Rare earth Y microalloyed lightweight Nb-Ti-Al-based alloy and preparation method thereof

Abstract

The invention discloses a rare earth Y microalloyed lightweight Nb-Ti-Al-based alloy and a preparation method thereof, and relates to the technical field of metal materials. The light Nb-Ti-Al-based alloy comprises Ti, Al, V, Zr, Mo, Hf, Y and Nb, and the light Nb-Ti-Al-based alloy comprises, by atomic percent, 36%-38% of Ti, 4%-8% of Al, 1%-5% of V, 1%-3% of Zr, 0.5%-3% of Mo, 1% of Hf, 0.01%-0.5% of Y and the balance Nb. According to the light Nb-Ti-Al-based alloy microalloyed by introducing the rare earth Y, the grain refinement effect is achieved, the room-temperature fracture toughness of the alloy is effectively improved, the high-temperature strength of the alloy is improved to a certain extent, meanwhile, formation of an oxidation film at the high temperature is facilitated, and therefore the high-temperature oxidation resistance of the alloy is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal materials, in particular to a rare earth Y micro-alloyed light Nb-Ti-Al based alloy and a preparation method thereof. BACKGROUND

[0002] With the continuous development of aerospace technology, the use temperature of existing high-temperature alloys has been difficult to meet the working requirements of new aerospace vehicles, and it is urgent to develop new high-temperature structural materials. Among many candidate materials, Nb-based alloys are of great concern due to their high melting point, excellent high-temperature strength, good toughness, and designability. Among them, Nb-Ti-Al alloy, as a light Nb-based alloy, has excellent toughness and certain high-temperature strength with Nbss (solid solution of niobium) and δ-Nb3Al phase as the main components. However, the alloy currently faces the key problem of mismatch between oxidation resistance and mechanical properties. As the main strengthening phase, δ-Nb3Al, its volume fraction is too high, which will significantly reduce the fracture toughness of the alloy. SUMMARY

[0003] In view of the deficiencies in the background art, the present application provides a rare earth Y micro-alloyed light Nb-Ti-Al based alloy and a preparation method thereof. The light Nb-Ti-Al based alloy after introducing rare earth Y micro-alloying has a grain refinement effect, effectively improves the room temperature fracture toughness of the alloy and to some extent improves the high temperature strength of the alloy, and helps the formation of oxidation film at high temperature to improve the high temperature oxidation resistance of the alloy.

[0004] The first object of the present application is to provide a rare earth Y micro-alloyed light Nb-Ti-Al based alloy, which comprises Ti, Al, V, Zr, Mo, Hf, Y and Nb, and according to 100% of atomic percentage, it comprises: Ti 36-38%, Al 4-8%, V 1-5%, Zr 1-3%, Mo 0.5-3%, Hf 1%, Y 0.01-0.5%, and Nb balance.

[0005] Preferably, the light Nb-Ti-Al based alloy, according to 100% of atomic percentage, comprises: Ti 36-38%, Al 4-8%, V 1-5%, Zr 1-3%, Hf 1%, Mo 1%, Y 0.01-0.2%, and Nb balance.

[0006] Preferably, the light Nb-Ti-Al based alloy comprises niobium-based solid solution grains, and as the content of rare earth Y increases, the grain size decreases.

[0007] Preferably, when the content of rare earth Y is 0.1 at.% and 0.2 at.%, the particle size of the Nb-based solid solution grain corresponds to 330.98 μm and 270.81 μm.

[0008] The second object of the present application is to provide a preparation method of a light Nb-Ti-Al-based alloy micro-alloyed with rare earth Y, comprising the following steps: Take Ti, Al, V, Zr, Hf, Mo, Y and Nb according to atomic percentage to obtain raw materials; According to the melting point from low to high, sequentially stack Al, Ti, Y, Zr, V, Hf, Mo and Nb raw materials into a smelting furnace, vacuumize, and then flush in argon protection to smelt, to obtain an alloy ingot; After repeatedly smelting the alloy ingot for multiple times, a light Nb-Ti-Al-based alloy micro-alloyed with rare earth Y is obtained.

