A light-heavy mixed rare earth added Nb-Si-based alloy with both strength and toughness and a preparation method thereof

Abstract

The application relates to the technical field of metal materials, in particular to a Nb-Si-based alloy with strength and toughness by adding light and heavy rare earths and a preparation method thereof. The technical key points are as follows: the ultrahigh-temperature alloy is composed of Nb, Si, Zr, Al, light rare earth X and heavy rare earth Y; the atomic percentage content of each element of the ultrahigh-temperature alloy is as follows: Si: 12-20%, Zr: 18-22%, Al: 2-4%, X: 0.2-2%, Y: 0.2-3%, the balance being Nb, and the sum of the atomic percentage contents of the elements is 100%; the light rare earth X is selected from at least one of Ce, Sm and Nd, and the heavy rare earth Y is selected from at least one of Sc, Tb and Dy; the eutectic structure is obviously refined, the phase distribution is optimized, and high-melting-point oxides are generated in situ, so that the room-temperature fracture toughness and deformation resistance of the alloy are simultaneously improved under the premise of not sacrificing high-temperature performance.

Description

Technical Field

[0001] This invention relates to the field of metallic materials technology, specifically to an Nb-Si based alloy with both strength and toughness achieved by adding a mixture of light and heavy rare earth elements, and its preparation method. Background Technology

[0002] New materials are a key foundation for the development of aerospace technology, especially in the field of engines, where the demand for high-temperature resistant structural materials is extremely urgent. The thrust-to-weight ratio target for next-generation aero-engines needs to be achieved, which places higher demands on the operating temperature resistance of their hot-end components. Nb-Si in-situ composites, due to their excellent high-temperature mechanical properties, are considered potential candidates to replace existing nickel-based superalloys. However, the high volume fraction of silicides in this material's microstructure exhibits intrinsic brittleness, limiting its practical engineering applications. In recent years, research has mainly focused on improving its room-temperature toughness through alloying methods, but the performance levels achieved so far still fall significantly short of the industrial application threshold (fracture toughness KQ > 20 MPa·m¹ / ²).

[0003] Rare earth elements, due to their high chemical reactivity and strong affinity for oxygen, have shown significant potential in material deoxidation and toughening. Industrially, rare earth elements are classified into light rare earths (La, Ce, Pr, Nd, Pm, Sm, Eu) and heavy rare earths (Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). As microalloying elements, rare earths have demonstrated significant modification effects in lightweight alloy systems such as aluminum, magnesium, and titanium alloys, providing a reference for their application in other alloy systems. Existing research indicates that introducing a single type of rare earth element (such as light rare earth Ce or heavy rare earth Y) into Nb-Si based alloys can improve performance through different mechanisms: light rare earths tend to form oxides at the interface to suppress internal oxidation, while heavy rare earths may regulate the matrix phase distribution through solid solution effects. However, existing research has two key limitations: on the one hand, the performance improvement path is singular, and optimization for strength or toughness often comes at the expense of another performance, making it difficult to overcome the contradiction between strength and toughness; on the other hand, the interaction between different rare earth elements and their coupling effects on multi-scale structures (such as eutectic morphology and phase interface characteristics) have not yet been clearly established.

[0004] Therefore, there is an urgent need to develop a new alloy design strategy that can simultaneously address the room-temperature brittleness and high-temperature stability issues of Nb-Si alloys without significantly increasing process complexity, in order to meet the stringent requirements of engineering applications for comprehensive performance. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention provides an Nb-Si based alloy with both strength and toughness achieved by adding a mixture of light and heavy rare earth elements, and its preparation method. This effectively solves the problem that the poor strength and toughness of existing Nb-Si based alloys affect subsequent processing and assembly.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides an Nb-Si ultra-high temperature alloy with both strength and toughness by adding a mixture of light and heavy rare earth elements, wherein the ultra-high temperature alloy is composed of Nb, Si, Zr, Al, light rare earth element X and heavy rare earth element Y.

[0008] The atomic percentage content of each element in the super-high temperature alloy is as follows: Si: 12-20%, Zr: 18-22%, Al: 2-4%, X: 0.2-2%, Y: 0.2-3%, with the balance being Nb, and the sum of the atomic percentage content of each element is 100%.

