A high-temperature alloy with high toughness and a method for preparing the same

Abstract

The application relates to a high-temperature alloy with higher toughness and a preparation method thereof, and aims to solve the problems of large raw material loss, poor or unstable room-temperature toughness of Nb-Si-based ultrahigh-temperature alloy, and the high-temperature alloy with higher toughness is composed of 16% of Si, 20% of Zr, 0.05-0.4% of m and the balance of Nb in terms of atomic percentage, wherein the m element is Cr, C, Hf, Ta or Sc, and the alloy is prepared by vacuum arc furnace smelting, when Zr element is used to replace Ti element, the alloy is composed of Nbss phase and gamma(Nb,X)5Si3 phase, so that the alloy can be toughened. Cr, C, Hf, Ta or Sc are added to produce the solid solution strengthening effect. The application is applied to the alloy preparation field.

Description

Technical Field

[0001] This invention relates to a high-temperature alloy with high toughness and its preparation method. Background Technology

[0002] With the continuous development of aerospace technology, the requirements for engines are becoming increasingly stringent, demanding higher thrust-to-weight ratios and higher operating temperatures. Currently, the operating temperature of third-generation Ni-based single-crystal superalloys for domestic aero-engine blades has reached 1150℃, reaching 85% of their melting point. Therefore, the development of a new generation of high-temperature materials is necessary. Nb-Si-based superalloys consist of an Nbss phase with excellent plasticity and toughness and a silicide phase with high high-temperature strength and creep resistance. They possess low density and a high melting point, and are expected to become an important research target for next-generation engine materials. However, their widespread application is currently hindered by their extremely poor room-temperature fracture toughness, which cannot meet the requirements for room-temperature processing and assembly. Therefore, toughening treatment of Nb-Si alloys remains a problem to be solved.

[0003] Currently, the Nb-Si high-temperature alloy system is mainly based on Nb-Si-Ti. However, Ti is chemically very reactive and easily forms the Tiss phase. Once the Tiss phase precipitates, it will affect the mechanical properties of the alloy. Moreover, the high reactivity of Ti leads to significant losses, which in turn increases the cost of smelting. Therefore, there is an urgent need for an Nb-Si alloy system with less raw material loss, higher room temperature toughness, and greater stability. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of high raw material loss, poor room temperature toughness, or instability in Nb-Si based ultra-high temperature alloys, and to propose a high-temperature alloy with high toughness and its preparation method.

[0005] The present invention discloses a high-temperature alloy with high toughness, which is composed of 16% Si, 20% Zr, 0.05-0.4% m and the balance Nb by atomic percentage; wherein the m element is Cr, C, Hf, Ta or Sc.

[0006] The present invention discloses a method for preparing a high-temperature alloy with high toughness, which is carried out according to the following steps:

[0007] 1. Weigh the raw materials according to the stated atomic ratio;

[0008] 2. The raw materials are pretreated and then added to the crucible of the melting furnace. Sponge titanium is then added to another crucible in the melting furnace. The melting furnace is then evacuated and filled with argon gas for protective melting. After cooling, the sample is obtained.

[0009] 3. The sample is repeatedly melted 6-8 times and cooled to obtain a high-toughness Nb-Si based alloy.

[0010] The present invention has the following beneficial effects:

[0011] 1. When Zr is used to replace Ti, the enrichment of Ti to form a titanium-based solid solution phase is avoided, which would lead to segregation in the alloy and negatively affect the mechanical properties of the alloy.

[0012] Second, when Zr is used to replace Ti, the alloy consists of Nbss phase and γ(Nb,X)5Si3 phase, and the γ(Nb,X)5Si3 phase has the highest toughness among the three types of (Nb,X)5Si3 phases. Therefore, it can play a role in toughening the alloy.

