Method for increasing oxygen in titanium alloy

Abstract

The application relates to the field of titanium alloy preparation and discloses a method for increasing oxygen in a titanium alloy, which comprises the following steps: adding target additives into titanium tetrachloride and uniformly mixing to obtain a mixture; wherein the target additives at least include chlorides containing target alloy elements and oxygen elements; adding the mixture into liquid magnesium to carry out a reduction reaction to obtain a reaction product containing a titanium alloy; and carrying out separation treatment on the reaction product to obtain an oxygen-increased titanium alloy product. The application can realize uniform distribution of oxygen elements in the titanium alloy product and can realize no oxide inclusion defects, so that the mechanical properties of the titanium alloy are improved; and the alloy elements and the oxygen elements can be added cooperatively, so that the process flow is simplified.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy preparation technology, and specifically to a method for oxygenating titanium alloys. Background Technology

[0002] Titanium and titanium alloys are widely used in aerospace, shipbuilding, chemical, and medical fields due to their excellent properties such as high specific strength, good corrosion resistance, and high temperature resistance. Oxygen is an important interstitial element in titanium alloys, significantly affecting their mechanical properties. Studies have shown that when oxygen forms an interstitial solid solution in titanium, it can produce a strong solid solution strengthening effect, significantly improving the strength and hardness of titanium alloys. Currently, the industrial production of titanium and titanium alloys mainly uses the Kroll process, which involves the magnesothermic reduction of titanium tetrachloride to prepare sponge titanium, followed by mixing the sponge titanium with alloying elements and then processing it through processes such as vacuum arc melting to produce titanium alloys. In traditional titanium alloy oxidation processes, TiO2 powder is usually added to the sponge titanium as an oxygenating agent during the melting stage, and the oxidation of the titanium alloy is achieved through processes such as mixing, electrode pressing, and melting.

[0003] However, the traditional oxygenation method has the following technical problems: (1) Uneven oxygen distribution: Due to the large difference in density and morphology between TiO2 powder and sponge titanium, it is difficult to achieve uniform mixing during the mixing process, which easily leads to local segregation of TiO2 powder, resulting in uneven distribution of oxygen content in titanium alloy and forming oxygen segregation; (2) Oxide inclusion defects: If TiO2 powder fails to completely decompose and diffuse during the melting process, it will form oxide inclusions in the titanium alloy matrix. These inclusions not only affect the mechanical properties of the alloy, but may also become crack sources, reducing the fatigue performance and toughness of the titanium alloy; (3) Difficulty in process control: The traditional method requires precise control of the amount of TiO2 powder added, particle size and melting process parameters to ensure that the oxide is fully decomposed and oxygen is diffused uniformly. The process control is difficult and the product quality stability is poor.

[0004] Patent CN102978441A discloses a method for co-adding oxygen and iron to titanium alloys. This method incorporates oxygen and iron elements in the form of mixed powders to oxygenate the titanium material during the smelting process. However, due to the poor adhesion of the powdered oxygenating agent to the surface of sponge titanium, there are still problems such as easy local segregation and uneven oxygen distribution.

[0005] Patent CN119392007A discloses a method for producing high oxygen content sponge titanium, which uses titanium dichloride solution as an oxygenating agent and mixes it with purified titanium tetrachloride. However, this method is only for oxygenating pure sponge titanium, and the type of oxygenating agent is limited. It cannot simultaneously achieve the synergistic addition of multiple alloying elements and oxygen elements, making it difficult to meet the preparation requirements of complex titanium alloys.

[0006] Therefore, developing a titanium alloy oxygenation improvement method that can achieve uniform oxygen distribution, no oxide inclusions, and simple and controllable process is of great significance for improving the performance of titanium alloys and expanding their application range. Summary of the Invention

[0007] The main objective of this invention is to provide a method for oxygenating titanium alloys, so as to solve the problems of uneven oxygen distribution, oxide inclusion defects, and difficulty in process control in existing titanium alloy oxygenation technologies.

