A method for controlling the orientation of high-niobium titanium-aluminum alloy sheets

Abstract

This invention discloses a method for controlling the lamellar orientation of high-niobium titanium-aluminum alloys. The method involves coating the surface of the high-niobium titanium-aluminum alloy with boron nitride glass lubricant; wrapping the high-niobium titanium-aluminum alloy with pure nickel foil and encapsulating it in a metal sleeve; heating the high-niobium titanium-aluminum alloy extrusion billet assembly to the (α+β) two-phase region and holding it at that temperature; rolling-coating with boron nitride glass lubricant and then extruding and air-cooling to room temperature; reheating to the β single-phase region and holding it at that temperature; after holding at that temperature, slow cooling to the α single-phase region and holding it at that temperature; and finally, air-cooling to room temperature. This method significantly reduces the dependence on equipment, thereby greatly shortening the time required to control the lamellar orientation. This method can produce 5-8 high-niobium TiAl parts at a time, reducing the preparation time to 1 / 5 to 1 / 8. The method proposed in this invention not only fully utilizes the excellent hot working properties of high-niobium TiAl alloys but is also suitable for controlling the lamellar orientation of high-niobium TiAl alloys as wrought alloys.

Description

Technical Field

[0001] This invention belongs to the field of metal material hot working technology, specifically relating to a method for controlling the orientation of high-niobium titanium-aluminum alloy sheets. Background Art

[0002] Titanium-aluminum alloys possess low density, high specific stiffness, high specific strength, and excellent oxidation and creep resistance, making them highly promising for applications in the aerospace and automotive manufacturing industries. However, traditional titanium-aluminum alloys have relatively low service temperatures, ranging from 650℃ to 750℃. To increase the service temperature of titanium-aluminum alloys, the high-melting-point element niobium is typically added to the alloy, forming a high-niobium titanium-aluminum alloy system with a composition range of Ti-(40-45)Al-(5-10)Nb. Compared to traditional titanium-aluminum alloys, high-niobium titanium-aluminum alloys can achieve service temperatures of 800℃ to 900℃, while also exhibiting significantly improved hot working properties.

[0003] High-niobium titanium-aluminum alloys consist of α2 and γ phases, exhibiting a lamellar structure across the temperature range from room temperature to service temperature. The mechanical properties of high-niobium titanium-aluminum alloys are significantly affected by lamellar orientation: when the loading direction is parallel to the lamellar direction, the high-niobium alloy exhibits excellent strength-ductility matching in the temperature range from room temperature to 900℃, with a creep life 10 times higher and a fatigue life up to 1000°C compared to traditional titanium-aluminum alloys. 7 Therefore, controlling the lamellar orientation is crucial for improving the overall mechanical properties of high-niobium titanium-aluminum alloys. However, high-niobium titanium-aluminum alloys undergo a β→α solid-state phase transformation, during which 12 α-phase variants precipitate from the β matrix, making it difficult to control the orientation of the lamellar structure after the α-phase and α→α2+γ phase transformation.

[0004] Patent publication number CN 108220850 A, entitled "A Method for Reducing Phase Transformation Texture of High-Niobium Titanium-Aluminum Alloy," discloses a method for reducing phase transformation texture in high-niobium titanium-aluminum alloy, belonging to the field of metal heat treatment technology. It reduces the phase transformation texture of titanium-aluminum alloy through pre-deformation in the β single-phase region, which is simple to operate, has a short cycle, and significantly reduces production costs. Compared to heat treatment methods, the cycle is shorter. Compared to boron addition methods, pre-deformation in the β single-phase region of high-niobium titanium-aluminum alloy can cause the coarse, elongated TiB to break down, thereby increasing the heterogeneous nucleation sites that promote the formation of the non-textured α phase. Simultaneously, due to the different deformation mechanisms of TiB and the β phase, the orientation relationship between TiB and the β phase changes during the pre-deformation process, altering their original orientation relationship: {110}β∥(001)TiB and... <111> β∥

[010] TiB is destroyed, thus ensuring that the α phase precipitated on the boride is all non-textured α phase, reducing stress concentration in the high-niobium titanium-aluminum alloy, and at the same time randomizing the crack propagation channel, weakening the cracking tendency of the alloy. Although this patent application can weaken the phase transformation of high-niobium titanium-aluminum alloy, it cannot achieve the lamellar orientation of high-niobium titanium-aluminum alloy, and the problems it solves are not the same.