[0009] Preferably, the raw materials are pretreated before being taken to remove surface contaminants and oxide layers.

[0010] Preferably, the vacuumization is to 1×10 -3 Pa, and the argon filling is to 20 KPa-50 KPa.

[0011] Preferably, the repeated smelting is 4-6 times.

[0012] Preferably, the purity of the raw materials is 99.40-99.99%.

[0013] The third object of the present application is to provide an application of the light Nb-Ti-Al-based alloy micro-alloyed with rare earth Y in a high-temperature-resistant structure.

[0014] Compared with the prior art, the present application has the following beneficial effects: The present application provides a light Nb-Ti-Al-based alloy micro-alloyed with rare earth Y and a preparation method thereof. By adding the rare earth Y element, yttrium oxide is formed in the smelting process by combining with a small amount of residual oxygen, which improves the purity of the alloy and reduces the content of oxygen and other elements. The purification of impurity elements at the grain boundary may promote the improvement of the grain boundary strength, thereby improving the high-temperature strength of the alloy.

[0015] In the solidification process, the high-melting-point yttrium oxide can become a heterogeneous nucleation site to promote nucleation, and it also has the effect of pinning grain boundaries. Under the action of these two effects, the grain refinement of the alloy can be realized.

[0016] The present application can improve the high-temperature strength of the alloy through grain refinement and grain boundary strengthening, and the uniformly distributed second-phase particles can have the effect of second-phase strengthening, further improving the high-temperature strength of the alloy.

[0017] The present application prepares the alloy through vacuum non-consumable arc smelting technology, has simple process, high repeatability, and high scientific research and practical value. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Microstructure diagrams of comparative example 1 and examples 1-4; Figure 2 Grain size distribution and statistical diagrams of comparative example 1 and examples 1-4; Figure 3 High-temperature compression strength values of comparative example 1 and examples 1-4; Figure 4 High-temperature oxidation weight gain values of comparative example 1 and examples 1-4; Figure 5 Room temperature fracture toughness condition values of comparative example 1 and examples 1-4. DETAILED DESCRIPTION

[0019] In order to make the skilled in the art better understand the technical solutions of the present application can be implemented, the following specific embodiments and the present application is further described with reference to the drawings, but the examples are not as a limitation of the present application.

[0020] The present application aims to provide a rare earth Y micro-alloyed light Nb-Ti-Al based alloy and a preparation method thereof.

[0021] The present application selects trace rare earth Y as an alloying element, designs a series of Y micro-alloyed light Nb-Ti-Al alloys through system, deeply studies the influence law of Y element on the microstructure morphology and comprehensive performance of the alloy, and aims to realize the comprehensive improvement of the performance of the alloy system.

[0022] In order to achieve the above object, the present application provides a rare earth Y micro-alloyed light Nb-Ti-Al based alloy in the first aspect, the light Nb-Ti-Al based alloy includes Ti, Al, V, Zr, Mo, Hf, Y and Nb, and according to 100% of atomic percentage, it includes: Ti 36-38%, Al 4-8%, V 1-5%, Zr 1-3%, Mo 0.5-3%, Hf 1%, Y 0.01-0.5%, and Nb balance.

[0023] In the present application, Nb as the first main element provides the alloy with basic properties and performance; Ti element as the second main element is infinitely solid-solved with Nb and affects the lattice point array parameter, and increases the solid solubility of the solid solution to the remaining elements; the low content of Al element causes strong lattice distortion, and the high content of Al element forms a strengthening phase; the addition of V, Zr, Mo, Hf and other elements replaces the position of Nb element in the lattice, causing lattice distortion. After the introduction of rare earth Y micro-alloying, part of it is solid-solved into the alloy, and the part exceeding the solid solubility forms a second phase. In theory, the small part of Y solid-solved into the alloy replaces the remaining alloy elements, further causing lattice distortion; and the precipitated rare earth oxide phase is different from the alloy crystal structure, and a non-coherent interface is mainly formed between the two phases. When subjected to load at high temperature, the lattice distortion caused by rare earth Y micro-alloying hinders the movement of dislocations, and the second phase and grain refinement also strongly hinder the movement of dislocations.