[0009] The light rare earth element X is selected from Ce, Sm and Nd, and the heavy rare earth element Y is selected from Sc, Tb and Dy.

[0010] Furthermore, the alloy, by atomic percentage, has the following composition and content: Nb 61%, Si 16%, Zr 20%, Al 2%, X 0.2%, and Y 0.8%.

[0011] Furthermore, the composition and content of the ultra-high temperature alloy, by atomic percentage, are: 61% Nb, 16% Si, 20% Zr, 2% Al, 0.5% X and 0.5% Y.

[0012] Furthermore, the composition and content of the ultra-high temperature alloy, by atomic percentage, are as follows: Nb 61%, Si 16%, Zr 20%, Al 2%, X 0.8% and Y 0.2%.

[0013] Furthermore, the composition and content of the ultra-high temperature alloy, by atomic percentage, are as follows: Nb 60.7%, Si 16%, Zr 20%, Al 2%, X 0.8% and Y 0.5%.

[0014] Furthermore, the composition and content of the ultra-high temperature alloy, by atomic percentage, are as follows: Nb 61.3%, Si 16%, Zr 20%, Al 2%, X 0.2% and Y 0.5%.

[0015] Furthermore, the composition and content of the ultra-high temperature alloy, by atomic percentage, are: 59% Nb, 16% Si, 20% Zr, 2% Al, 1% X and 2% Y.

[0016] Furthermore, the composition and content of the ultra-high temperature alloy, by atomic percentage, are: 57% Nb, 16% Si, 20% Zr, 2% Al, 2% X and 3% Y.

[0017] Furthermore, the composition and content of the ultra-high temperature alloy, by atomic percentage, are as follows: Nb 59%, Si 16%, Zr 20%, Al 2%, X 1.5% and Y 1.5%.

[0018] Furthermore, the superheated alloy has a compressive strength of 1841 MPa and a fracture toughness of 10.07 MPa·m. 1 / 2 .

[0019] In a second aspect, the present invention also provides a method for preparing a Nb-Si superalloy with both strength and toughness by adding a mixture of light and heavy rare earth elements as described in the first aspect, the preparation method comprising the following steps:

[0020] S1. Weigh out the raw materials of Nb, Si, Zr, Al, light rare earth element X and heavy rare earth element Y according to the following atomic percentage ratio: Si accounts for 12-20%, Zr accounts for 18-22%, Al accounts for 2-4%, light rare earth element X accounts for 0-2%, heavy rare earth element Y accounts for 0-3%, and the balance is Nb, and the sum of the atomic percentages of each component is 100%;

[0021] S2. Place the particles of light rare earth element X and heavy rare earth element Y in a vacuum drying oven for baking treatment;

[0022] S3. In the main crucible of the electric arc melting furnace, Si, X, Y, Al, Zr and Nb raw materials are loaded in order from bottom to top, and 70-90 g of sponge titanium is loaded in the secondary crucible.

[0023] S4. After evacuating the furnace containing the raw materials, fill it with high-purity argon as a protective atmosphere and carry out arc melting. After melting is completed, cool the furnace to obtain button ingot samples.

[0024] S5. The button ingot sample is repeatedly melted 6-8 times under an argon protective atmosphere, and then cooled to obtain the Nb-Si ultra-high temperature alloy.

[0025] Furthermore, in step S2, the baking temperature is 150-200℃ and the time is 1-2 hours.

[0026] Furthermore, in step S4, the vacuum level inside the furnace cavity is increased to a value better than 5 × 10⁻⁶. -2 Pa; the current for the electric arc melting is 300-500 A, and the melting time for each melting is 60-120 seconds.

[0027] The technical solution provided by this invention has the following advantages compared with the known prior art:

[0028] 1. The alloy prepared by adding light and heavy rare earth elements contains a new oxide phase in its microstructure. Under high temperature conditions, light rare earth elements X and O react and precipitate first, forming oxides which are beneficial to purifying the microstructure. The oxides serve as heterogeneous nucleation sites, which can refine silicides. In addition, heavy rare earth elements Y are dissolved into the matrix to strengthen the matrix, thereby achieving the purpose of improving the strength and toughness of Nb-Si.