[0005] Currently, the control of lamellar orientation in high-niobium titanium-aluminum alloys mainly relies on directional solidification technology. However, due to limitations in directional solidification equipment, this technology is time-consuming. Furthermore, directional solidification is more suitable for cast titanium-aluminum alloys and cannot fully utilize the excellent hot working properties of high-niobium titanium-aluminum alloys. Therefore, there is an urgent need to develop a hot deformation method to achieve the goal of controlling the lamellar orientation of high-niobium titanium-aluminum alloys. Summary of the Invention

[0006] To overcome the problems existing in the prior art, the present invention aims to provide a novel method for controlling the lamellar orientation of high-niobium titanium-aluminum alloys. The core of this method is to utilize the heterogeneous nucleation effect of TiB on the α-phase to control the α-transformation, thereby achieving control over the lamellar orientation after the α→α2+γ phase transformation. The technical route of this method includes hot extrusion in the (α+β) two-phase region and controlled heat treatment during the solid-state phase transformation process. Hot extrusion allows for preferred TiB orientation in the high-niobium titanium-aluminum alloy, while controlled heat treatment during the solid-state phase transformation enables selective precipitation of the α-phase from the preferred TiB, thus achieving control over the lamellar orientation of the high-niobium titanium-aluminum alloy.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a method for controlling the orientation of high-niobium titanium-aluminum alloy sheets, comprising the following steps:

[0008] S1: Coat the surface of the high-niobium titanium-aluminum alloy with boron nitride glass lubricant;

[0009] S2: A high-niobium titanium-aluminum alloy coated with boron nitride glass lubricant is wrapped with pure nickel foil, placed in a metal sleeve and encapsulated to form a high-niobium titanium-aluminum alloy extruded billet assembly.

[0010] S3: Heat the high-niobium titanium-aluminum alloy extruded billet assembly to the (α+β) two-phase region and hold it at that temperature;

[0011] S4: After rolling on boron nitride glass lubricant, extrude and air cool to room temperature;

[0012] S5: Reheat to the β single-phase region and hold for a period of time. After holding for a period of time, cool to the α single-phase region by slow cooling and hold for a period of time. After holding for a period of time, air cool to room temperature.

[0013] Optionally, in step S1, the high-niobium titanium-aluminum alloy is made from a high-niobium titanium-aluminum alloy rod.

[0014] Optionally, before step S1, the surface of the high-niobium titanium-aluminum alloy is polished and ultrasonically cleaned.

[0015] Optionally, in step S2, the encapsulation is performed using a soldering method.

[0016] Optionally, in step S3, the temperature of the (α+β) two-phase region is 1260℃~1350℃.

[0017] Optionally, in step S3, the heat preservation time is 1 hour.

[0018] Optionally, in step S4, the preheating temperature of the die during hot extrusion is 300℃~500℃.

[0019] Optionally, in step S5, the temperature of the β single-phase region is 1370℃~1420℃, and the temperature of the α single-phase region is 1120℃~1200℃.

[0020] Optionally, in step S5, the heat preservation time for the β single-phase region is 5 to 10 minutes, and the heat preservation time for the α single-phase region is 1 to 3 hours.

[0021] Optionally, in step S5, the cooling rate after the β single-phase region is kept at a constant temperature is 0.005℃ / s to 0.0001℃ / s.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention discloses a method for controlling the lamellar orientation of high-niobium titanium-aluminum alloys. The core of this method is to utilize the heterogeneous nucleation effect of TiB on the α-phase to control the α-transformation, thereby controlling the lamellar orientation of the high-niobium TiAl alloy. This method differs in principle from the current mainstream directional solidification technology. Specifically, directional solidification technology should avoid α-tribe crystals caused by heterogeneous nucleation points when controlling lamellar orientation; this method introduces heterogeneous nucleation points TiB into the high-niobium titanium-aluminum alloy and achieves precise control of lamellar orientation by controlling the α-tribe crystals precipitated on the boride. Due to the difference in principle between the two methods, this method achieves the following beneficial effects: This method significantly reduces dependence on equipment, thereby greatly shortening the time required to control lamellar orientation. Directional solidification equipment can only produce one high-niobium TiAl alloy part at a time, while this method can produce 5-8 high-niobium TiAl parts at a time, reducing the preparation time to 1 / 5 to 1 / 8. Directional solidification technology is more suitable for casting TiAl alloys and cannot fully utilize the excellent hot working properties of high-niobium TiAl alloys. The new method proposed in this invention can not only fully utilize the excellent hot working properties of high-niobium TiAl alloys, but is also more suitable for controlling the lamellar orientation of high-niobium TiAl alloys as wrought alloys. Attached Figure Description

[0024] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely schematic to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. In the drawings:

[0025] Figure 1 The microstructure of the Ti40Al8Nb0.5B alloy rod in Example 1;

[0026] Figure 2 The image shows the microstructure of the Ti40Al8Nb0.5B alloy after hot extrusion in Example 1.