[0024] Preferably, the lightweight Nb-Ti-Al-based alloy comprises, according to 100% of atomic percentage: Ti 36-38%, Al 4-8%, V 1-5%, Zr 1-3%, Mo 0.5-3%, Hf 1%, Y 0.01-0.2%, and Nb in the remainder.

[0025] The lightweight Nb-Ti-Al-based alloy comprises niobium-based solid solution grains, and the grain size decreases with the increase of the content of rare earth Y.

[0026] When the content of rare earth Y is 0.1 at.% and 0.2 at.%, the particle size of the niobium-based solid solution grains corresponds to 330.98 μm and 270.81 μm.

[0027] The second aspect of the present application provides a preparation method of a lightweight Nb-Ti-Al-based alloy micro-alloyed with rare earth Y, comprising the following steps: Ti, Al, V, Zr, Mo, Hf, Y and Nb are weighed according to atomic percentage to obtain raw materials; Al, Ti, Y, Zr, V, Mo, Hf and Nb raw materials are sequentially placed in a melting furnace according to the melting point from low to high, vacuum is extracted, and argon protection is filled to melt to obtain an alloy ingot; The alloy ingot is repeatedly melted for multiple times to obtain the lightweight Nb-Ti-Al-based alloy micro-alloyed with rare earth Y.

[0028] Before the raw materials are weighed, pretreatment is performed to remove surface contaminants and oxide layers.

[0029] Vacuum extraction is performed to 1×10 -3 Pa, and argon is filled to 20 KPa-50 KPa.

[0030] Repeated melting is performed for 4-6 times.

[0031] The purity of the raw material is 99.40-99.99%.

[0032] Exemplarily, a preparation method of a rare earth Y micro-alloyed light Nb-Ti-Al based alloy comprises the following steps: I. ingredient preparation: prepare raw materials according to the atomic percentage composition of each alloy component, all the raw materials are single elements, and the raw materials include Nb blocks (purity: 99.40 wt.%), Ti particles (purity: 99.99 wt.%), Al particles (purity: 99.99 wt.%), V particles (purity: 99.95 wt.%), Zr particles (purity: 99.9 wt.%), Hf blocks (purity: 99.95 wt.%), Mo particles (purity: 99.9 wt.%), and Y (purity: 99.9 wt.%). Before weighing, the Nb, V, Zr, Hf and Mo are subjected to decontamination powder washing, acid washing and alcohol washing; the Ti and Y are subjected to decontamination powder washing and alcohol washing; and the Al is subjected to decontamination powder washing, alkali washing and alcohol washing. The purpose of washing is to remove surface stains and oxide scales.

[0033] The light Nb-Ti-Al based alloy is composed of 36-38% of Ti, 4-8% of Al, 1-5% of V, 1-3% of Zr, 0.5-3% of Mo, 1% of Hf, 0.01-0.5% of Y and the balance of Nb in terms of atomic ratio. II. melting: the raw materials prepared in step I are stacked in a water-cooled copper crucible according to the melting point from low to high, and the stacking sequence is Al, Ti, Y, Zr, V, Hf, Mo and Nb in turn, the vacuum is extracted to a certain vacuum degree, then argon protection is performed, the melting current is increased to 800-1000 A, the melting is continued for 3-5 min under the condition of the melting current, and then the melting is ended, and a button ingot is obtained after cooling.

[0034] Specifically, after the raw materials are completely placed in the water-cooled copper crucible, the vacuum chamber is closed and vacuumed to 1.0*10 -3 Pa, and argon protection is performed to ensure that the alloy is not oxidized during the melting process. During the arc melting process, the melting voltage is kept below 20 V, and the melting current is gradually increased, with an interval of 50 A each time. After keeping a certain time at the maximum melting current each time, the melting current is slowly reduced to zero. The above melting operation is repeated five times to ensure the uniformity of the alloy composition.