[0029] 2. The alloy of the present invention is prepared by vacuum non-consumable melting in a water-cooled copper crucible, which is low in cost, simple in process, and short in preparation cycle. Oxide precipitation and fine Nbss / Nb5Si3 eutectic structure were observed in the microstructure.

[0030] 3. The alloy prepared by this invention has improved comprehensive properties, with strong strength and toughness, and broadens the window for rare earth elements to improve the performance of Nb-Si alloys. It is a Nb-Si based alloy with great development potential. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0032] Figure 1 The images show the XRD patterns of the Nb-16Si-20Zr-2Al-0.2Ce-0.8Sc alloy of Example 1 and the comparative Nb-16Si-20Zr-2Al alloy of the present invention.

[0033] Figure 2 The images are scanning electron microscope (SEM) images, where (a) is the SEM image of the Nb-16Si-20Zr-2Al-0.8Ce-0.5Sc alloy of Example 1, and (b) is the SEM image of the Nb-16Si-20Zr-2Al alloy of the comparative example.

[0034] Figure 3 The graphs show the compressive properties of the alloys prepared in Examples 1-5 and the comparative examples.

[0035] Figure 4 The figures show the fracture toughness test results of the alloys prepared in Examples 1-5 and the comparative examples. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0037] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail. The terms “comprising,” “including,” “having,” “containing,” etc., as used herein are open-ended terms, meaning that they include but are not limited to. Unless the context clearly indicates otherwise, the expressions “a” and “an” as used herein include plural references. It should be noted that “first,” “second,” etc., are used merely for convenience of description and distinction and should not be construed as indicating or implying relative importance. The term “about” as used herein indicates a range of ±20% of the following numerical value. In some embodiments, the term “about” indicates a range of ±10% of the following numerical value. In some embodiments, the term “about” indicates a range of ±5% of the following numerical value. The invention is further described below with reference to embodiments.

[0038] Example: Refer to Figures 1 to 4 .

[0039] This invention provides a Nb-Si superheated alloy with both strength and toughness, incorporating a mixture of light and heavy rare earth elements. The superheated alloy is composed of Nb, Si, Zr, Al, light rare earth element X, and heavy rare earth element Y. The atomic percentage content of each element in the superheated alloy is as follows: Si: 12-20%, Zr: 18-22%, Al: 2-4%, X: 0.2-2%, Y: 0.2-3%, with the balance being Nb, and the sum of the atomic percentage content of each element is 100%. The light rare earth element X is selected from at least one of Ce, Sm, and Nd, and the heavy rare earth element Y is selected from at least one of Sc, Tb, and Dy.

[0040] This invention introduces light rare earth elements (such as Ce, Sm, and Pr) into Nb-Si ultra-high temperature alloys, which can form oxides at the interface to slow down the internal oxidation rate, thereby simultaneously improving the mechanical properties and oxidation resistance of the alloy. In addition, the addition of trace amounts of heavy rare earth elements can promote the continuous distribution of niobium-based solid solution (Nbss) and optimize the toughness of the alloy.

[0041] This invention introduces light and heavy rare earth microalloying into Nb-Si alloys, which significantly refines the eutectic structure, optimizes the phase distribution, and generates high-melting-point oxides in situ. Thus, without sacrificing high-temperature performance, it simultaneously improves the room-temperature fracture toughness (KQ > 20 MPa·m¹ / ²) and deformation resistance (strength) of the alloy, breaking through the technical bottleneck of traditional Nb-Si alloys where it is difficult to achieve both strength and toughness.

[0042] The method for preparing the Nb-Si ultra-high temperature alloy of the present invention is as follows:

[0043] (1) Weigh the raw materials Nb, Si, Zr, Al, Ce and Sc according to the above atomic ratio. The morphology and purity of the raw materials used must meet the following requirements: Nb: 2-9 mm irregular flakes with a purity of 99.95%; Si: 1-3 mm particles with a purity of 99.95%; Zr: sponge zirconium with a purity of 99.5%; Sc: particles with a purity of 99.9%; Al and Ce: φ4×4 mm particles with a purity of 99.95%.