[0027] Figure 3 The image shows the microstructure of the Ti40Al8Nb0.5B alloy after controlled heat treatment in Example 1.

[0028] Figure 4 This is a photograph of the microstructure of the Ti45A10Nb1B alloy after hot extrusion in Example 2;

[0029] Figure 5 A photograph of the microstructure of the Ti42Al5Nb0.7B alloy after controlled heat treatment, provided in Example 3;

[0030] Figure 6 This is a flowchart of an embodiment of the present invention. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0032] 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 herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0033] The present invention will now be described in detail with reference to the accompanying drawings.

[0034] like Figure 6 As shown, the present invention provides a method for controlling the orientation of high-niobium titanium-aluminum alloy sheets, comprising the following steps:

[0035] High-niobium titanium-aluminum alloy test bars were cut from high-niobium titanium-aluminum alloy ingots using wire cutting. The surfaces of the cut test bars were then polished and ultrasonically cleaned.

[0036] After grinding and cleaning, the surface of the high-niobium titanium-aluminum alloy test rod is coated with a glass lubricant, specifically boron nitride. The coated test rod is then wrapped with a 1mm thick high-temperature metal foil, which can be tantalum foil, niobium foil, or pure nickel foil.

[0037] A high-niobium titanium-aluminum alloy test rod, wrapped in nickel foil, is placed in a cylindrical sleeve made of stainless steel. The gap between the titanium-aluminum rod and the stainless steel sleeve is then filled with insulating cotton, specifically aluminum zirconate fiber cloth. The rod is then encapsulated using welding to obtain a titanium-aluminum alloy extruded blank assembly.

[0038] The high-niobium titanium-aluminum alloy extruded billet assembly was placed in a heat treatment furnace and heated to the (α+β) two-phase region, specifically 1260℃~1350℃, and held for 1 hour.

[0039] After the heat preservation period, the high-niobium titanium-aluminum alloy extruded billet is removed, quickly coated with boron nitride glass lubricant, and then extruded. During hot extrusion, the die preheating temperature is 300℃~500℃, the extrusion ratio is 9~16, and the extrusion rate is 7~10mm / s. After extrusion, the resulting bar is air-cooled to room temperature.

[0040] The high-niobium titanium-aluminum alloy rods obtained after extrusion and air cooling are reheated to the β single-phase region, specifically 1370℃~1420℃, and held for 5min~10min. After holding, they are slowly cooled to the α single-phase region, specifically 1120℃~1200℃, using a slow cooling method (0.005℃ / s~0.0001℃ / s), and held for 1h~3h. After holding in the α single-phase region, they are air-cooled to room temperature, thus achieving control over the lamellar orientation of the high-niobium titanium-aluminum alloy.

[0041] Example 1

[0042] Figure 6 The flowchart is an embodiment of the present invention, such as Figure 6 As shown, a method for controlling the extraction of high-niobium titanium-aluminum alloy sheets includes:

[0043] 1) Alloy test bars with a diameter of 50mm × 60mm were cut using wire cutting. The high-niobium titanium-aluminum alloy was Ti40Al8Nb0.5B alloy. The obtained high-niobium titanium-aluminum alloy test bars were polished and ultrasonically cleaned.

[0044] 2) A 1mm thick layer of boron nitride glass lubricant was applied to the surface of a high-niobium titanium-aluminum alloy test rod. The coated rod was then wrapped with a 1mm thick layer of pure nickel foil. The nickel-foil-wrapped sample was placed in a cylindrical stainless steel sheath with an inner diameter of 68mm, a height of 55mm, and a sheath thickness of 8mm. The gap between the high-niobium titanium-aluminum alloy rod and the stainless steel sheath was filled with aluminum zirconate fiber cloth. The assembly was then sealed using welding to obtain the titanium-aluminum alloy extruded blank component.