[0035] The rare earth Y element added in the present application combines with a small amount of residual oxygen to form yttrium oxide during the melting process, thereby improving the purity of the alloy and reducing the content of oxygen and other elements. The purification of impurity elements at the grain boundary may promote the improvement of the grain boundary strength, and then improve the high temperature strength of the alloy.

[0036] The third aspect of this invention provides the application of a rare-earth Y microalloyed lightweight Nb-Ti-Al based alloy in high-temperature resistant structures.

[0037] It should be noted that, unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the reagents and materials used, unless otherwise specified, are all commercially available.

[0038] Example 1 A lightweight Nb-Ti-Al based alloy with rare earth Y microalloying is disclosed. The alloy comprises, by atomic percentage, 36% Ti, 5% Al, 3% V, 1% Zr, 1% Mo, 1% Hf, 0.01% Y, and the balance Nb. The preparation steps of this alloy are as follows: Step 1: Weigh the raw materials according to the above composition. The raw materials include Nb blocks (purity: 99.40 wt.%), Ti particles (purity: 99.99 wt.%), Al particles (purity: 99.99 wt.%), V particles (purity: 99.95 wt.%), Zr particles (purity: 99.9 wt.%), Hf blocks (purity: 99.95 wt.%), Mo particles (purity: 99.9 wt.%), and Y (purity: 99.9 wt.%). Before weighing, Nb, V, Zr, Hf, and Mo are washed with detergent powder + acid + alcohol; Ti and Y are washed with detergent powder + alcohol; and Al is washed with detergent powder + alkali + alcohol.

[0039] Step Two: Before arc melting, confirm that the cooling water and power supply are working properly and that the vacuum chamber is clean. After inspection, stack the raw materials prepared in Step One into the water-cooled copper crucible according to their melting points from low to high, in the following order: Al, Ti, Y, Zr, V, Hf, Mo, Nb. Specifically, to prevent Y from being blown away, stack Y among the Ti particles during material feeding. After closing the vacuum chamber, evacuate to a vacuum level of 1.0 × 10⁻⁶. -3 The pressure is maintained at 1.0 × 10⁻⁶ Pa for at least 10 hours. After confirming good pressure maintenance, argon gas is introduced for the first purging and the system is then evacuated again to 1.0 × 10⁻⁶ Pa. -3 Pa, then a second argon gas protection charge is applied. Before melting the alloy, the sponge titanium ingot is melted first to absorb oxygen. After oxygen absorption, the water-cooled copper crucible is rotated, and the alloy is melted sequentially. During the arc melting process, the melting voltage is kept below 20 V, and the melting current is gradually increased at 50 A intervals. Each time, the melting current is held at its maximum for a certain period of time, and then the melting current is slowly reduced until it is turned off. The above melting operation is repeated five times to ensure the uniformity of the alloy composition.

[0040] Step 3: Sample preparation. Samples are taken from the same location on alloy ingots with different compositions. Sampling is performed using an electrical discharge wire cutter. The high-temperature compressive strength sample is a cylindrical specimen with a diameter of 6 × 9 mm. The high-temperature compression test temperature is 1200 ℃, and the deformation rate is 0.01 s⁻¹. -1 The room temperature fracture toughness specimen is a rectangular sample of 30×5×2.5 mm, with a 2.5 mm long notch pre-made in the middle of the long side of the specimen.

[0041] Example 2 A lightweight Nb-Ti-Al based alloy with rare earth Y microalloying is disclosed. The alloy comprises, by atomic percentage, 37% Ti, 5% Al, 3% V, 1% Zr, 1% Hf, 1% Mo, 0.05% Y, and the balance Nb. The preparation steps of this alloy are as follows: Step 1: Weigh the raw materials according to the above composition. The raw materials include Nb blocks (purity: 99.40 wt.%), Ti particles (purity: 99.99 wt.%), Al particles (purity: 99.99 wt.%), V particles (purity: 99.95 wt.%), Zr particles (purity: 99.9 wt.%), Hf blocks (purity: 99.95 wt.%), Mo particles (purity: 99.9 wt.%), and Y (purity: 99.9 wt.%). Before weighing, Nb, V, Zr, Hf, and Mo are washed with detergent powder + acid + alcohol; Ti and Y are washed with detergent powder + alcohol; and Al is washed with detergent powder + alkali + alcohol.