[0044] (2) Surface pretreatment of raw materials: For Ce particles of light rare earth element and Sc particles of heavy rare earth element, place the accurately proportioned Ce and Sc particles in a vacuum baking oven and bake at 200-300℃ for 3-6 hours to remove the oxide scale and impurities on their surface.

[0045] (3) Pretreatment of oxygen-absorbing sponge titanium: First, descaling is performed by polishing with 380# or 600# SiC sandpaper; then, the first ultrasonic cleaning is performed in acetone medium at a power of 70-130W and a frequency of 15-40KHz for 10-20 minutes; finally, the second ultrasonic cleaning is performed in anhydrous ethanol medium at a power of 120-170W and a frequency of 40-60KHz for 5-10 minutes, and then it is dried.

[0046] (4) Place the raw materials in the main crucible of the electric arc furnace in the order of Al, Sc, Ce, Si, Zr, Nb, and place 70-90g of sponge titanium in the auxiliary crucible. Before melting, evacuate the furnace cavity to 3×10-3Pa, then fill it with high-purity argon to -0.04MPa, and then ignite the arc for melting. After ignition, the current range is 0-600A, and the circulating cooling water flow rate is 1-7m / s. During melting, first melt the sponge zirconium in the auxiliary crucible to consume the residual oxygen in the furnace to prevent subsequent oxidation, and then melt the raw materials. Keep it in a molten state for 30s, and after cooling, obtain the button ingot sample.

[0047] (5) To ensure the high uniformity of the alloy composition, the following operations were performed during the melting process: First, the button ingots were flipped and melted again using the robotic arm built into the furnace, and this process was repeated 6 times; then, during the cooling stage of the last melting, the cooling process was controlled by reducing the current at a rate of 60A / 15s. After the above treatment, a Nb-16Si-20Zr-2Al-0.2Ce-0.8Sc alloy with uniform structure and excellent performance was finally obtained.

[0048] In step (4) above, a non-consumable vacuum arc melting furnace is used for melting, the melting current is 150A to 600A, the current decrease rate during the cooling stage is 40A / 10s, and the flow rate of the circulating cooling water is 2m / s to 7m / s.

[0049] In step (4) above, vacuum melting is carried out under the following conditions: the vacuum degree of the furnace cavity is 2×10-3Pa-4×10-3Pa, the melting protective gas pressure is 0.05MPa-0.6MPa, and the pressure-holding gas is high-purity argon.

[0050] Example 1

[0051] This embodiment provides a Nb-Si ultra-high temperature alloy with both strength and toughness, which incorporates a mixture of light and heavy rare earth elements. The alloy's composition and content by atomic percentage are as follows: Nb 61%, Si 16%, Zr 20%, Al 2%, X 0.2%, and Y 0.8%, with light rare earth X being Ce and heavy rare earth Y being Sc, and the sum of the atomic percentages of each element being 100%; the composition formula is Nb-16Si-20Zr-2Al-0.2X-0.8Y.

[0052] The method for preparing the ultra-high temperature alloy in this embodiment is as follows:

[0053] Its preparation method is as follows:

[0054] (1) Weigh the raw materials Nb, Si, Zr, Al, Ce and Sc according to the above atomic ratio. The morphology and purity of the raw materials used must meet the following requirements: Nb: 2-9 mm irregular flakes with a purity of 99.95%; Si: 1-3 mm particles with a purity of 99.95%; Zr: sponge zirconium with a purity of 99.5%; Sc: particles with a purity of 99.9%; Al and Ce: φ4×4 mm particles with a purity of 99.95%.

[0055] (2) Surface pretreatment of raw materials: For Ce particles of light rare earth element and Sc particles of heavy rare earth element, place the accurately proportioned Ce and Sc particles in a vacuum baking oven and bake at 200-300℃ for 3-5 hours to remove the oxide scale and impurities on their surface.

[0056] (3) Pretreatment of oxygen-absorbing sponge titanium: First, polish it with 380# or 600# SiC sandpaper; then, perform the first ultrasonic cleaning for 8 minutes in acetone medium with 120W power and 40KHz frequency; finally, perform the second ultrasonic cleaning for 3 minutes in anhydrous ethanol medium with 140W power and 50KHz frequency.

