A low-density high room-temperature fracture toughness high-temperature oxidation resistant Nb-Si-Ti-Zr alloy

Abstract

This invention relates to the field of alloy materials and provides a low-density Nb-Si-Ti-Zr alloy with high room-temperature fracture toughness and high-temperature oxidation resistance. The alloy is composed of Nb, Si, Ti, and Zr, wherein the Si content is 18-19%, the Ti content is 24-26%, the Zr content is 8-10%, and the balance is Nb. This invention achieves improved room-temperature fracture toughness and high-temperature oxidation resistance while reducing density compared to existing Nb-Si-Ti alloys through alloy composition design. The provided alloy material consists of Nbss and Nb5Si3 phases, with Zr dissolved in the Nbss and Nb5Si3 phases, forming solid solution strengthening. Furthermore, the addition of Zr promotes the formation of the Nbss and Nb5Si3 phases. This allows the Nb-Si-Ti-Zr alloy to retain the high melting point and high strength advantages of existing Nb-Si-Ti materials while significantly improving its room-temperature fracture toughness and high-temperature oxidation resistance, thus meeting the requirements of the aerospace field for lightweight, high-melting-point, and oxidation-resistant high-temperature structural materials.

Description

Technical Field

[0001] This invention belongs to the field of alloys, specifically relating to a low-density Nb-Si-Ti-Zr alloy with high room temperature fracture toughness and resistance to high-temperature oxidation. Background Technology

[0002] For decades, nickel-based superalloys, possessing high toughness and strength, have been the main representatives of high-temperature structural materials development. However, with the rapid advancement of aerospace technology, the performance requirements of aero-engines are constantly increasing, leading to a continuous rise in their thrust-to-weight ratio and turbine inlet temperature. This poses even more stringent challenges to the high-temperature resistance of materials for key hot-end components. Nitrogen (Nb), as a typical refractory metal, has a density of only 8.57 g / cm³. 3 Similar to steel, its silicide-based intermetallic compound Nb5Si3 has a density of only 7.16 g / cm³. 3 This means that while achieving 85% of the weight of nickel-based alloys, it can provide superior melting point and strength. This high strength performance at similar densities makes it an ideal material for high-temperature structural applications. Therefore, Nb-Si based alloys are expected to replace Ni-based high-temperature alloys.

[0003] Due to the predominantly strong covalent bonds in refractory metal silicides, they exhibit significant brittle fracture behavior at room temperature. Furthermore, the "Pest" oxidation phenomenon in the Nbss phase of Nb-Si based alloys prevents the formation of a dense oxide layer on the alloy surface at medium to high temperatures, leading to a sharp decline in oxidation resistance. Typically, lightweight alloying elements with high oxygen affinity are added to Nb-Si based alloys to modify them. This process retains their high-temperature resistance and high strength while reducing density and improving high-temperature oxidation resistance, thus meeting the demands of modern industry for lightweight materials and superior high-temperature performance. Summary of the Invention

[0004] The purpose of this invention is to leverage the advantages of high melting point and high strength of Nb-Si based alloys, and to solve the problems of low room temperature fracture toughness and poor high temperature oxidation resistance. By adding alloying elements Ti and Zr, a low-density Nb-Si-Ti-Zr alloy material with high room temperature fracture toughness and high temperature oxidation resistance is proposed.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions.

[0006] A low-density Nb-Si-Ti-Zr alloy with high room temperature fracture toughness and resistance to high-temperature oxidation is composed of four elements: niobium (Nb), silicon (Si), titanium (Ti), and zirconium (Zr). The atomic percentage of silicon is 18-19%, that of titanium is 24-26%, that of zirconium is 8-10%, and the remainder is niobium. The alloy is composed of Nbss and Nb5Si3 phases.

[0007] Compared with the prior art, the present invention has the following advantages:

[0008] (1) The present invention designs a low-density, high-room-temperature fracture toughness and high-temperature oxidation resistant Nb-Si-Ti-Zr alloy, which is mainly obtained by adding alloying element Zr to Nb-Si-Ti alloy. The alloy is composed of Nbss and Nb5Si3 phases. Zr is mainly dissolved in Nbss and Nb5Si3 phases to form solid solution strengthening, which improves the mechanical properties of the alloy.