[0008] According to one aspect of the present invention, a method for oxygenating a titanium alloy is provided, comprising the following steps: S1, adding a target additive to titanium tetrachloride and mixing it uniformly to obtain a mixture; wherein the target additive includes at least a chloride containing a target alloying element and an oxygen element; S2, adding the mixture to liquid magnesium for a reduction reaction to obtain a reaction product containing a titanium alloy; S3, separating the reaction product to obtain an oxygenated titanium alloy product.

[0009] According to one embodiment of the present invention, in step S1, the chloride containing the target alloying element and oxygen element includes at least one of VOCl3 and AlOCl.

[0010] According to one embodiment of the present invention, in step S1, the additive further includes at least one of a chloride and a non-chloride oxygen source containing the target alloying element and free of oxygen.

[0011] According to one embodiment of the present invention, in step S1, the chloride containing the target alloying element and not containing oxygen includes AlCl3, and the non-chloride oxygen source includes H2O.

[0012] According to one embodiment of the present invention, in step S1, the amount of the target additive added is such that the oxygen content of the titanium alloy product is 0.1 to 1.5 wt%.

[0013] According to one embodiment of the present invention, in step S1, uniform mixing is achieved by stirring for 30 to 120 minutes at a stirring speed of 50 to 200 rpm.

[0014] According to one embodiment of the present invention, in step S2, the mixture is added to liquid magnesium in gaseous form.

[0015] According to one embodiment of the present invention, in step S2, the mixture is added to liquid magnesium at 660-900°C; the temperature of the reduction reaction is 750-850°C, and the reaction time is 8-24 hours.

[0016] According to one embodiment of the present invention, in step S2, the reduction reaction is carried out in an inert protective atmosphere.

[0017] According to one embodiment of the present invention, in step S3, the separation process includes performing vacuum distillation to separate MgCl2 and metallic magnesium from the reaction product; the temperature of vacuum distillation is 900-1100°C, the vacuum degree is ≤10Pa, and the distillation time is 20-60 hours.

[0018] In the technical solution of this invention, a target additive comprising at least a chloride containing the target alloying element and oxygen is added to titanium tetrachloride. Utilizing the good miscibility of this type of chloride with titanium tetrachloride in the liquid state, uniform mixing of the target additive and titanium tetrachloride at the molecular level is achieved, ensuring uniform dispersion of oxygen in the titanium matrix after the reduction reaction. The resulting mixture is then added to liquid magnesium for a reduction reaction, allowing the chloride containing the target alloying element and oxygen to be simultaneously reduced by magnesium along with the titanium tetrachloride. Oxygen directly enters the titanium lattice to form a uniform interstitial solid solution without oxide inclusions, while the target alloying element enters the titanium matrix, completing the oxygenation and alloying of the titanium alloy in one step. Therefore, the technical solution of this invention enables uniform oxygen distribution and the absence of oxide inclusions in titanium alloy products, thereby improving the mechanical properties of the titanium alloy; furthermore, it allows for the synergistic addition of alloying elements and oxygen, simplifying the process flow. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A flowchart illustrating a method for oxygenating titanium alloys according to an embodiment of the present invention is shown. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0022] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0023] refer to Figure 1 This invention proposes a method for oxygenating titanium alloys, comprising the following steps: S1, Add the target additive to titanium tetrachloride and mix evenly to obtain a mixture; wherein the target additive includes at least a chloride containing the target alloying element and oxygen element; S2, the mixture is added to liquid magnesium to carry out a reduction reaction to obtain a reaction product containing titanium alloy; S3. The reaction products are separated to obtain oxygenated titanium alloy products.