[0057] (4) Place the raw materials in the main crucible of the electric arc furnace in the order of Al, Sc, Ce, Si, Zr, Nb, and simultaneously place 70-90g of sponge titanium in the auxiliary crucible. Before melting, evacuate the furnace cavity to 3×10⁻⁶. -3 The pressure was increased to -0.04 MPa by adding high-purity argon gas, followed by arc ignition and melting. After arc ignition, the current range was 150 A to 580 A, and the circulating cooling water flow rate was 1 m / s. During melting, the sponge zirconium in the auxiliary crucible was melted first to consume the residual oxygen in the furnace and prevent subsequent oxidation. Then the raw materials were melted and kept in a molten state for 30 seconds. After cooling, button ingot samples were obtained.

[0058] (5) To ensure the high uniformity of the alloy composition, the following operations were performed during the melting process: First, the button ingots were flipped and melted again using the robotic arm built into the furnace, and this process was repeated 6 times; then, during the cooling stage of the last melting, the cooling process was controlled by reducing the current at a rate of 60A / 15s. After the above treatment, a Nb-16Si-20Zr-2Al-0.2Ce-0.8Sc alloy with uniform structure and excellent performance was finally obtained.

[0059] In step (4) above, a non-consumable vacuum arc melting furnace is used for melting, the melting current is 150A to 600A, the current decrease rate during the cooling stage is 40A / 10s, and the flow rate of the circulating cooling water is 2m / s to 7m / s.

[0060] In step (4) above, vacuum melting is carried out under the following conditions: the vacuum degree of the furnace cavity is 2×10 -3 Pa-4×10 - 3 Pa, the smelting protective gas pressure is 0.05MPa-0.6MPa, and the pressure-holding gas is high-purity argon.

[0061] Example 2

[0062] This embodiment provides an Nb-Si ultra-high temperature alloy with both strength and toughness by adding a mixture of light and heavy rare earth elements, where the light rare earth element X is Ce and the heavy rare earth element Y is Sc.

[0063] The difference from Example 1 is that the Nb-Si super-high temperature alloy of this example has the following composition and content by atomic percentage: Nb is 61%, Si is 16%, Zr is 20%, Al is 2%, X is 0.5% and Y is 0.5%, and the sum of the atomic percentages of each element is 100%; the composition formula is Nb-16Si-20Zr-2Al-0.5X-0.5Y.

[0064] The preparation method of Nb-Si ultra-high temperature alloy in this embodiment is the same as that in Example 1, that is, after weighing raw materials, surface pretreatment, charging and melting, and repeated melting and homogenization treatment, Nb-16Si-20Zr-2Al-0.5Ce-0.5Sc alloy is finally obtained.

[0065] Example 3

[0066] This embodiment provides an Nb-Si ultra-high temperature alloy with both strength and toughness by adding a mixture of light and heavy rare earth elements, where the light rare earth element X is Ce and the heavy rare earth element Y is Sc.

[0067] The difference from Example 1 is that the Nb-Si super-high temperature alloy in this example has the following composition and content by atomic percentage: Nb is 61%, Si is 16%, Zr is 20%, Al is 2%, X is 0.8% and Y is 0.2%, and the sum of the atomic percentages of each element is 100%; the composition formula is Nb-16Si-20Zr-2Al-0.8X-0.2Y.

[0068] The preparation method of the Nb-Si ultra-high temperature alloy in this embodiment is the same as that in Example 1, and the Nb-16Si-20Zr-2Al-0.8Ce-0.2Sc alloy is finally obtained.

[0069] Example 4

[0070] This embodiment provides an Nb-Si ultra-high temperature alloy with both strength and toughness by adding a mixture of light and heavy rare earth elements, where the light rare earth element X is Ce and the heavy rare earth element Y is Sc.

[0071] The difference from Example 1 is that the Nb-Si super-high temperature alloy in this example has the following composition and content by atomic percentage: Nb is 60.7%, Si is 16%, Zr is 20%, Al is 2%, X is 0.8% and Y is 0.5%, and the sum of the atomic percentages of each element is 100%; the composition formula is Nb-16Si-20Zr-2Al-0.8X-0.5Y.

[0072] The preparation method of the Nb-Si ultra-high temperature alloy in this embodiment is the same as that in Example 1, and the Nb-16Si-20Zr-2Al-0.8Ce-0.5Sc alloy is finally obtained.

