450°C at a rate of 5°C / min and holding it at that temperature for 180 min. The low-speed exhaust stage includes maintaining a vacuum pressure of 0.1 Pa during the initial dehydrogenation stage and subsequent cooling process. The partial pressures of H2 and H2O are monitored using a residual gas analyzer. When the partial pressure of H2 is ≤0.01 Pa, the controllable dehydrogenation treatment is determined to be complete, and the process proceeds to step S200.

[0051] S200. Under conditions of no air exposure, the container treated by S100 is placed in a hot isostatic pressing furnace for hot isostatic pressing treatment. The hot isostatic pressing treatment adopts a staged pressurization strategy: 20MPa is applied during the heating stage. After the temperature rises to 850℃ and the H2 release rate is monitored to decrease, the pressure is increased to 100MPa and held for 4 hours to obtain the rough part.

[0052] S300. Under air-free conditions, the rough parts are transferred from the container and placed in a vacuum annealing furnace. Vacuum dehydrogenation annealing is performed at a vacuum degree not exceeding 0.1 Pa, a temperature of 500 °C, and a holding time of 4 h to obtain powder hot isostatic pressing titanium alloy.

[0053] Example 3

[0054] This embodiment provides a vacuum environment treatment method for powder hot isostatic pressing titanium alloys, the method including the following steps:

[0055] S100. Under the protection of argon atmosphere, titanium alloy matrix powder is mixed with 10wt% TiH2 to obtain mixed powder. The mixed powder is then filled into a container with a nickel foil isolation layer, and the container is subjected to controlled dehydrogenation treatment in a vacuum environment. The preheating stage includes heating the container to 300℃ at a rate of 20℃ / min and holding it at that temperature for 30min. The initial dehydrogenation stage includes heating to 650℃ at a rate of 20℃ / min and holding it at that temperature for 30min. The low-speed exhaust stage includes maintaining a vacuum pressure of 1Pa during the initial dehydrogenation stage and subsequent cooling process. The partial pressures of H2 and H2O are monitored using a residual gas analyzer. When the partial pressure of H2 is ≤0.01Pa, the controlled dehydrogenation treatment is determined to be completed, and the process proceeds to step S200.

[0056] S200. Under conditions of no air exposure, the container treated by S100 is placed in a hot isostatic pressing furnace for hot isostatic pressing. The hot isostatic pressing process adopts a staged pressurization strategy: 50MPa is applied during the heating stage. After the temperature rises to 950℃ and the H2 release rate is monitored to decrease, the pressure is increased to 200MPa and held for 1 hour to obtain the rough part.

[0057] S300. Under air-free conditions, the rough parts are transferred from the container and placed in a vacuum annealing furnace. Vacuum dehydrogenation annealing is performed at a vacuum degree not exceeding 0.1 Pa, a temperature of 750 °C, and a holding time of 1 h to obtain powder hot isostatic pressing titanium alloy.

[0058] Example 4

[0059] This embodiment provides a vacuum environment treatment method for powder hot isostatic pressing titanium alloys, the method including the following steps:

[0060] S100. Under the protection of argon atmosphere, titanium alloy matrix powder is mixed with 8wt% TiH2 to obtain mixed powder. The mixed powder is then filled into a container with a nickel foil isolation layer, and the container is subjected to controlled dehydrogenation treatment in a vacuum environment. The preheating stage includes heating the container to 280℃ at a rate of 18℃ / min and holding it at that temperature for 40min. The initial dehydrogenation stage includes heating the container to 630℃ at a rate of 18℃ / min and holding it at that temperature for 40min. The low-speed exhaust stage includes maintaining a vacuum pressure of 1Pa during the initial dehydrogenation stage and subsequent cooling process. The partial pressures of H2 and H2O are monitored using a residual gas analyzer. When the partial pressure of H2 is ≤0.01Pa, the controlled dehydrogenation treatment is determined to be completed, and the process proceeds to step S200.