[0042] Step Two: Before arc melting, confirm that the cooling water and power supply are working properly and that the vacuum chamber is clean. After inspection, stack the raw materials prepared in Step One into the water-cooled copper crucible according to their melting points from low to high, in the following order: Al, Ti, Y, Zr, V, Hf, Mo, Nb. Specifically, to prevent Y from being blown away, stack Y among the Ti particles during material feeding. After closing the vacuum chamber, evacuate to a vacuum level of 1.0 × 10⁻⁶. -3 The pressure is maintained at 1.0 × 10⁻⁶ Pa for at least 10 hours. After confirming good pressure maintenance, argon gas is introduced for the first purging and the system is then evacuated again to 1.0 × 10⁻⁶ Pa. -3 Pa, then a second argon gas protection charge is applied. Before melting the alloy, the sponge titanium ingot is melted first to absorb oxygen. After oxygen absorption, the water-cooled copper crucible is rotated, and the alloy is melted sequentially. During the arc melting process, the melting voltage is kept below 20 V, and the melting current is gradually increased at 50 A intervals. Each time, the melting current is held at its maximum for a certain period of time, and then the melting current is slowly reduced until it is turned off. The above melting operation is repeated five times to ensure the uniformity of the alloy composition.

[0043] Step 3: Sample preparation. Samples are taken from the same location on alloy ingots with different compositions. Sampling is performed using an electrical discharge wire cutter. The high-temperature compressive strength sample is a cylindrical specimen with a diameter of 6 × 9 mm. The high-temperature compression test temperature is 1200 ℃, and the deformation rate is 0.01 s⁻¹. -1 The room temperature fracture toughness specimen is a rectangular sample of 30×5×2.5 mm, with a 2.5 mm long notch pre-made in the middle of the long side of the specimen.

[0044] Example 3 A lightweight Nb-Ti-Al based alloy with rare earth Y microalloying is disclosed. The alloy comprises, by atomic percentage, 37% Ti, 6% Al, 3% V, 1% Zr, 1% Hf, 1% Mo, 0.1% Y, and the balance Nb. The preparation steps of this alloy are as follows: Step 1: Weigh the raw materials according to the above composition. The raw materials include Nb blocks (purity: 99.40 wt.%), Ti particles (purity: 99.99 wt.%), Al particles (purity: 99.99 wt.%), V particles (purity: 99.95 wt.%), Zr particles (purity: 99.9 wt.%), Hf blocks (purity: 99.95 wt.%), Mo particles (purity: 99.9 wt.%), and Y (purity: 99.9 wt.%). Before weighing, Nb, V, Zr, Hf, and Mo are washed with detergent powder + acid + alcohol; Ti and Y are washed with detergent powder + alcohol; and Al is washed with detergent powder + alkali + alcohol.

[0045] Step Two: Before arc melting, confirm that the cooling water and power supply are working properly and that the vacuum chamber is clean. After inspection, stack the raw materials prepared in Step One into the water-cooled copper crucible according to their melting points from low to high, in the following order: Al, Ti, Y, Zr, V, Hf, Mo, Nb. Specifically, to prevent Y from being blown away, stack Y among the Ti particles during material feeding. After closing the vacuum chamber, evacuate to a vacuum level of 1.0 × 10⁻⁶. -3 The pressure is maintained at 1.0 × 10⁻⁶ Pa for at least 10 hours. After confirming good pressure maintenance, argon gas is introduced for the first purging and the system is then evacuated again to 1.0 × 10⁻⁶ Pa. -3 Pa, then a second argon gas protection charge is applied. Before melting the alloy, the sponge titanium ingot is melted first to absorb oxygen. After oxygen absorption, the water-cooled copper crucible is rotated, and the alloy is melted sequentially. During the arc melting process, the melting voltage is kept below 20 V, and the melting current is gradually increased at 50 A intervals. Each time, the melting current is held at its maximum for a certain period of time, and then the melting current is slowly reduced until it is turned off. The above melting operation is repeated five times to ensure the uniformity of the alloy composition.