[0009] (2) The density of the alloy is 7.045 g / cm³. 3 ~7.078 g / cm³ 3 Between these values, the density of the existing Nb-19Si-26Ti alloy is 7.192 g / cm³. 3 In comparison, its density value is further reduced.

[0010] (3) The alloy exhibits a compressive strength of 2102 MPa during room temperature compression, which is higher than the existing Nb-19Si-26Ti alloy's 1816 MPa.

[0011] (3) The room temperature fracture toughness of the alloy during the three-point bending test at room temperature is 17.61 MPa·m. 1 / 2 This is higher than the 14.01 MPa·m of the existing Nb-19Si-26Ti alloy. 1 / 2 .

[0012] (4) The alloy exhibits good high-temperature oxidation resistance during the oxidation process at 1250 °C. Compared with the existing Nb-19Si-26Ti alloy, after oxidation at 1250 °C for 10 h, the oxidation weight gain is 49% of that of the Nb-19Si-26Ti alloy, and its high-temperature oxidation resistance has been significantly improved. Attached Figure Description

[0013] Figure 1 This is an X-ray diffraction analysis result of the Nb-19Si-26Ti alloy in Example 1.

[0014] Figure 2 This is a scanning electron backscatter photograph of the Nb-19Si-26Ti alloy in Example 1.

[0015] Figure 3 This is an X-ray diffraction analysis result of the Nb-19Si-26Ti-10Zr alloy in Example 2.

[0016] Figure 4 This is a scanning electron backscattering image of the Nb-19Si-26Ti-10Zr alloy in Example 2. Detailed Implementation

[0017] To make the content of this invention easier to understand, the invention will be explained below through specific embodiments.

[0018] Example 1

[0019] This embodiment is an Nb-19Si-26Ti alloy, composed of three elements: Nb, Si, and Ti. The relative atomic percentage content of Nb is 55%, that of Si is 19%, and that of Ti is 26%. The Nb-19Si-26Ti alloy consists of three phases: Nbss, Nb3Si, and Nb5Si3.

[0020] The purity of the Nb and Ti powder raw materials is higher than 99.9%.

[0021] The purity of Si powder raw material is higher than 99.99%.

[0022] The Nb-19Si-26Ti alloy bulk material was fabricated using a multi-stage, multi-layer laser additive manufacturing technique, specifically:

[0023] (1) According to the composition of Nb-19Si-26Ti (.at%), weigh Nb powder with a purity of 99.9% and a particle size of 15-55 μm, Si powder with a purity of 99.99% and a particle size of 50-100 μm, and Ti powder with a purity of 99.9% and a particle size of 40-80 μm for batching.

[0024] (2) Place the weighed powder into a ball mill and ball mill for 7 hours to obtain a uniformly mixed powder. The ball mill jar and grinding balls used in the ball mill are made of agate. The ball-to-powder ratio is 3:1, and the speed of the ball mill is 180 r / min. Place the mixed powder into a vacuum drying oven at 60 ℃ and dry for 2 hours.

[0025] (3) Ti-6Al-4V is used as the substrate.

[0026] (4) A fiber laser processing system was used, and the laser process parameters were set as follows: positive defocusing amount of 35 mm, spot diameter of 2.56 mm, laser power of 900 W, laser scanning speed of 5 mm / s, multi-pass overlap rate of 30%, distance from powder outlet to substrate of 15 mm, powder feeder speed of 2 rpm, protective gas flow rate of 10 L / min, and powder feeder flow rate of 15 L / min during the experiment. Each layer was printed with a rise of 1 mm, and after two consecutive depositions, the process was paused for 180 s. Argon was used as the protective gas during the preparation process. The desired product was synthesized through in-situ reaction to obtain a single-layer Nb-19Si-26Ti alloy.

[0027] (5) Using the obtained single-layer alloy as the matrix, repeat steps (3) and (4) to obtain a bulk Nb-19Si-26Ti alloy after multi-layer cladding.

[0028] X-ray diffraction analysis was performed on the prepared Nb-19Si-26Ti alloy, and the results are as follows: Figure 1 As shown, from Figure 1 It can be seen that the obtained product consists of Nbss phase, Nb3Si phase and Nb5Si3 phase.