[0024] In the technical solution of this invention, a target additive comprising at least a chloride containing the target alloying element and oxygen is added to titanium tetrachloride. Utilizing the good miscibility of this type of chloride with titanium tetrachloride in the liquid state, uniform mixing of the target additive and titanium tetrachloride at the molecular level is achieved, ensuring uniform dispersion of oxygen in the titanium matrix after the reduction reaction. The resulting mixture is then added to liquid magnesium for a reduction reaction, allowing the chloride containing the target alloying element and oxygen to be simultaneously reduced by magnesium along with the titanium tetrachloride. Oxygen directly enters the titanium lattice to form a uniform interstitial solid solution without oxide inclusions, while the target alloying element enters the titanium matrix, completing the oxygenation and alloying of the titanium alloy in one step. Therefore, the technical solution of this invention enables uniform oxygen distribution and the absence of oxide inclusions in titanium alloy products, thereby improving the mechanical properties of the titanium alloy; furthermore, it allows for the synergistic addition of alloying elements and oxygen, simplifying the process flow.

[0025] In some embodiments, in step S1, the chloride containing the target alloying element and oxygen includes at least one of VOCl3 and AlOCl. The resulting titanium alloy product includes any one of titanium-aluminum alloy, titanium-vanadium alloy, and titanium-aluminum-vanadium alloy.

[0026] In some embodiments, in step S1, the additive may further include a chloride containing the target alloying element but without oxygen, such as, but not limited to, AlCl3. In other embodiments, the additive may further include a non-chloride oxygen source, such as, but not limited to, H2O. Preferably, the additive may include both a chloride containing the target alloying element but without oxygen and a non-chloride oxygen source. In this invention, a chloride containing the target alloying element and oxygen is used as the main additive, and a chloride containing the target alloying element but without oxygen and / or a non-chloride oxygen source is used as an auxiliary additive. The additive may include both the main additive and the auxiliary additive, or it may include only the main additive without the auxiliary additive. The auxiliary additive is used to independently supplement the target alloying element and / or adjust the oxygen content based on the basic oxygen content and target alloying element content provided by the main additive, thereby making the control of alloy composition and oxygen content more flexible and precise.

[0027] In some embodiments, in step S1, the amount of the target additive added is calculated and controlled according to the oxygen content requirement of the target titanium alloy, so that the oxygen content of the titanium alloy product is 0.1 to 1.5 wt%. This fully utilizes the solid solution strengthening effect of oxygen to significantly improve the strength of the titanium alloy, while avoiding excessive oxygen leading to plasticity deterioration, thus ensuring that a titanium alloy product with a good match between strength and plasticity is obtained.

[0028] In some embodiments, in step S1, uniform mixing is achieved by stirring for 30–120 minutes at a speed of 50–200 rpm. By controlling the stirring parameters, the oxychloride and titanium tetrachloride are thoroughly mixed in the liquid state and uniformly dispersed at the molecular level.

[0029] In some embodiments, in step S2, the mixture is added to liquid magnesium in a gaseous form, so that titanium tetrachloride and the target additive are continuously and stably introduced into the liquid magnesium in a gaseous form while maintaining a uniform molecular-level mixture. The uniform distribution characteristics of the gaseous feed promote the synchronous contact and reaction between the two and the liquid magnesium.

[0030] In some embodiments, in step S2, the mixture is added to liquid magnesium at 660–900°C to maintain the liquid magnesium in a molten state, providing sufficient fluidity to allow the gaseous reactants to fully contact and react rapidly with the liquid magnesium. In some embodiments, the reduction reaction temperature is 750–850°C, and the reaction time is 8–24 hours. By controlling the temperature and time of the reduction reaction, the magnesium thermal reduction reaction is carried out under stable kinetic conditions, ensuring that titanium tetrachloride and the target additive are simultaneously and fully reduced by magnesium, while promoting the uniform diffusion and complete solid solution of oxygen atoms in the titanium lattice.