[0046] Step 3: Sample preparation. Samples are taken from the same location on alloy ingots with different compositions. Sampling is performed using an electrical discharge wire cutter. The high-temperature compressive strength sample is a cylindrical specimen with a diameter of 6 × 9 mm. The high-temperature compression test temperature is 1200 ℃, and the deformation rate is 0.01 s⁻¹. -1 The room temperature fracture toughness specimen is a rectangular sample of 30×5×2.5 mm, with a 2.5 mm long notch pre-made in the middle of the long side of the specimen.

[0047] Example 4 A lightweight Nb-Ti-Al based alloy with rare earth Y microalloying is disclosed. The alloy comprises, by atomic percentage, 37% Ti, 6% Al, 3% V, 1% Zr, 1% Hf, 1% Mo, 0.2% Y, and the balance Nb. The preparation steps of this alloy are as follows: Step 1: Weigh the raw materials according to the above composition. The raw materials include Nb blocks (purity: 99.40 wt.%), Ti particles (purity: 99.99 wt.%), Al particles (purity: 99.99 wt.%), V particles (purity: 99.95 wt.%), Zr particles (purity: 99.9 wt.%), Hf blocks (purity: 99.95 wt.%), Mo particles (purity: 99.9 wt.%), and Y (purity: 99.9 wt.%). Before weighing, Nb, V, Zr, Hf, and Mo are washed with detergent powder + acid + alcohol; Ti and Y are washed with detergent powder + alcohol; and Al is washed with detergent powder + alkali + alcohol.

[0048] Step Two: Before arc melting, confirm that the cooling water and power supply are working properly and that the vacuum chamber is clean. After inspection, stack the raw materials prepared in Step One into the water-cooled copper crucible according to their melting points from low to high, in the following order: Al, Ti, Y, Zr, V, Hf, Mo, Nb. Specifically, to prevent Y from being blown away, stack Y among the Ti particles during material feeding. After closing the vacuum chamber, evacuate to a vacuum level of 1.0 × 10⁻⁶. -3 The pressure is maintained at 1.0 × 10 Pa for at least 10 hours. After confirming good pressure maintenance, argon gas is introduced for the first purging and the system is then evacuated again to 1.0 × 10 Pa. -3 Pa, then a second argon gas protection charge is applied. Before melting the alloy, the sponge titanium ingot is melted first to absorb oxygen. After oxygen absorption, the water-cooled copper crucible is rotated, and the alloy is melted sequentially. During the arc melting process, the melting voltage is kept below 20 V, and the melting current is gradually increased at 50 A intervals. Each time, the melting current is held at its maximum for a certain period of time, and then the melting current is slowly reduced until it is turned off. The above melting operation is repeated five times to ensure the uniformity of the alloy composition.

[0049] Step 3: Sample preparation. Samples are taken from the same location on alloy ingots with different compositions. Sampling is performed using an electrical discharge wire cutter. The high-temperature compressive strength sample is a cylindrical specimen with a diameter of 6 × 9 mm. The high-temperature compression test temperature is 1200 ℃, and the deformation rate is 0.01 s⁻¹. -1 The room temperature fracture toughness specimen is a rectangular sample of 30×5×2.5mm, with a 2.5mm long notch pre-made in the middle of the long side of the specimen.