[0061] S200. Under conditions of no air exposure, the container treated by S100 is placed in a hot isostatic pressing furnace for hot isostatic pressing. The hot isostatic pressing process adopts a staged pressurization strategy: 40MPa is applied during the heating stage. After the temperature rises to 950℃ and the H2 release rate is monitored to decrease, the pressure is increased to 180MPa and held for 2 hours to obtain the rough part.

[0062] S300. Under air-free conditions, the rough parts are transferred from the container and placed in a vacuum annealing furnace. Vacuum dehydrogenation annealing is performed at a vacuum degree not exceeding 0.1 Pa, a temperature of 700 °C, and a holding time of 1 h to obtain powder hot isostatic pressing titanium alloy.

[0063] Example 5

[0064] This embodiment provides a vacuum environment treatment method for powder hot isostatic pressing titanium alloys, the method including the following steps:

[0065] S100. Under an argon atmosphere, pure titanium powder is mixed with 2.5 wt% of controllable hydrogenation alloy powder to obtain a mixed powder. The mixed powder is then filled into a container with a graphite sheet isolation layer, and the container is subjected to controllable dehydrogenation treatment under vacuum. The preheating stage includes heating the container to 220°C at a rate of 8°C / min and holding it at that temperature for 50 min. The initial dehydrogenation stage includes heating the container to 480°C at a rate of 8°C / min and holding it at that temperature for 100 min. The low-speed exhaust stage includes maintaining a vacuum pressure of 0.1 Pa during the initial dehydrogenation stage and subsequent cooling process. The partial pressures of H2 and H2O are monitored using a residual gas analyzer. When the partial pressure of H2 is ≤0.01 Pa, the controllable dehydrogenation treatment is considered complete, and the process proceeds to step S200.

[0066] S200. Under conditions of no air exposure, the container treated by S100 is placed in a hot isostatic pressing furnace for hot isostatic pressing. The hot isostatic pressing process adopts a staged pressurization strategy: 30MPa is applied during the heating stage. After the temperature rises to 850℃ and the H2 release rate is monitored to decrease, the pressure is increased to 120MPa and held for 3 hours to obtain the rough part.

[0067] S300. Under air-free conditions, the rough parts are transferred from the container and placed in a vacuum annealing furnace. Vacuum dehydrogenation annealing is performed at a vacuum degree not exceeding 0.1 Pa, a temperature of 520°C, and a holding time of 3 hours to obtain powder hot isostatic pressing titanium alloy.

[0068] Comparative Example 1

[0069] This embodiment provides a powder hot isostatic pressing titanium alloy, which adopts the conventional HIP process, i.e., without the addition of an endogenous hydrogen source and segmented dehydrogenation control.

[0070] Test data

[0071] The powder hot isostatic pressing titanium alloy samples obtained in Examples 1-5 and Comparative Example 1 were subjected to the following performance tests;

[0072] (1) Density test: The Archimedes water displacement method was used to determine the density of dense sintered metal materials and cemented carbide according to GB / T3850-2015. The results are shown in Table 1.

[0073] (2) Determination of residual hydrogen content: The inert gas melting-thermal conductivity method was used to determine the hydrogen content according to GB / T4698.15-2011 "Determination of hydrogen content in titanium and titanium alloys by chemical analysis method". The results are shown in Table 1.

[0074] (3) Room temperature tensile properties test: Standard tensile specimens were processed and tested according to GB / T228.1-2021 "Metallic materials - Tensile testing - Part 1: Room temperature test method", and the results are shown in Table 1.

[0075] (4) Microhardness test: The test was conducted in accordance with GB / T4340.1-2009 "Metallic materials Vickers hardness test - Part 1: Test method", and the results are shown in Table 1.

[0076] Table 1

[0077]

[0078] As can be seen from the test data in Table 1, all five embodiments of the present invention achieved excellent comprehensive performance under the synergistic process of controllable hydride addition, segmented controllable dehydrogenation, and staged pressurization.