[0013] Third, the addition of five commonly used alloying elements (Cr, C, Hf, Ta, and Sc) to Nb-Si-Zr based alloys produces solid solution strengthening, further improving the mechanical properties of the alloys. The Nbss phase belongs to the BCC structure, with a space utilization rate of only 68%. Furthermore, Nb is chemically inert, so multiple elements exhibit good solid solution effects in this phase. Cr and Sc are small and large atomic radius substitution elements, respectively. Cr and Sc atoms undergo substitutional solid solution in the Nbss phase, resulting in significant lattice distortion. When dislocations move to the vicinity of the lattice distortion, they require more energy to advance, thus enhancing the alloy's strength and toughness. Ta and Nb are in the same group, as are Zr. It is predicted that Ta will dissolve significantly into the Nbss phase or silicide phase formed by Nb and Zr, producing solid solution strengthening and improving the alloy's mechanical properties. C element dissolves in the phase via interstitial solid solution, which alters the crystal structure and hinders the movement of defects such as dislocations.

[0014] IV. The high-temperature material prepared by the method of the present invention can have its performance further improved after heat treatment or directional solidification, making it a highly promising high-temperature alloy structural material. Attached Figure Description

[0015] Figure 1 The image shows the microstructure of the Nb-16Si-20Zr-4Cr alloy prepared in Example 1.

[0016] Figure 2 The microstructure of the Nb-16Si-20Zr-2C alloy prepared in Example 2 is shown in the image.

[0017] Figure 3 The image shows the microstructure of the Nb-16Si-20Zr-4Hf alloy prepared in Example 3.

[0018] Figure 4The microstructure of the Nb-16Si-20Zr-4Ta alloy prepared in Example 4 is shown in the image.

[0019] Figure 5 The image shows the microstructure of the Nb-16Si-20Zr-0.5Sc-based alloy prepared in Example 5.

[0020] Figure 6 The room temperature fracture toughness of the Nb-Si-Zr based alloys prepared in Examples 1 to 5;

[0021] Figure 7 The figures show the percentage packing of phases in the Nb-Si-Zr based alloy microstructures prepared in Examples 1 to 5. Detailed Implementation

[0022] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0023] Specific implementation method one: In this implementation method, a high-temperature alloy with high toughness is composed of 16% Si, 20% Zr, 0.05-0.4% m and the balance Nb by atomic percentage; wherein the m element is Cr, C, Hf, Ta or Sc.

[0024] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the alloy consists of 60% Nb, 16% Si, 20% Zr, and 4% Cr by atomic percentage, expressed as Nb-16Si-20Zr-4Cr. Everything else is the same as in Specific Implementation Method One.

[0025] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the alloy is composed of 62% Nb, 16% Si, 20% Zr, and 2% C by atomic percentage, expressed as Nb-16Si-20Zr-2C. Everything else is the same as in Specific Implementation Method One or Two.

[0026] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the alloy is composed of 60% Nb, 16% Si, 20% Zr, and 4% Hf by atomic percentage, expressed as Nb-16Si-20Zr-4Hf. Everything else is the same as in Specific Implementation Methods One to Three.

[0027] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the alloy is composed of 60% Nb, 16% Si, 20% Zr, and 4% Ta by atomic percentage, expressed as Nb-16Si-20Zr-4Ta. Everything else is the same as in Specific Implementation Methods One to Four.

[0028] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the alloy is composed of 63.5% Nb, 16% Si, 20% Zr, and 0.5% Sc by atomic percentage, expressed as Nb-16Si-20Zr-0.5Sc. Everything else is the same as in Specific Implementation Methods One to Five.

[0029] Specific Implementation Method Seven: This implementation method describes a method for preparing a high-temperature alloy with high toughness, which is carried out according to the following steps:

[0030] 1. Weigh the raw materials according to the stated atomic ratio;

[0031] 2. The raw materials are pretreated and then added to the crucible of the melting furnace. Sponge titanium is then added to another crucible in the melting furnace. The melting furnace is then evacuated and filled with argon gas for protective melting. After cooling, the sample is obtained.

[0032] 3. The sample is repeatedly melted 6-8 times and cooled to obtain a high-toughness Nb-Si based alloy.

[0033] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the pretreatment steps in step two consist of removing oxide scale, two ultrasonic cleanings, and drying. The first ultrasonic cleaning lasts 5-20 minutes, with a power of 60W-150W and a frequency of 15kHz-35kHz, using acetone as the cleaning solution. The second cleaning lasts 3-8 minutes, with a power of 90W-140W and a frequency of 20kHz-30kHz, using anhydrous ethanol as the cleaning solution. Everything else is the same as in Specific Implementation Method Seven.