[0073] Example 5

[0074] This embodiment provides an Nb-Si ultra-high temperature alloy with both strength and toughness by adding a mixture of light and heavy rare earth elements, where the light rare earth element X is Ce and the heavy rare earth element Y is Sc.

[0075] The difference from Example 1 is that the Nb-Si super-high temperature alloy of this example has the following composition and content by atomic percentage: Nb is 61.3%, Si is 16%, Zr is 20%, Al is 2%, X is 0.2% and Y is 0.5%, and the sum of the atomic percentages of each element is 100%; the composition formula is Nb-16Si-20Zr-2Al-0.2X-0.5Y.

[0076] The preparation method of the Nb-Si ultra-high temperature alloy in this embodiment is the same as that in Example 1, and the Nb-16Si-20Zr-2Al-0.2Ce-0.5Sc alloy is finally obtained.

[0077] Comparative Example

[0078] The difference between this comparative Nb-Si alloy and Example 1 is that the composition of the Nb-Si ultra-high temperature alloy is set to 62% Nb, 16% Si, 20% Zr and 2% Al by atomic percentage.

[0079] The preparation method is the same as in Example 1, and an alloy of Nb-16Si-20Zr-2Al is obtained.

[0080] Experimental Procedure and Analysis:

[0081] The alloy samples obtained in this invention were mechanically polished and then subjected to phase analysis using X-ray diffraction (XRD, Panalytic, X'PERT) at a constant scanning speed of 7° / min within an angle range of 20°-90° (2θ). Figure 1 The figure shows the XRD patterns of the Nb-16Si-20Zr-2Al-0.2Ce-0.8Sc alloy prepared in Example 1 and the Nb-16Si-20Zr-2Al alloy prepared in the comparative example. In the figure, A represents the Nb-16Si-20Zr-2Al alloy, B represents the Nb-16Si-20Zr-2Al-0.2Ce-0.8Sc alloy, and the phases in the figure are labeled as follows: ● is Nbss, ◇ is β-Nb5Si3, ◆ is γ-Nb5Si3, ☆ is Ce2O3, where X represents the alloying element that substitutes for Nb. Figure 1As shown, in the Nb-16Si-20Zr-2Al alloy prepared in Comparative Example 1, characteristic diffraction peaks of three phases—Nbss (JCPDS 34-0370), γ-(Nb,X)5Si3 (JCPDS 04-010-7074), and β-(Nb,X)5Si3 (JCPDS 30-0875)—were detected. In the Nb-16Si-20Zr-2Al-0.2Ce-0.8Sc alloy prepared according to Example 1, in addition to the aforementioned phases, characteristic diffraction peaks of a new phase, Ce2O3 (JCPDS 23-1048), were also observed. This indicates that after the addition of Ce and Sc elements, the alloy's constituent phases are composed of Nbss, γ-(Nb,X)5Si3, β-(Nb,X)5Si3, and Ce2O3.

[0082] Figure 2 The images show the microstructures obtained by scanning electron microscopy (SEM), with (a) being the SEM image of the Nb-16Si-20Zr-2Al-0.8Ce-0.5Sc alloy of Example 1, and (b) being the SEM image of the comparative Nb-16Si-20Zr-2Al alloy. In both alloys prepared according to the embodiments, a large amount of Nbss / Nb5Si3 eutectic structure was observed. The SEM image of the Nb-16Si-20Zr-2Al alloy shows the presence of coarse silicides, which lead to a decrease in alloy toughness. The SEM image of the Nb-16Si-20Zr-2Al-0.2Ce-0.8Sc alloy shows a microstructure composed of a finer and continuous Nbss phase and an Nbss / (Nb,X)5Si3 eutectic, with a small amount of bright white Ce2O3 phase distributed near the silicides. The formation of this microstructure is attributed to the solid solution strengthening effect of Sc and the fact that Ce2O3, as a heterogeneous nucleation core, promotes microstructure refinement, thereby jointly improving the fracture toughness of the alloy.