[0029] Figure 2 The image shows a scanning electron backscattering (SPR) image of the Nb-19Si-26Ti alloy prepared according to the foregoing embodiments. Figure 2 The microstructure shown further illustrates that the obtained Nb-19Si-26Ti alloy is composed of Nbss phase, Nb3Si phase and Nb5Si3 phase, and the Ti element is mainly dissolved in Nbss and Nb3Si phase.

[0030] The density of the Nb-19Si-26Ti alloy was measured and found to be 7.192 g / cm³. 3 .

[0031] The high-temperature oxidation resistance of the Nb-19Si-26Ti alloy at 1250 ℃ was tested. After 10 h of high-temperature oxidation, the final oxidation weight gain of the alloy was 34 mg / mm². 2 .

[0032] The compressive mechanical properties of the Nb-19Si-26Ti alloy at room temperature were tested, and the compressive strength reached 1816 MPa.

[0033] Three-point bending tests were conducted on the Nb-19Si-26Ti alloy, and its room temperature fracture toughness reached 14.010 MPa·m. 1 / 2 .

[0034] Example 2

[0035] This embodiment describes an Nb-19Si-26Ti-10Zr alloy, composed of four elements: Nb, Si, Ti, and Zr. The relative atomic percentage content of Nb is 45%, that of Si is 19%, that of Ti is 26%, and that of Zr is 10%. The Nb-19Si-26Ti-10Zr alloy consists of Nbss and Nb5Si3 phases, with Zr mainly dissolved in the Nbss and Nb5Si3 phases.

[0036] The purity of the Nb and Ti powder raw materials is higher than 99.9%.

[0037] The purity of Si powder raw material is higher than 99.99%.

[0038] The purity of Zr powder raw materials is higher than 99.95%.

[0039] The Nb-19Si-26Ti-10Zr alloy was prepared using laser additive manufacturing technology, specifically:

[0040] (1) According to the composition of Nb-19Si-26Ti-10Zr(.at%), weigh Nb powder with a purity of 99.9% and a particle size of 15-55 μm, Si powder with a purity of 99.99% and a particle size of 50-100 μm, Ti powder with a purity of 99.9% and a particle size of 40-80 μm, and Zr powder with a purity of 99.95% and a particle size of 15-55 μm for batching.

[0041] (2) Place the weighed powder into a ball mill and ball mill for 7 hours to obtain a uniformly mixed powder. The ball mill jar and grinding balls used in the ball mill are made of agate. The ball-to-powder ratio is 3:1, and the speed of the ball mill is 180 r / min. Place the mixed powder into a vacuum drying oven at 60 ℃ and dry for 2 hours.

[0042] (3) Ti-6Al-4V is used as the substrate.

[0043] (4) A fiber laser processing system was used, and the laser process parameters were set as follows: positive defocusing amount of 35 mm, spot diameter of 2.56 mm, laser power of 900 W, laser scanning speed of 5 mm / s, multi-pass overlap rate of 30%, distance from powder outlet to substrate of 15 mm, powder feeder speed of 2 rpm, protective gas flow rate of 10 L / min, and powder feeder flow rate of 15 L / min during the experiment. Each layer was printed with a rise of 1 mm, and after two consecutive depositions, the process was paused for 180 s. Argon was used as the protective gas during the preparation process. The desired product was synthesized through in-situ reaction to obtain a single-layer Nb-19Si-26Ti-10Zr alloy.

[0044] (5) Using the obtained single-layer alloy as the substrate, repeat steps (3) and (4) to obtain a bulk Nb-19Si-26Ti-10Zr alloy after multi-layer cladding.

[0045] The density of the Nb-19Si-26Ti-10Zr alloy was measured and found to be 7.045 g / cm³. 3 The density of the existing Nb-19Si-26Ti alloy is 7.192 g / cm³. 3 Compared to that, it decreased by 2.04%.

[0046] The high-temperature oxidation resistance of the Nb-19Si-26Ti-10Zr alloy at 1250 ℃ was tested. After 10 h of high-temperature oxidation, the final oxidation weight gain of the alloy was 16.67 mg / mm². 2 It is 49% of the existing Nb-19Si-26Ti alloy, and its oxidation resistance has been significantly improved.