[0034] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods Seven or Eight in that: in step two, the vacuum is evacuated to 1×10⁻⁶. -3 Pa ~ 5 × 10 -3 Pa, argon gas is introduced to a pressure of 0.02MPa-0.6MPa. Other aspects are the same as in specific embodiments seven or eight.

[0035] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods Seven to Nine in that: in step two, a non-consumable vacuum arc melting furnace is used for vacuum melting. The current of the arc melting furnace is 100A-600A. During alloy melting and cooling, the current decreases by 50A every 10 seconds, and the flow rate of the circulating cooling water is 1m / s-5m / s. Everything else is the same as in Specific Implementation Methods Seven to Nine.

[0036] The beneficial effects of the present invention are verified using the following embodiments:

[0037] Example 1: A high-temperature alloy with high toughness, composed of the following components: 60 at.% Nb, 16 at.% Si, 20 at.% Zr, and 4 at.% Cr.

[0038] Its preparation method is as follows:

[0039] (1) Weigh the raw materials Nb, Si, Zr, and Cr according to the above atomic ratio, wherein Nb is 99.95% pure. ×2mm particles, wherein Si is 1-3mm irregular particles with a purity of 99.95%, Zr is 1-3mm irregular particles with a purity of 99.95%, Cr is dendritic particles with a purity of 99.5%, and an additional 80-100g of sponge titanium is weighed out for oxygen absorption.

[0040] (2) The raw materials and sponge titanium were pretreated to remove the oxide scale and impurities on the surface. The surface was polished with 400# SiC water sandpaper. Then the raw materials were placed in acetone solution for the first ultrasonic cleaning, which lasted for 15 minutes, with a power of 125W and a frequency of 30kHz. Then anhydrous ethanol was used for the second ultrasonic cleaning for 5 minutes, with a power of 120W and a frequency of 30kHz.

[0041] (3) The pretreated raw materials are placed sequentially from bottom to top in the crucibles of the non-consumable vacuum melting electric arc furnace chamber in the order of Si, Zr, Cr, and Nb. The pretreated sponge titanium is then placed in the adjacent crucibles. During melting, the furnace chamber is first evacuated to a vacuum level of 3 × 10⁻⁶. -3 Pa, then high-purity argon gas was injected into the furnace, causing the pressure gauge on the furnace to reach -0.05 MPa. The melting current was slowly increased from 0 A to 600 A, and the flow rate of the circulating cooling water was 3 m / s. First, the sponge titanium was melted to absorb the residual oxygen in the furnace cavity and prevent oxidation. Then, the raw materials were melted. When the current reached 600 A, it was held for 30 seconds. After cooling, Nb-16Si-20Zr-4Cr button ingots were obtained.

[0042] (4) To ensure uniform alloy composition, the button ingot was rotated 180° using the furnace's built-in robotic arm, and the melting process was repeated 8 times. During the cooling stage of the last melting, the cooling rate was controlled by adjusting the rate of current reduction. The current reduction rate was 50A per 10s, and the Nb-16Si-20Zr-4Cr alloy was finally obtained.

[0043] Example 2: A high-temperature alloy with high toughness, composed of the following components: 62 at.% Nb, 16 at.% Si, 20 at.% Zr, and 2 at.% C.

[0044] Its preparation method is as follows:

[0045] (1) Weigh the raw materials Nb, Si, Zr, and C elements according to the above atomic ratio, wherein Nb has a purity of 99.95%. ×2mm particles, wherein Si is 1-3mm irregular particles with 99.95% purity, Zr is 1-3mm irregular particles with 99.95% purity, and C is carbon powder with a particle size of 5μm. After weighing, the particles are wrapped in aluminum foil, and an additional 80-100g of sponge titanium is weighed for oxygen absorption.

[0046] (2) The raw materials (excluding C powder) and the oxygen-absorbing sponge titanium were pretreated to remove the oxide scale and impurities. The surface was then polished with 400# SiC wet sandpaper. The raw materials were then placed in an acetone solution for the first ultrasonic cleaning, which lasted 15 minutes at a power of 125W and a frequency of 30kHz. After the first ultrasonic cleaning, the raw materials were subjected to a second ultrasonic cleaning with anhydrous ethanol for 5 minutes at a power of 120W and a frequency of 30kHz.