[0031] In some embodiments, in step S2, the reduction reaction is carried out in an inert protective atmosphere to prevent the titanium alloy from oxidizing or nitriding at high temperatures, thus ensuring the purity of the titanium alloy product. The inert protective atmosphere can be argon, helium, or a mixture thereof, and the atmosphere pressure is slightly positive.

[0032] In some embodiments, step S3 includes vacuum distillation to separate the MgCl2 byproduct and excess metallic magnesium from the reaction product. In some embodiments, in step S3, the vacuum distillation temperature is 900–1100°C, the vacuum degree is ≤10 Pa, and the distillation time is 20–60 hours, thereby allowing MgCl2 and residual metallic magnesium to fully volatilize and completely separate from the titanium alloy product under high temperature and high vacuum conditions. The final titanium alloy product has oxygen uniformly distributed in the form of interstitial solid solution, without oxide inclusions or defects.

[0033] In summary, this invention provides a method for oxygenating titanium alloys, which achieves uniform introduction of oxygen from the source of raw materials, fundamentally solving the problems of oxygen segregation and oxide inclusions.

[0034] Compared with the prior art, the present invention has the following advantages: (1) Uniform distribution of oxygen: In the raw material stage of titanium tetrachloride, the present invention introduces oxygen-containing chloride as oxygen source. The oxygen-containing chloride and titanium tetrachloride are uniformly mixed at the molecular level. After magnesium thermal reduction, the oxygen element is uniformly dispersed in the titanium matrix at the atomic level, which fundamentally avoids the problem of uneven oxygen distribution caused by the segregation of TiO2 powder in the traditional method.

[0035] (2) No oxide inclusion defects: The present invention uses oxychloride as oxygen source. During the reduction process, oxychloride and titanium tetrachloride are reduced by magnesium at the same time. Oxygen elements directly enter the titanium lattice to form interstitial solid solution, and no oxide inclusions such as TiO2 are generated. This effectively avoids the adverse effects of oxide inclusions on the mechanical properties of titanium alloys.

[0036] (3) Synergistic addition of alloying elements and oxygen elements: The oxygen-containing chlorides (such as VOCl3, AlOCl, etc.) used in this invention contain both alloying elements (V, Al, etc.) and oxygen elements, which can achieve the addition of alloying elements while increasing oxygen, and complete alloying and oxygenation in one step, simplifying the process.

[0037] (4) Precise and controllable oxygen content: By precisely controlling the amount of oxychloride added, the oxygen content in the titanium alloy can be precisely controlled, resulting in high oxygen content control accuracy and good product quality stability.

[0038] (5) Significantly improved mechanical properties: Due to the uniform distribution of oxygen and the absence of oxide inclusions, the oxygenated titanium alloy prepared by this invention can fully exert the solid solution strengthening effect of oxygen, resulting in a significant increase in strength while maintaining good plasticity, with excellent strength-plasticity matching.

[0039] (6) Simple process and easy to industrialize: This invention is based on the traditional Klauer process and is improved. No new complex equipment is required. The process is simple and easy to realize industrial production. It has broad prospects for promotion and application.

[0040] The following description is based on specific embodiments and comparative examples.

[0041] Example 1 (1) Take 1000 kg of purified titanium tetrachloride (TiCl4 purity ≥ 99.9%), add 25 kg of AlOCl and 5 kg of AlCl3 to it, stir at 100 rpm for 60 minutes at room temperature, mix thoroughly and evenly to obtain mixture A; (2) Add metallic magnesium to the reduction reactor, evacuate and then fill with argon for protection, heat to 800℃ to melt magnesium and form liquid magnesium; heat mixture A to vaporize and then pass it into the reduction reactor at a certain rate to react with liquid magnesium. The reaction temperature is controlled at 800±10℃ and the reaction time is 16 hours. During the reaction, maintain a slightly positive pressure argon atmosphere. (3) After the reduction reaction is completed, the reactor is heated to 1000℃ and vacuumed to ≤5Pa. Vacuum distillation is carried out for 40 hours to remove residual magnesium and magnesium chloride. After cooling, the product is taken out to obtain oxygenated titanium-aluminum alloy.