[0047] Room temperature compressive mechanical properties of Nb-19Si-26Ti-10Zr were tested, and the results showed that its compressive strength could reach 2102 MPa, which is 115% of that of existing Nb-19Si-26Ti alloys.

[0048] Three-point bending tests were conducted on Nb-19Si-26Ti-10Zr, and the results showed that its room temperature fracture toughness reached 17.61 MPa·m. 1 / 2 It is 125% of the existing Nb-19Si-26Ti alloy.

[0049] The above is a description of preferred embodiments of the present invention. It should be noted that the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, or improvements made to the present invention, provided they satisfy the scope of the claims, the content of the invention, and the accompanying drawings, should be included within the protection scope of the present invention.

Claims

1. A low-density Nb-Si-Ti-Zr alloy with high room-temperature fracture toughness and resistance to high-temperature oxidation, characterized in that: It is composed of four elements: niobium, silicon, titanium, and zirconium. The atomic percentage of silicon is 18-19%, that of titanium is 24-26%, that of zirconium is 8-10%, and the remainder is niobium.

2. The low-density, high-room-temperature fracture toughness, and high-temperature oxidation-resistant Nb-Si-Ti-Zr alloy as described in claim 1, characterized in that: When preparing the high room temperature fracture toughness and high temperature oxidation resistance alloy, the purity of the Nb, Si, Ti and Zr raw materials used shall not be less than 99.9%.

3. The low-density, high-room-temperature fracture toughness, and high-temperature oxidation-resistant Nb-Si-Ti-Zr alloy as described in claim 1, characterized in that: The selected Nb powder has a particle size of 15–55 μm, Si powder has a particle size of 50–100 μm, Ti has a particle size of 40–80 μm, and Zr powder has a particle size of 15–55 μm.

4. The low-density, high-room-temperature fracture toughness, and high-temperature oxidation-resistant Nb-Si-Ti-Zr alloy as described in claim 1, characterized in that: It is an Nb-19Si-26Ti-10Zr alloy, composed of four elements: Nb, Si, Ti, and Zr. The relative atomic percentage content of Nb is 45%, that of Si is 19%, that of Ti is 26%, and that of Zr is 10%.

5. The low-density, high-room-temperature fracture toughness, and high-temperature oxidation-resistant Nb-Si-Ti-Zr alloy as described in claim 1, characterized in that: The Nb-19Si-26Ti-10Zr alloy is composed of Nbss and Nb5Si3 phases, with Zr mainly dissolved in the Nbss and Nb5Si3 phases.

6. A method for preparing a low-density Nb-Si-Ti-Zr alloy with high room temperature fracture toughness and resistance to high-temperature oxidation as described in any one of claims 1-5, characterized in that, Prepared by the following steps: (1) Weigh Nb, Si, Ti and Zr powders according to the proportion and mix them by ball milling at room temperature. Before ball milling, fill the ball milling jar with argon gas and seal it. After ball milling, transfer the mixed powder to a vacuum drying oven and dry it at 60 °C for 2 hours. (2) The dried mixed powder was subjected to multi-pass, multi-layer laser additive manufacturing on a Ti-6Al-4V substrate using a laser processing system to finally obtain an Nb-Si-Ti-Zr alloy bulk.

7. The method for preparing the low-density, high-room-temperature fracture toughness, and high-temperature oxidation-resistant Nb-Si-Ti-Zr alloy as described in claim 6, characterized in that, When mixing powders in a ball mill, the ball-to-powder ratio is 3:1, the ball mill speed is 180 r / min, and the ball milling time is 7 h.

8. The method for preparing the low-density, high-room-temperature fracture toughness, and high-temperature oxidation-resistant Nb-Si-Ti-Zr alloy as described in claim 6, characterized in that, The laser process parameters were as follows: positive defocusing amount of 35 mm, spot diameter of 2.56 mm, laser power of 900 W, laser scanning speed of 5 mm / s, multi-pass overlap rate of 30%, distance from powder outlet to substrate of 15 mm, powder feeder speed of 2 rpm, protective gas flow rate of 10 L / min and powder feeder flow rate of 15 L / min during the experiment; each printed layer rose 1 mm, and after two consecutive depositions, the process was paused for 180 s. Argon was used as the protective gas during the preparation process.

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