[0047] (3) The raw materials are added to the crucible of the vacuum melting furnace in the following order: C (wrapped in aluminum foil), Si, Zr, and Nb, from bottom to top. The carbon powder wrapped in aluminum foil is placed at the bottom of the crucible to prevent the volatilization of C powder during melting from affecting the composition of the button ingot. Sponge titanium is placed in an adjacent crucible. During melting, the furnace cavity is first evacuated to a vacuum level of 3 × 10⁻⁶. -3 Pa, then high-purity argon gas was injected into the furnace, causing the pressure gauge on the furnace to reach -0.05 MPa. The melting current was slowly increased from 0 A to 600 A, and the flow rate of the circulating cooling water was 3 m / s. First, the sponge titanium was melted to absorb residual oxygen in the furnace chamber and prevent oxidation. Then, the raw materials were melted. When the current reached 600 A, it was held for 30 seconds. After cooling, Nb-16Si-20Zr-2C button ingots were obtained.

[0048] (4) To ensure uniform alloy composition, the button ingot was rotated 180° using a robotic arm attached to the furnace, and the melting process was repeated 8 times. During the cooling stage of the last melting, the cooling rate was controlled by adjusting the rate of current reduction. The current reduction rate was 50A per 10s, ultimately yielding an Nb-16Si-20Zr-2C alloy with high fracture toughness.

[0049] Example 3: A high-temperature alloy with high toughness, composed of the following components: 60 at.% Nb, 16 at.% Si, 20 at.% Zr, and 4 at.% Hf.

[0050] Its preparation method is as follows:

[0051] (1) Weigh the raw materials Nb, Si, Zr, and Hf according to the above atomic ratio, wherein Nb has a purity of 99.95%. ×2mm particles, wherein Si is 1-3mm irregular particles with 99.95% purity, Zr is 1-3mm irregular particles with 99.95% purity, and Hf is dendritic particles with 99.95% purity; an additional 80-100g of sponge titanium is weighed for oxygen absorption.

[0052] (2) The raw materials and the titanium sponge used for oxygen absorption were pretreated to remove the oxide scale and impurities. The surface was then polished with 400# SiC wet sandpaper. The raw materials were then placed in an acetone solution for the first ultrasonic cleaning, which lasted 15 minutes at a power of 125W and a frequency of 30kHz. After the first ultrasonic cleaning, the materials were subjected to a second ultrasonic cleaning with anhydrous ethanol for 5 minutes at a power of 120W and a frequency of 30kHz.

[0053] (3) The pretreated raw materials are added to the crucible of the vacuum melting furnace in the order of Si, Zr, Nb, and Hf from bottom to top. The pretreated sponge titanium is then placed in adjacent crucibles. During melting, the furnace cavity is first evacuated to a vacuum level of 3 × 10⁻⁶. -3 Pa, then high-purity argon gas was injected into the furnace, causing the pressure gauge on the furnace to reach -0.05 MPa. The melting current was slowly increased from 0 A to 600 A, and the flow rate of the circulating cooling water was 3 m / s. First, the sponge titanium was melted to absorb residual oxygen in the furnace chamber and prevent oxidation. Then, the raw materials were melted. When the current reached 600 A, it was held for 30 seconds. After cooling, Nb-16Si-20Zr-4Hf button ingots were obtained.

[0054] (4) To ensure uniform alloy composition, the button ingot was rotated 180° using a robotic arm attached to the furnace, and the melting process was repeated 8 times. During the cooling stage of the last melting, the cooling rate was controlled by adjusting the rate of current reduction. The current reduction rate was 50A per 10s, ultimately yielding an Nb-16Si-20Zr-4Hf alloy with high fracture toughness.

[0055] Example 4: A high-temperature alloy with high toughness, composed of the following components: 60 at.% Nb, 16 at.% Si, 20 at.% Zr, and 4 at.% Ta.