[0045] 3) Place the high-niobium titanium-aluminum alloy extrusion billet assembly in a heat treatment furnace, heat to 1260℃, and hold for 1 hour. After holding, remove the high-niobium titanium-aluminum alloy extrusion billet, quickly roll-coat it with boron nitride glass lubricant, and then extrude it. During hot extrusion, the die preheating temperature is 300℃, the extrusion ratio is 9, and the extrusion rate is 10mm / s. After extrusion, the resulting bar is air-cooled to room temperature.

[0046] 4) The high-niobium titanium-aluminum alloy rods obtained after extrusion and air cooling are reheated to the β single-phase region, specifically at 1370℃ for 5 minutes. After the holding period, they are cooled to 1170℃ at a cooling rate of 0.005℃ / s and held for 2 hours. After the holding period, they are air-cooled to room temperature.

[0047] Figure 1 The microstructure of a Ti40Al8Nb0.5B alloy specimen. Figure 2 The image shows the microstructure of a Ti40Al8Nb0.5B alloy specimen after hot extrusion in the (α+β) two-phase region. Compared to the Ti40Al8Nb0.5B alloy specimen, the borides in the Ti40Al8Nb0.5B alloy after hot extrusion in the (α+β) two-phase region exhibit a preferred orientation, which is caused by the rigid rotation of the borides during the extrusion process.

[0048] Figure 3 The image shows the microstructure of Ti40Al8Nb0.5B alloy after controlled heat treatment. Compared with the original Ti40Al8Nb0.5B alloy specimen, the method provided by this invention can transform the randomly oriented lamellae in the original Ti40Al8Nb0.5B alloy specimen into unidirectional lamellae, achieving control over the lamellar orientation of the high-niobium titanium-aluminum alloy. This is because the selective precipitation of the α phase on orientation-preferred borides during controlled heat treatment achieves control over the α orientation. Since the lamellar orientation in the Ti40Al8Nb0.5B alloy is determined by the orientation of α, precise control over the lamellar orientation is achieved.

[0049] Example 2

[0050] Figure 6 The flowchart is an embodiment of the present invention, such as Figure 6 As shown, a method for controlling the extraction of high-niobium titanium-aluminum alloy sheets includes:

[0051] 1) Alloy test bars with a diameter of Φ50mm × 60mm were cut by wire cutting. The high-niobium titanium-aluminum alloy was Ti45A10Nb1B alloy. The obtained high-niobium titanium-aluminum alloy test bars were polished and ultrasonically cleaned.

[0052] 2) Coat the surface of the high-niobium titanium-aluminum alloy test rod from step 1 with boron nitride glass lubricant to a thickness of 2 mm. Wrap the coated test rod with pure nickel foil to a thickness of 1 mm. Place the nickel foil-wrapped sample in a cylindrical sleeve made of 1Cr18Ni9Ti stainless steel, with an inner diameter of 68 mm, a height of 55 mm, and a sleeve thickness of 8 mm. Fill the gap between the titanium-aluminum rod and the stainless steel sleeve with aluminum zirconate fiber cloth. Seal the sample using a welding method to obtain a titanium-aluminum alloy extruded blank assembly.

[0053] 3) Place the high-niobium titanium-aluminum alloy extrusion billet assembly in a heat treatment furnace, heat to 1350℃, and hold for 1 hour. After holding, remove the high-niobium titanium-aluminum alloy extrusion billet, quickly roll-coat it with boron nitride glass lubricant, and then extrude it. During hot extrusion, the die preheating temperature is 400℃, the extrusion ratio is 16, and the extrusion rate is 7mm / s. After extrusion, the resulting bar is air-cooled to room temperature.

[0054] 4) The high-niobium titanium-aluminum alloy rods obtained after extrusion and air cooling are reheated to 1420℃ in the β single-phase region and held for 10 min. After holding, they are cooled to 1120℃ at a cooling rate of 0.0001℃ / s and held for 1 hour. After holding, they are air-cooled to room temperature to achieve control of the high-niobium titanium-aluminum alloy sheet orientation.

[0055] like Figure 4 This is a photograph of the microstructure of Ti45A10Nb1B alloy after hot extrusion.

[0056] Example 3

[0057] Figure 6 The flowchart is an embodiment of the present invention, such as Figure 6 As shown, a method for controlling the extraction of high-niobium titanium-aluminum alloy sheets includes:

[0058] 1) Alloy test bars with a diameter of Φ50mm × 60mm were cut using wire cutting. The high-niobium titanium-aluminum alloy was Ti42A5Nb0.7B alloy. The obtained high-niobium titanium-aluminum alloy test bars were polished and ultrasonically cleaned.