[0083] The compressive performance test curves of the alloys prepared in Examples 1-5 and the comparative examples are shown below. Figure 3As shown, 1 is Nb-16Si-20Zr-2Al; 2 is Nb-16Si-20Zr-2Al-0.8Ce-0.5Sc; 3 is Nb-16Si-20Zr-2Al-0.5Ce-0.5Sc; 4 is Nb-16Si-20Zr-2Al-0.2Ce-0.8Sc; 5 is Nb-16Si-20Zr-2Al-0.8Ce-0.2Sc; and 6 is Nb-16Si-20Zr-2Al-0.2Ce-0.5Sc. The room temperature deformation resistance of the Nb-16Si-20Zr-2Al alloy prepared in Comparative Example 1 is 1642 MPa. As can be seen from the figure, the room temperature deformation resistance of the alloys prepared in Examples 1-5 is improved after composition optimization. Among them, the room temperature deformation resistance of the Nb-16Si-20Zr-2Al-0.2Ce-0.8Sc alloy reached 1713 MPa, the room temperature deformation resistance of the Nb-16Si-20Zr-2Al-0.5Ce-0.5Sc alloy was 1738 MPa, the room temperature deformation resistance of the Nb-16Si-20Zr-2Al-0.8Ce-0.2Sc alloy was 1708 MPa, and the room temperature deformation resistance of the Nb-16Si-20Zr-2Al-0.8Ce-0.5Sc alloy was 1723 MPa. The room temperature deformation resistance of the Nb-16Si-20Zr-2Al-0.2Ce-0.5Sc alloy prepared in Example 5 was 1841 MPa, which is 11.5% higher than that of the comparative Nb-16Si-20Zr-2Al alloy.

[0084] The fracture toughness test results of the Nb-Si-Zr-Al-Ce-Sc and Nb-Si-Zr-Al alloys prepared in Examples 1-5 and the comparative examples are as follows: Figure 4 As shown. According to the formula, it can be calculated that...

[0085] ;

[0086] ;

[0087] Among them, P Q The maximum load is represented by B, the specimen thickness is S, the span is w, the specimen width is a, and the notch length is a / w = 0.5. The fracture toughness KQ value of the Nb-16Si-20Zr-2Al alloy prepared in the comparative example is 7.32 MPa·m. 1 / 2 After composition optimization, the toughness of the alloys prepared in Examples 1-5 was significantly improved. Specifically, the fracture toughness KQ value of the Nb-16Si-20Zr-2Al-0.2Ce-0.8Sc alloy in Example 1 was 13.12 MPa·m. 1 / 2Compared to the comparative Nb-16Si-20Zr-2Al alloy, the KQ value of the Nb-16Si-20Zr-2Al-0.5Ce-0.5Sc alloy in Example 2 was improved by 69%, and the KQ value was 9.4 MPa·m. 1 / 2 The KQ value of the Nb-16Si-20Zr-2Al-0.8Ce-0.2Sc alloy in Example 3 is 8.85 MPa·m. 1 / 2 The KQ value of the Nb-16Si-20Zr-2Al-0.8Ce-0.5Sc alloy in Example 4 is 7.76 MPa·m. 1 / 2 The KQ value of the Nb-16Si-20Zr-2Al-0.2Ce-0.5Sc alloy in Example 5 is 10.07 MPa·m. 1 / 2 .

[0088] In some embodiments, the composition and content of the ultra-high temperature alloy, based on atomic percentage, may be: 59% Nb, 16% Si, 20% Zr, 2% Al, 1% X and 2% Y, and the preparation method is the same as in Example 1.

[0089] In some embodiments, the composition and content of the ultra-high temperature alloy, based on atomic percentage, may be: 57% Nb, 16% Si, 20% Zr, 2% Al, 2% X and 3% Y, and the preparation method is the same as in Example 1.

[0090] In some embodiments, the composition and content of the ultra-high temperature alloy, by atomic percentage, may be: 59% Nb, 16% Si, 20% Zr, 2% Al, 1.5% X and 1.5% Y, and the preparation method is the same as in Example 1.