[0056] Its preparation method is as follows:

[0057] (1) Weigh the raw materials Nb, Si, Zr, and Ta according to the above atomic ratio, wherein Nb has a purity of 99.95%. ×2mm particles, wherein Si is 1-3mm irregular particles with 99.95% purity, Zr is 1-3mm irregular particles with 99.95% purity, Ta is irregular particles with 99.95% purity, and an additional 80-100g of sponge titanium is weighed for oxygen absorption.

[0058] (2) The raw materials and sponge titanium were pretreated to remove the oxide scale and impurities. The surface was then polished with 400# SiC wet sandpaper. The raw materials were then placed in an acetone solution for the first ultrasonic cleaning, which lasted 15 minutes at a power of 125W and a frequency of 30kHz. After the first ultrasonic cleaning, the material was subjected to a second ultrasonic cleaning with anhydrous ethanol for 5 minutes at a power of 120W and a frequency of 30kHz.

[0059] (3) The pretreated raw materials are added to the crucible of the vacuum melting furnace in the order of Si, Zr, Nb, and Ta from bottom to top. The pretreated sponge titanium is then placed in an adjacent crucible. During melting, the furnace cavity is first evacuated to a vacuum level of 3 × 10⁻⁶. -3 Pa, then high-purity argon gas was injected into the furnace, causing the pressure gauge on the furnace to reach -0.05 MPa. The melting current was slowly increased from 0 A to 600 A, and the flow rate of the circulating cooling water was 3 m / s. First, the sponge titanium was melted to absorb residual oxygen in the furnace chamber and prevent oxidation. Then, the raw materials were melted. When the current reached 600 A, it was held for 30 seconds. After cooling, Nb-16Si-20Zr-4Hf button ingots were obtained.

[0060] (4) To ensure uniform alloy composition, the button ingot was rotated 180° using a robotic arm attached to the furnace, and the melting process was repeated 8 times. During the cooling stage of the last melting, the cooling rate was controlled by adjusting the rate of current reduction. The current reduction rate was 50A per 10s, ultimately yielding an Nb-16Si-20Zr-4Ta alloy with high fracture toughness.

[0061] Example 5: A high-temperature alloy with high toughness, composed of the following components: 63.5 at.% Nb, 16 at.% Si, 20 at.% Zr, and 0.5 at.% Sc.

[0062] Its preparation method is as follows:

[0063] (1) Weigh the raw materials Nb, Si, Zr, and Sc according to the above atomic ratio, wherein Nb has a purity of 99.95%. ×2mm particles, wherein Si is 1-3mm irregular particles with a purity of 99.95%, Zr is 1-3mm irregular particles with a purity of 99.95%, Sc is scandium wire with a purity of 99.9% (vacuum-sealed), and an additional 80-100g of sponge titanium is weighed for oxygen absorption.

[0064] (2) The raw materials (excluding scandium wire, as scandium is easily oxidized, so vacuum tube sealing is used, and no surface pretreatment is required) and the oxygen-absorbing sponge titanium were pretreated to remove the oxide scale and impurities on the surface. The surface was then polished with 400# SiC wet sandpaper. The raw materials were then placed in an acetone solution for the first ultrasonic cleaning, which lasted 15 minutes at a power of 125W and a frequency of 30kHz. After the first ultrasonic cleaning, the materials were subjected to a second ultrasonic cleaning with anhydrous ethanol for 5 minutes at a power of 120W and a frequency of 30kHz.

[0065] (3) The pretreated raw materials are added to the crucible of the vacuum melting furnace in the order of Si, Sc, Zr, and Nb from bottom to top. The pretreated sponge titanium is then placed in an adjacent crucible. During melting, the furnace cavity is first evacuated to a vacuum level of 3 × 10⁻⁶. -3 Pa, then high-purity argon gas was injected into the furnace, causing the pressure gauge on the furnace to reach -0.05 MPa. The melting current was slowly increased from 0 A to 600 A, and the flow rate of the circulating cooling water was 3 m / s. First, the sponge titanium was melted to absorb residual oxygen in the furnace chamber and prevent oxidation. Then, the raw materials were melted. When the current reached 600 A, it was held for 30 seconds. After cooling, Nb-16Si-20Zr-4Hf button ingots were obtained.