[0042] Testing revealed that the titanium alloy prepared in this embodiment contained 0.35 wt% oxygen and 6.2 wt% aluminum, with uniform oxygen distribution and no oxide inclusions. Its tensile strength reached 980 MPa, yield strength reached 860 MPa, and elongation was 18.5%. Compared to ordinary titanium alloys with the same aluminum content, the tensile strength increased by approximately 15%, the yield strength increased by approximately 18%, while maintaining good plasticity.

[0043] Example 2 (1) Take 1000 kg of purified titanium tetrachloride, add 40 kg of VOCl3 to it, stir at 80 rpm for 90 minutes at room temperature, mix thoroughly and evenly to obtain mixture A; (2) Add metallic magnesium to the reduction reactor, evacuate and then fill with argon for protection, heat to 780°C to melt magnesium and form liquid magnesium; heat mixture A to vaporize and then pass it into the reduction reactor at a certain rate to react with liquid magnesium. The reaction temperature is controlled at 780±20°C and the reaction time is 20 hours. During the reaction, maintain a slightly positive pressure argon atmosphere. (3) After the reduction reaction is completed, the reactor is heated to 950°C and vacuumed to ≤8Pa. Vacuum distillation is carried out for 50 hours to remove residual magnesium and magnesium chloride. After cooling, the product is taken out to obtain oxygenated titanium vanadium alloy.

[0044] Testing revealed that the titanium alloy prepared in this embodiment contained 0.52 wt% oxygen and 4.1 wt% vanadium, with uniform oxygen distribution and no obvious oxide inclusions. Its tensile strength reached 1050 MPa, yield strength reached 940 MPa, and elongation was 16.8%. Compared with ordinary titanium-vanadium alloys with the same vanadium content, the tensile strength increased by approximately 18%, and the yield strength increased by approximately 22%, demonstrating excellent overall mechanical properties.

[0045] Example 3 (1) Take 1000 kg of purified titanium tetrachloride, add 30 kg of AlOCl, 45 kg of VOCl3 and 2 kg of H2O to it, stir at 120 rpm for 45 minutes at room temperature, mix thoroughly and evenly to obtain mixture A; (2) Add metallic magnesium to the reduction reactor, evacuate and then fill with argon for protection, heat to 820°C to melt magnesium and form liquid magnesium; heat mixture A to vaporize and then pass it into the reduction reactor at a certain rate to react with liquid magnesium. The reaction temperature is controlled at 820±20°C and the reaction time is 18 hours. During the reaction, maintain a slightly positive pressure argon atmosphere. (3) After the reduction reaction is completed, the reactor is heated to 1050℃ and vacuumed to ≤3Pa. Vacuum distillation is carried out for 30 hours to remove residual magnesium and magnesium chloride. After cooling, the product is taken out to obtain oxygenated titanium-aluminum-vanadium alloy.

[0046] Testing revealed that the titanium alloy prepared in this embodiment contained 0.85 wt% oxygen, 6.1 wt% aluminum, and 3.9 wt% vanadium. Oxygen was uniformly distributed in the matrix, and no oxide inclusions were found. Its tensile strength reached 1280 MPa, its yield strength reached 1180 MPa, and its elongation was 12.5%. Compared to ordinary Ti-6Al-4V alloy (oxygen content approximately 0.2 wt%), the tensile strength increased by approximately 32%, and the yield strength increased by approximately 38%, demonstrating a significant improvement in strength while maintaining an acceptable level of plasticity.