[0050] Comparative Example 1 A lightweight Nb-Ti-Al based alloy without rare-earth Y microalloying is disclosed. The alloy comprises, by atomic percentage, 36% Ti, 6% Al, 3% V, 1% Zr, 1% Hf, 1% Mo, and the balance Nb. The preparation steps of this alloy are as follows: Step 1: Weigh the raw materials according to the above composition. The raw materials include Nb blocks (purity: 99.40 wt.%), Ti particles (purity: 99.99 wt.%), Al particles (purity: 99.99 wt.%), V particles (purity: 99.95 wt.%), Zr particles (purity: 99.9 wt.%), Hf blocks (purity: 99.95 wt.%), Mo particles (purity: 99.9 wt.%), and Y (purity: 99.9 wt.%). Before weighing, Nb, V, Zr, Hf, and Mo are washed with detergent powder + acid + alcohol; Ti and Y are washed with detergent powder + alcohol; and Al is washed with detergent powder + alkali + alcohol.

[0051] Step Two: Before arc melting, confirm that the cooling water and power supply are working properly and that the vacuum chamber is clean. After inspection, stack the raw materials prepared in Step One into the water-cooled copper crucible according to their melting points from low to high, in the following order: Al, Ti, Y, Zr, V, Hf, Mo, Nb. Specifically, to prevent Y from being blown away, stack Y among the Ti particles during material feeding. After closing the vacuum chamber, evacuate to a vacuum level of 1.0 × 10⁻⁶. -3 The pressure is maintained at 1.0 × 10⁻⁶ Pa for at least 10 hours. After confirming good pressure maintenance, argon gas is introduced for the first purging and the system is then evacuated again to 1.0 × 10⁻⁶ Pa. -3 Pa, then a second argon gas protection charge is applied. Before melting the alloy, the sponge titanium ingot is melted first to absorb oxygen. After oxygen absorption, the water-cooled copper crucible is rotated, and the alloy is melted sequentially. During the arc melting process, the melting voltage is kept below 20 V, and the melting current is gradually increased at 50 A intervals. Each time, the melting current is held at its maximum for a certain period of time, and then the melting current is slowly reduced until it is turned off. The above melting operation is repeated five times to ensure the uniformity of the alloy composition.

[0052] Step 3: Sample Preparation: Specifically, samples are taken from the same locations on the alloy ingot. Sampling is performed using an electrical discharge wire cutter. The high-temperature compressive strength sample is a cylindrical specimen with a diameter of 6 × 9 mm. The high-temperature compression test temperature is 1200 ℃, and the deformation rate is 0.01 s⁻¹. -1 The room temperature fracture toughness specimen is a rectangular sample of 30×5×2.5 mm, with a 2.5 mm long notch pre-made in the middle of the long side of the specimen.

[0053] To illustrate the relevant properties of the rare earth Y microalloyed lightweight Nb-Ti-Al based alloy provided by the present invention, the accompanying drawings are provided.

[0054] The microstructure of Comparative Example 1 and Examples 1 to 4 are as follows Figure 1 As shown, the grain size distribution and average grain size characterization are as follows: Figure 2 As the rare earth element Y content increases, the alloy grains gradually become finer, which perfectly aligns with the original design intent of this invention. Meanwhile, as... Figure 1 As shown in Examples 3 and 4, second-phase particles precipitated in the alloy. This precipitation also creates a second-phase strengthening mechanism, improving the alloy's strength. Therefore, from a microstructural perspective, this invention, through the alloying of trace rare earth elements, induces alloy microstructure refinement and the precipitation of a second phase. Theoretically, this can result in the combined effect of both grain refinement strengthening and second-phase strengthening mechanisms, thereby improving the alloy's mechanical properties. Simultaneously, improved oxidation resistance is achieved through rapid oxide film formation and suppression of ion diffusion.

[0055] Figure 3 The values ​​shown are the high-temperature compressive strength values ​​for Comparative Example 1 and Examples 1 to 4. When the Y content is 0.05 at.%, the compressive strength of the alloy is slightly improved. The compression test temperature of the alloy in this invention is 1200 °C. At this temperature, the alloy exhibits an effect opposite to the Hall-Page effect, i.e., the positive correlation between strength and grain refinement fails. Therefore, its strength improvement is mainly related to the second phase. Figure 4 To compare the high-temperature oxidation weight gain values ​​of Examples 1 to 4, the addition of Y in Examples 1 to 4 of this invention resulted in a decrease in oxidation weight gain and an improvement in antioxidant properties.