[0066] (4) To ensure uniform alloy composition, the button ingot was rotated 180° using a robotic arm attached to the furnace, and the melting process was repeated 8 times. During the cooling stage of the last melting, the cooling rate was controlled by adjusting the rate of current reduction. The current reduction rate was 50A per 10s, ultimately yielding an Nb-16Si-20Zr-0.5Sc alloy with high fracture toughness.

[0067] Microstructure images of the Nb-Si-Zr based alloys prepared in Examples 1 to 5 are shown below. Figure 1-5As shown, the microstructures of the five alloys prepared in Examples 1 to 5 all possess Nbss phase (light gray phase) and γ(Nb,X)5Si3 phase (gray phase), where X is the alloying element replacing Nb. Due to the effect of Zr, the silicide phase is γ(Nb,X)5Si3, and the γ(Nb,X)5Si3 phase exhibits the highest toughness among the three types of (Nb,X)5Si3 phases. Therefore, the Nb-Si-Zr based superalloys possess high room temperature fracture toughness. Among them, the Nb-16Si-20Zr-4Cr, Nb-16Si-20Zr-4Ta, and Nb-16Si-20Zr-0.5Sc alloys prepared in Examples 1, 4, and 5 have a dark gray, Zr-rich γ(Nb,X)5Si3 phase in their microstructure, with significant segregation. Its microstructure consists of a large primary Nbss phase and an Nbss / γ(Nb,X)5Si3 eutectoid structure, which is unevenly distributed. The Nb-16Si-20Zr-4Hf alloy prepared in Example 3 has no Zr-rich phase in its microstructure, exhibits less microsegregation, and its microstructure consists of a large primary Nbss phase and an Nbss / γ(Nb,X)5Si3 eutectoid structure, resulting in better performance. The Nb-16Si-20Zr-2C alloy prepared in Example 2 consists of a large amount of Nbss / γ(Nb,X)5Si3 eutectoid structure and a primary Nbss phase, with a small phase size. It lacks a Zr-rich phase and exhibits less microsegregation. The Nbss phase is coupled with the γ(Nb,X)5Si3 phase, resulting in a relatively uniform microstructure distribution, fine phase size, and excellent performance.

[0068] The room temperature fracture toughness of the Nb-Si-Zr based alloys prepared in Examples 1 to 5 is as follows: Figure 6 As shown, the room temperature fracture toughness of the Nb-16Si-20Zr-4Cr alloy prepared in Example 1 is 8.28 MPa·m. 1 / 2 After composition optimization, the toughness of the Nb-Si-Zr based alloys prepared in Examples 2 to 5 was significantly improved. Among them, the Nb-16Si-20Zr-0.5Sc alloy prepared in Example 5 achieved a room temperature fracture toughness of 9.02 MPa·m. 1 / 2 The Nb-16Si-20Zr-4Ta alloy prepared in Example 4 exhibits a room-temperature fracture toughness of 10.67 MPa·m. 1 / 2 The Nb-16Si-20Zr-4Hf alloy prepared in Example 3 exhibits a room-temperature fracture toughness of 11.52 MPa·m. 1 / 2 The Nb-16Si-20Zr-2C alloy prepared in Example 2 exhibits a room-temperature fracture toughness of 14.45 MPa·m. 1 / 2 It has the best performance.