[0047] Example 4 (1) Take 1000 kg of purified titanium tetrachloride, add 60 kg of AlOCl, 50 kg of VOCl3 and 5 kg of H2O to it, stir at 150 rpm for 30 minutes at room temperature, mix thoroughly and evenly to obtain mixture A; (2) Add metallic magnesium to the reduction reactor, evacuate and then fill with argon for protection, heat to 850°C to melt magnesium and form liquid magnesium; heat mixture A to vaporize and then pass it into the reduction reactor at a certain rate to react with liquid magnesium. The reaction temperature is controlled at 850±20°C and the reaction time is 12 hours. During the reaction, the argon atmosphere pressure is maintained at 0.15MPa. (3) After the reduction reaction is completed, the reactor is heated to 1080℃, and the vacuum is drawn to ≤2Pa. Vacuum distillation is carried out for 25 hours to remove residual magnesium and magnesium chloride. After cooling, the product is taken out to obtain a titanium alloy product with ultra-high oxygen content.

[0048] Testing revealed that the titanium alloy prepared in this embodiment contains 1.35 wt% oxygen, 10.5 wt% aluminum, and 4.3 wt% vanadium, with uniform oxygen distribution and no oxide inclusions. Its tensile strength reaches 1420 MPa, yield strength reaches 1320 MPa, and elongation is 8.2%, making it suitable for applications requiring extremely high strength.

[0049] Comparative Example 1 Ti-6Al-4V alloy was prepared using a traditional method: sponge titanium, aluminum-vanadium master alloy and TiO2 powder were mixed in proportion, and titanium alloy was prepared by mixing, pressing electrodes and vacuum arc melting, with the oxygen content controlled to be about 0.85wt%.

[0050] Testing revealed significant oxygen segregation in the titanium alloy prepared using conventional methods, with local oxygen content deviations reaching ±30%, and the presence of a small amount of micron-sized TiO2 inclusions. Its tensile strength was 1120 MPa, yield strength was 1010 MPa, and elongation was 9.8%. Compared to Example 3, under similar oxygen content conditions, the titanium alloy prepared by the method of this invention exhibits higher strength, better plasticity, and significantly superior overall mechanical properties compared to the conventional method.

[0051] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for oxygenating titanium alloys, characterized in that, Includes the following steps: S1, Add the target additive to titanium tetrachloride and mix evenly to obtain a mixture; wherein the target additive includes at least a chloride containing the target alloying element and oxygen element; S2, the mixture is added to liquid magnesium to carry out a reduction reaction to obtain a reaction product containing titanium alloy; S3, the reaction products are separated to obtain an oxygenated titanium alloy product.

2. The method according to claim 1, characterized in that, In step S1, the chloride containing the target alloying element and oxygen element includes at least one of VOCl3 and AlOCl.

3. The method according to claim 1, characterized in that, In step S1, the additive further includes at least one of a chloride and a non-chloride oxygen source containing the target alloying element and free of oxygen.

4. The method according to claim 3, characterized in that, In step S1, the chloride containing the target alloying element and not containing oxygen includes AlCl3, and the non-chloride oxygen source includes H2O.

5. The method according to claim 1, characterized in that, In step S1, the amount of the target additive added is such that the oxygen content of the titanium alloy product is 0.1 to 1.5 wt%.

6. The method according to claim 1, characterized in that, In step S1, the mixture is made uniform by stirring for 30 to 120 minutes at a speed of 50 to 200 rpm.

7. The method according to claim 1, characterized in that, In step S2, the mixture is added to the liquid magnesium in gaseous form.

8. The method according to claim 1, characterized in that, In step S2, the mixture is added to liquid magnesium at 660–900°C; the reduction reaction is carried out at 750–850°C for 8–24 hours.

9. The method according to claim 1, characterized in that, In step S2, the reduction reaction is carried out in an inert protective atmosphere.

10. The method according to claim 1, characterized in that, In step S3, the separation process includes vacuum distillation to separate MgCl2 and metallic magnesium from the reaction products; the vacuum distillation temperature is 900-1100℃, the vacuum degree is ≤10Pa, and the distillation time is 20-60 hours.

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