[0091] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Nb-Si ultra-high temperature alloy with both strength and toughness, incorporating a mixture of light and heavy rare earth elements, characterized in that, The ultra-high temperature alloy is composed of Nb, Si, Zr, Al, light rare earth X and heavy rare earth Y. The atomic percentage content of each element in the super-high temperature alloy is as follows: Si: 12-20%, Zr: 18-22%, Al: 2-4%, X: 0.2-2%, Y: 0.2-3%, with the balance being Nb, and the sum of the atomic percentage content of each element is 100%. The light rare earth element X is selected from Ce, Sm and Nd, and the heavy rare earth element Y is selected from Sc, Tb and Dy.

2. The Nb-Si ultra-high temperature alloy with both strength and toughness achieved by adding a mixture of light and heavy rare earth elements according to claim 1, characterized in that, The alloy, by atomic percentage, has the following composition and content: 61% Nb, 16% Si, 20% Zr, 2% Al, 0.2% X, and 0.8% Y.

3. The Nb-Si ultra-high temperature alloy with both strength and toughness achieved by adding a mixture of light and heavy rare earth elements according to claim 1, characterized in that, The ultra-high temperature alloy, by atomic percentage, has the following composition and content: Nb 61%, Si 16%, Zr 20%, Al 2%, X 0.5% and Y 0.5%.

4. The Nb-Si ultra-high temperature alloy with both strength and toughness achieved by adding a mixture of light and heavy rare earth elements according to claim 1, characterized in that, The ultra-high temperature alloy, by atomic percentage, has the following composition and content: Nb 61%, Si 16%, Zr 20%, Al 2%, X 0.8%, and Y 0.2%.

5. The Nb-Si ultra-high temperature alloy with both strength and toughness achieved by adding a mixture of light and heavy rare earth elements according to claim 1, characterized in that, The ultra-high temperature alloy, by atomic percentage, has the following composition and content: Nb 60.7%, Si 16%, Zr 20%, Al 2%, X 0.8%, and Y 0.5%.

6. The Nb-Si ultra-high temperature alloy with both strength and toughness achieved by adding a mixture of light and heavy rare earth elements according to claim 1, characterized in that, The ultra-high temperature alloy, by atomic percentage, has the following composition and content: Nb 61.3%, Si 16%, Zr 20%, Al 2%, X 0.2% and Y 0.5%.

7. The Nb-Si ultra-high temperature alloy with both strength and toughness achieved by adding a mixture of light and heavy rare earth elements according to claim 1, characterized in that, The ultra-high temperature alloy, by atomic percentage, has the following composition and content: Nb 59%, Si 16%, Zr 20%, Al 2%, X 1%, and Y 2%.

8. The Nb-Si ultra-high temperature alloy with both strength and toughness achieved by adding a mixture of light and heavy rare earth elements according to claim 1, characterized in that, The ultra-high temperature alloy, by atomic percentage, has the following composition and content: Nb 57%, Si 16%, Zr 20%, Al 2%, X 2%, and Y 3%.

9. A Nb-Si ultra-high temperature alloy with both strength and toughness achieved by adding a mixture of light and heavy rare earth elements according to claim 1, characterized in that, The superheated alloy has a compressive strength of 1841 MPa and a fracture toughness of 10.07 MPa·m. 1 / 2 .

10. A method for preparing a Nb-Si ultra-high temperature alloy with both strength and toughness by adding a mixture of light and heavy rare earth elements as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: S1. Weigh out the raw materials of Nb, Si, Zr, Al, light rare earth element X and heavy rare earth element Y according to the following atomic percentage ratio: Si accounts for 12-20%, Zr accounts for 18-22%, Al accounts for 2-4%, light rare earth element X accounts for 0-2%, heavy rare earth element Y accounts for 0-3%, and the balance is Nb, and the sum of the atomic percentages of each component is 100%; S2. Place the particles of light rare earth element X and heavy rare earth element Y in a vacuum drying oven for baking treatment; S3. In the main crucible of the electric arc melting furnace, Si, X, Y, Al, Zr and Nb raw materials are loaded in order from bottom to top, and 70-90 g of sponge zirconium is loaded in the secondary crucible. S4. After evacuating the furnace containing the raw materials, fill it with high-purity argon as a protective atmosphere and carry out arc melting. After melting is completed, cool the furnace to obtain button ingot samples. S5. The button ingot sample is repeatedly melted 6-8 times under an argon protective atmosphere, and then cooled to obtain the Nb-Si ultra-high temperature alloy.

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