[0069] The packing histograms of phase percentages in the microstructures of Nb-Si-Zr-based alloys prepared in Examples 1 to 5 are shown below. Figure 7 As shown, the Nb-16Si-20Zr-4Cr alloy prepared in Example 1 has an Nbss phase ratio of 54% and a γ(Nb,X)5Si3 phase ratio of 46%. The Nb-16Si-20Zr-0.5Sc alloy prepared in Example 5 has an Nbss phase ratio of 53% and a γ(Nb,X)5Si3 phase ratio of 47%. The Nb-16Si-20Zr-4Ta alloy prepared in Example 4 has an Nbss phase ratio of 59% and a γ(Nb,X)5Si3 phase ratio of 41%. The Nb-16Si-20Zr-4Ta alloy prepared in Example 3 has an Nbss phase ratio of 60% and a γ(Nb,X)5Si3 phase ratio of 40%. The Nb-16Si-20Zr-2C alloy prepared in Example 2 has an Nbss phase ratio of 65% and a γ(Nb,X)5Si3 phase ratio of 35%. The atomic radius of Nb is 1.43 Å, Ta is 1.26 Å, Hf is 1.59 Å, Sc is 1.84 Å, Cr is 1.28 Å, and C is 0.8 Å. As a small atomic radius element, C exhibits interstitial solid solution in Nbss and γ(Nb,X)5Si3. Energy dispersive spectroscopy (EDS) analysis shows that C primarily dissolves in the Nbss phase, thus playing a stabilizing role. Therefore, the Nbss phase is the most abundant phase in the Nb-16Si-20Zr-2C alloy. The atomic radii of Hf and Ta are closer to those of Nb than those of other elements. Therefore, compared to γ(Nb,X)5Si3, they are more readily dissolved in the Nbss phase, which contains more Nb atoms, thus stabilizing the Nbss phase and resulting in a higher Nbss phase content. Conversely, Sc and Cr have a larger atomic radius than Nb, and may be more readily dissolved in the γ(Nb,X)5Si3 phase, which contains less Nb, resulting in a relatively smaller Nbss phase. Since the Nbss phase is a ductile phase while the γ(Nb,X)5Si3 phase is a hard and brittle phase, and both have a more uniform microstructure, smaller phase size, and less segregation, the Nb-16Si-20Zr-2C alloy exhibits excellent room-temperature fracture toughness.

Claims

1. A high-temperature alloy with high toughness, characterized in that, The alloy is expressed as Nb-16Si-20Zr-4Cr, Nb-16Si-20Zr-2C, Nb-16Si-20Zr-4Hf, Nb-16Si-20Zr-4Ta, or Nb-16Si-20Zr-0.5Sc; wherein Nb-16Si-20Zr-4Cr is composed of 60% Nb, 16% Si, 20% Zr, and 4% Cr by atomic percentage; and Nb-16Si-20Zr-2C is composed of 62% Nb, 16% Si, 20% Zr, and 4% Cr by atomic percentage. The Nb-16Si-20Zr-4Hf composition consists of 60%Nb, 16%Si, 20%Zr, and 4%Hf by atomic percentage; the Nb-16Si-20Zr-4Ta composition consists of 60%Nb, 16%Si, 20%Zr, and 4%Ta by atomic percentage; and the Nb-16Si-20Zr-0.5Sc composition consists of 63.5%Nb, 16%Si, 20%Zr, and 0.5%Sc by atomic percentage. The high-temperature alloy with high toughness has Nbss phase and γ(Nb,X)5Si3 phase.

2. The method for preparing a high-temperature alloy with high toughness as described in claim 1, characterized in that, The preparation method is carried out according to the following steps:

1. Weigh the raw materials according to the stated atomic ratio; 2. The raw materials are pretreated and then added to the crucible of the melting furnace. Sponge titanium is then added to another crucible in the melting furnace. The melting furnace is then evacuated and filled with argon gas for protective melting. After cooling, the sample is obtained.

3. The sample is repeatedly melted 6-8 times and cooled to obtain a high-toughness Nb-Si based alloy.

3. The method for preparing a high-temperature alloy with high toughness according to claim 2, characterized in that, Step two pretreatment steps include removing oxide scale, two ultrasonic cleanings, and drying. The first ultrasonic cleaning takes 5 to 20 minutes, with a power of 60 to 150 W and a frequency of 15 to 35 kHz, and uses acetone as the cleaning solution. The second cleaning takes 3 to 8 minutes, with a power of 90 to 140 W and a frequency of 20 to 30 kHz, and uses anhydrous ethanol as the cleaning solution.

4. The method for preparing a high-temperature alloy with high toughness according to claim 2, characterized in that, In step two, the vacuum is evacuated to 1×10⁻⁶. -3 Pa~5×10 -3 Pa, fill with argon gas to 0.02MPa-0.6MPa.

5. The method for preparing a high-temperature alloy with high toughness according to claim 2, characterized in that, In step two, a non-consumable vacuum arc melting furnace is used for vacuum melting. The current of the arc melting furnace is 100A-600A. When the alloy is melting and cooling, the current decreases by 50A every 10s. The flow rate of the circulating cooling water is 1m / s-5m / s.

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