[0079] Density: The density of all embodiments of the present invention is higher than 99.5%, which is significantly higher than 98.5% of Comparative Example 1, demonstrating the excellent effect of the process of the present invention in eliminating porosity.

[0080] Residual hydrogen content: The hydrogen content in all embodiments of the present invention is far below the aviation standard of 10 ppm, while Comparative Example 1 is as high as 45 ppm, which poses a serious risk of hydrogen embrittlement.

[0081] Mechanical properties: The strength, hardness, and especially the elongation after fracture of the embodiments of the present invention are all superior to those of Comparative Example 1. The significant improvement in elongation after fracture fully demonstrates the advantages of the present invention in reducing defects and improving interface.

[0082] In summary, this invention, through a systematic vacuum environment treatment method and process parameter control, achieves increased relative density, reduced residual hydrogen, and improved tensile strength and elongation after fracture. This demonstrates that the process of this invention effectively reduces internal porosity and hydrogen-related defects, improves microstructure uniformity, and significantly enhances the ductility and strength of the material. The comprehensive test results support the technical feasibility and superiority of this invention in preparing high-density, high-reliability powder hot isostatic pressing titanium alloy components.

[0083] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0084] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for vacuum environment treatment of powder hot isostatic pressing titanium alloy, characterized in that, The processing method includes the following steps: S100. Under an inert atmosphere, titanium or titanium alloy matrix powder is mixed with hydrogenated powder to obtain a mixed powder. The mixed powder is then filled into a container, and the container is subjected to controlled dehydrogenation treatment. S200: Under conditions of no air exposure, the container treated by S100 is placed in a hot isostatic pressing furnace for hot isostatic pressing to obtain a rough part. S300. The rough part is subjected to vacuum dehydrogenation annealing to obtain the powder hot isostatic pressing titanium alloy. In step S100, the amount of hydrogenated powder added is 0.5-10 wt% of the total mass of the mixed powder, and the hydrogenated powder includes TiH2 or controllable hydrogenated alloy powder. The controlled dehydrogenation process is carried out in a vacuum environment and includes a preheating section, an initial dehydrogenation section, and a low-speed exhaust section. The preheating section includes heating the container to 200-300°C at a rate of 5-20°C / min and holding it at that temperature for 30-60min; The initial dehydrogenation section includes heating to 450-650°C at a rate of 5-20°C / min and holding at that temperature for 30-180min; The low-speed exhaust section includes a vacuum maintained at a pressure of 0.1-1 Pa during the initial dehydrogenation section and subsequent cooling process; In the low-speed exhaust section, a residual gas analyzer is used to monitor the partial pressure of H2 and H2O in the chamber. When the partial pressure of H2 drops below a predetermined threshold, the controllable dehydrogenation process is determined to be complete, and the process proceeds to step S200. In step S100, an isolation layer is provided between the mixed powder and the inner wall of the container, the isolation layer comprising nickel foil or graphite sheet; In step S200, the hot isostatic pressing process adopts a staged pressurization strategy: an initial pressure is applied during the heating stage, and after the temperature rises to the dehydrogenation plateau and the H2 release rate is monitored to decrease, the pressure is then increased to the target final pressure; the initial pressure is 20-50 MPa, and the target final pressure is 100-200 MPa.

2. The method according to claim 1, characterized in that, In step S200, the hot isostatic pressing treatment is performed at a temperature of 850-950℃ and for a holding time of 1-4 hours.

3. The method according to claim 1, characterized in that, In step S300, the vacuum degree of the vacuum dehydrogenation annealing treatment is not higher than 0.1 Pa, the temperature is 500-750℃, and the holding time is 1-4 h.

4. The method according to claim 1, characterized in that, After the treatment in step S300, the residual hydrogen content of the powder hot isostatic pressing titanium alloy is not higher than 10 ppm.

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