[0059] 2) Coat the surface of the high-niobium titanium-aluminum alloy test rod from step 1 with boron nitride glass lubricant to a thickness of 1.5 mm. Wrap the coated test rod with pure nickel foil to a thickness of 1 mm. Place the nickel foil-wrapped sample in a cylindrical sleeve made of 1Cr18Ni9Ti stainless steel, with an inner diameter of 68 mm, a height of 55 mm, and a sleeve thickness of 8 mm. Fill the gap between the titanium-aluminum rod and the stainless steel sleeve with aluminum zirconate fiber cloth. Seal the sample using a welding method to obtain a titanium-aluminum alloy extruded blank assembly.

[0060] 3) Place the high-niobium titanium-aluminum alloy extrusion billet assembly in a heat treatment furnace, heat to 1300℃, and hold for 1 hour. After holding, remove the high-niobium titanium-aluminum alloy extrusion billet, quickly roll-coat it with boron nitride glass lubricant, and then extrude it. During hot extrusion, the die preheating temperature is 500℃, the extrusion ratio is 12, and the extrusion rate is 8mm / s. After extrusion, the resulting bar is air-cooled to room temperature.

[0061] 4) The high-niobium titanium-aluminum alloy rods obtained after extrusion and air cooling are reheated to 1400℃ in the β single-phase region and held for 8 minutes. After holding, they are cooled to 1200℃ at a cooling rate of 0.008℃ / s and held for 3 hours. After holding, they are air-cooled to room temperature to achieve control of the lamellar orientation of the high-niobium titanium-aluminum alloy. Figure 5 Photograph of the microstructure of Ti42Al5Nb0.7B alloy after controlled heat treatment.

[0062] Unless otherwise specified, the equipment components involved in the above embodiments are all conventional equipment components, and the structural settings, working methods or control methods involved are all conventional settings, working methods or control methods in the art unless otherwise specified.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for controlling the orientation of high-niobium titanium-aluminum alloy lamellars, characterized in that, The following steps are involved: S1: Coat the surface of the high-niobium titanium-aluminum alloy with boron nitride glass lubricant; S2: A high-niobium titanium-aluminum alloy coated with boron nitride glass lubricant is wrapped with pure nickel foil, placed in a metal sleeve and encapsulated to form a high-niobium titanium-aluminum alloy extruded billet assembly. S3: Heat the high-niobium titanium-aluminum alloy extruded billet assembly to the (α+β) two-phase region and hold it at that temperature; S4: After rolling on boron nitride glass lubricant, extrude and air cool to room temperature; S5: Reheat to the β single-phase region and hold at that temperature. After holding, cool slowly to the α single-phase region and hold at that temperature. After holding, air cool to room temperature. In step S3, the temperature of the (α+β) two-phase region is 1260℃~1350℃; in step S5, the temperature of the β single-phase region is 1370℃~1420℃, and the temperature of the α single-phase region is 1120℃~1200℃.

2. The method for controlling the orientation of high-niobium titanium-aluminum alloy laminations according to claim 1, characterized in that, In step S1, the high-niobium titanium-aluminum alloy is made using a high-niobium titanium-aluminum alloy rod.

3. The method for controlling the orientation of high-niobium titanium-aluminum alloy sheets according to claim 1, characterized in that, Before step S1, the surface of the high-niobium titanium-aluminum alloy is first polished and ultrasonically cleaned.

4. The method for controlling the orientation of high-niobium titanium-aluminum alloy sheets according to claim 1, characterized in that, In step S2, the encapsulation is performed using a soldering method.

5. The method for controlling the orientation of high-niobium titanium-aluminum alloy sheets according to claim 1, characterized in that, In step S3, the heat preservation time is 1 hour.

6. The method for controlling the orientation of high-niobium titanium-aluminum alloy sheets according to claim 1, characterized in that, In step S4, the preheating temperature of the die during hot extrusion is 300℃~500℃.

7. The method for controlling the orientation of high-niobium titanium-aluminum alloy sheets according to claim 1, characterized in that, In step S5, the heat preservation time for the β single-phase region is 5~10 min, and the heat preservation time for the α single-phase region is 1~3 hours.

8. The method for controlling the orientation of high-niobium titanium-aluminum alloy laminations according to claim 1, characterized in that, In step S5, after the β single-phase region is kept at a constant temperature, the cooling rate is 0.005℃ / s to 0.0001℃ / s.

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