[0056] Figure 5 The results were obtained by measuring the three-point bending test with pre-formed notches on alloys with different rare earth contents. K Q The main factor affecting room temperature fracture toughness is the grain size of the alloy. Except when the rare earth content is low, the grain refinement effect is not significant, leading to fluctuations in the alloy's fracture toughness value. Rare earth Y can significantly improve the fracture toughness of the alloy. As shown in Table 1 below, Examples 2 to 4 are compared with Comparative Example 1. K Q Increased by approximately 10 MPa·m 1 / 2Overall, this invention provides a second embodiment with improved high-temperature strength, enhanced room-temperature toughness, and improved high-temperature oxidation resistance.

[0057] This invention describes preferred embodiments and their effects. However, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to include both the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A lightweight Nb-Ti-Al based alloy with rare earth Y microalloying, characterized in that, The lightweight Nb-Ti-Al based alloy comprises Ti, Al, V, Zr, Mo, Hf, Y, and Nb, and based on an atomic percentage of 100%, includes: Ti 36-38%, Al 4-8%, V 1-5%, Zr 1-3%, Mo 0.5-3%, Hf 1%, Y 0.01-0.5%, and Nb as the balance.

2. The lightweight Nb-Ti-Al based alloy with rare earth Y microalloying according to claim 1, characterized in that, The lightweight Nb-Ti-Al based alloy, based on an atomic percentage of 100%, comprises: Ti 36-38%, Al 4-8%, V 1-5%, Zr 1-3%, Mo 0.5-3%, Hf 1%, Y 0.01-0.2%, with Nb as the balance.

3. The lightweight Nb-Ti-Al based alloy with rare earth Y microalloying according to claim 1, characterized in that, The lightweight Nb-Ti-Al based alloy comprises niobium-based solid solution grains, the grain size of which decreases as the rare earth Y content increases.

4. The lightweight Nb-Ti-Al based alloy with rare earth Y microalloying according to claim 3, characterized in that, When the rare earth Y content is 0.1 at.% and 0.2 at.%, the corresponding grain sizes of the niobium-based solid solution are 330.98 μm and 270.81 μm.

5. A method for preparing a lightweight Nb-Ti-Al based alloy with rare earth Y microalloying as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Weigh out Ti, Al, V, Zr, Mo, Hf, Y, and Nb according to atomic percentage to obtain the raw materials; According to the melting point from low to high, raw materials Al, Ti, Y, Zr, V, Mo, Hf and Nb are stacked into the melting furnace. After vacuuming, argon gas is introduced for protection and melting to obtain alloy ingots. After repeatedly melting the alloy ingot, a lightweight Nb-Ti-Al based alloy with rare earth Y micro-alloying is obtained.

6. The method for preparing a lightweight Nb-Ti-Al based alloy with rare earth Y microalloying according to claim 5, characterized in that, The raw materials are pretreated before weighing to remove surface contaminants and oxide layers.

7. The method for preparing a lightweight Nb-Ti-Al based alloy with rare earth Y microalloying according to claim 5, characterized in that, Vacuum up to 1×10 -3 Pa, fill with argon gas to 20 kPa–50 kPa.

8. The method for preparing a lightweight Nb-Ti-Al based alloy with rare earth Y microalloying according to claim 5, characterized in that, Repeat the melting process 4 to 6 times.

9. The method for preparing a lightweight Nb-Ti-Al based alloy with rare earth Y microalloying according to claim 5, characterized in that, The purity of the raw materials is 99.40~99.99%.

10. The application of a lightweight Nb-Ti-Al based alloy with rare earth Y microalloying as described in any one of claims 1 to 4 in a high-temperature resistant structure.

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