Fifth-generation nickel-based single-crystal high-temperature alloy with high-stability structure

Abstract

The invention discloses a fifth-generation nickel-based single-crystal high-temperature alloy with a high-stability structure, which comprises the following components in percentage by mass: 2.5 to 4.5 weight percent of chromium, 6 to 10 weight percent of cobalt, 3 to 5 weight percent of tungsten, 1 to 3 weight percent of molybdenum, 5 to 6.5 weight percent of rhenium, 5 to 7 weight percent of aluminum, 7 to 10 weight percent of tantalum, 0 to 0.2 weight percent of hafnium, 3.6 to 5 weight percent of ruthenium, 0 to 0.05 weight percent of carbon, 0 to 0.03 weight percent of yttrium and the balance of nickel. The total mass fraction of rhenium, tungsten and molybdenum in the alloy is rhenium + tungsten + molybdenum less than or equal to 13.5%, and the mass fraction proportional relation of tungsten and molybdenum is tungsten / molybdenum gt; 2.2, the mass fraction proportion relation of tantalum and aluminum is that tantalum / aluminum is greater than or equal to 1.1. The invention further discloses a heat treatment process of the fifth-generation nickel-based single-crystal high-temperature alloy with the high-stability structure. The nickel-based single-crystal high-temperature alloy with high temperature bearing capacity is developed on the basis of high-temperature stability of a structure by synergistic stability elements and strong promotion of TCP phase precipitation element content, the temperature bearing capacity reaches the level of a typical fifth-generation single-crystal high-temperature alloy, and the endurance life is larger than or equal to 1000 h at the temperature of 1100 DEG C / 137 MPa.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature alloy materials, and in particular relates to a fifth-generation nickel-based single-crystal high-temperature alloy with a highly stable structure, which is suitable for turbine blades of advanced aircraft engines and gas turbines. Background Art

[0002] Among the development goals of modern aircraft engines, improving engine thrust and thrust-to-weight ratio is crucial, and the most effective way to achieve these goals is to increase the turbine inlet temperature. Therefore, the temperature bearing capacity and high-temperature mechanical properties of turbine blades need to meet higher requirements. Nickel-based single crystal high-temperature alloys have excellent high-temperature mechanical properties, oxidation resistance and corrosion resistance, and can be used as an important preparation material for modern aircraft engines and turbine blades.

[0003] In the 1980s, the first generation of nickel-based single crystal superalloys with a temperature bearing capacity of about 1010°C appeared. In the process of the development of single crystal superalloys, in order to improve their temperature bearing capacity, the content of refractory elements (such as rhenium, tungsten, molybdenum, tantalum, etc.) in the alloy gradually increased. Taking the CMSX series alloys as an example, the content of refractory elements (rhenium + tungsten + molybdenum + tantalum) in the typical first generation (CMSX-2), second generation (CMSX-4), and third generation (CMSX-10) single crystal superalloys continued to increase from about 14wt.% to more than 20wt.%. The continuous addition of refractory elements has caused the stability of the alloy structure to decrease, and harmful phases such as topologically close packed phase (TCP phase) are easily precipitated during long-term service or thermal exposure. In order to solve the problem of microstructural instability in single crystal superalloys, ruthenium is added to the fourth generation and higher generation nickel-based single crystal superalloys to inhibit the precipitation of TCP phase and improve the stability of the alloy structure; but the price of ruthenium is very expensive (more than 130,000 yuan / kg), which further increases the cost of the alloy. The fourth generation nickel-based single crystal alloy reported at home and abroad has a life span of ≥400h at 1100℃ / 137MPa, and its temperature bearing capacity has reached about 1080℃. In order to meet the increasing turbine inlet temperature, it is necessary to further improve the temperature bearing capacity and the life span of the single crystal alloy at 1100℃ / 137MPa, solve the problem of alloy structure stability and strengthening in long-term high temperature environment, so as to ensure the long life span and high temperature bearing capacity of the alloy. At the same time, in the process of alloy design, factors such as alloy cost, oxidation resistance and corrosion resistance need to be comprehensively considered. Summary of the invention

[0004] The purpose of the present invention is to propose a fifth-generation nickel-based single crystal high-temperature alloy with high structural stability and its heat treatment process in response to the needs of high-pressure turbine blades of aircraft engines with high turbine front intake temperatures. To achieve the above purpose, the technical solution adopted by the present invention is:

[0005] A fifth generation nickel-based single crystal high temperature alloy with a highly stable structure, characterized in that, in terms of mass percentage, the chemical composition of the alloy includes: 2.5wt.% to 4.5wt.% of chromium, 6wt.% to 10wt.% of cobalt, 3wt.% to 5wt.% of tungsten, 1wt.% to 2.8wt.% of molybdenum, 5wt.% to 6.5wt.% of rhenium, 5wt.% to 7wt.% of aluminum, 7wt.% to 10wt.% of tantalum, 0wt.% to 0.2wt.% of hafnium, 3.6wt.% to 5wt.% of ruthenium, 0wt.% to 0.05wt.% of carbon, 0wt.% to 0.03wt.% of yttrium, and the balance is nickel; and the total mass fraction of rhenium, tungsten and molybdenum in the alloy is rhenium + tungsten + molybdenum ≤ 13.5%, the mass fraction ratio of tungsten to molybdenum is tungsten / molybdenum> 2.2, and the mass fraction ratio of tantalum to aluminum is tantalum / aluminum ≥ 1.1.

[0006] A further improvement of the present invention is that, in terms of mass percentage, the chemical composition of the alloy includes: 2.5wt.% to 4wt.% of chromium, 6wt.% to 9.5wt.% of cobalt, 3.5wt.% to 5wt.% of tungsten, 1wt.% to 2.5wt.% of molybdenum, 5wt.% to 6.5wt.% of rhenium, 5wt.% to 6.5wt.% of aluminum, 7wt.% to 9.5wt.% of tantalum, 0wt.% to 0.15wt.% of hafnium, 3.6wt.% to 5wt.% of ruthenium, 0wt.% to 0.03wt.% of carbon, 0wt.% to 0.02wt.% of yttrium, and the balance is nickel; and the total mass fraction of rhenium, tungsten and molybdenum in the alloy is rhenium + tungsten + molybdenum ≤ 13.0%, the mass fraction ratio of tungsten to molybdenum is tungsten / molybdenum> 2.3, and the mass fraction ratio of tantalum to aluminum is tantalum / aluminum ≥ 1.2.

[0007] A further improvement of the present invention is that the heat treatment process of the alloy comprises the following steps:

[0008] (1) Solution temperature 1340-1360°C, time 10-24h, air cooling to room temperature;

[0009] (2) Aging temperature 1100-1140°C, time 3-6h, air cooling to room temperature;

[0010] (3) Aging temperature 860-900°C, time 10-25h, air cooling to room temperature.

[0011] A further improvement of the present invention is that after the alloy is aged at 1100° C. for 1000 hours, no TCP phase is precipitated in the alloy.

[0012] A further improvement of the present invention is that the temperature bearing capacity of the alloy at 137MPa and 1000h endurance life is not less than 1100°C.

[0013] A further improvement of the present invention is that the tensile yield strength of the alloy at 1100° C. is not less than 450 MPa, and the tensile strength is not less than 500 MPa.

[0014] The main basis for the alloy composition design in the present invention is:

[0015] The main idea of ​​the alloy composition design and heat treatment in the present invention is to ensure the structural stability of the alloy during long-term service at high temperature. By synergistically regulating the content of elements that stabilize the structure and the content of elements that strongly promote the precipitation of the TCP phase, the stability of the alloy structure is guaranteed while controlling the addition of Ru, laying the foundation for the long-term high-temperature service of the alloy; at the same time, by increasing the Ta content, the stability and content of the γ′ phase under 1100°C are guaranteed. In order to ensure the economy of the alloy raw materials, the content of the precious element Ru in the alloy is limited. By high-temperature solid solution, the solid solution strengthening of the alloy elements is fully utilized and the structural differences between the dendrite trunk and the dendrites are reduced. The precipitation strengthening of the γ′ phase is fully utilized by regulating the aging process, so that the single crystal alloy with a low Re+Ru content can reach the performance level of the fifth generation single crystal.

[0016] The selection basis of the alloying element effect and composition range in the present invention is as follows:

[0017] The phase structure of the nickel-based single crystal high-temperature alloy of the present invention is a γ′ phase precipitation phase and a γ austenite phase. The content of Al and Ta in the alloy is used to maintain the volume fraction of the γ′ phase; Al is the main element of the γ′ phase and improves the oxidation resistance of the alloy, but too high a content of Al will promote the precipitation of harmful phases. The Al content of the present invention is controlled to be 5wt.% to 7wt.%. The strength and high-temperature stability of the γ′ particles are improved by Ta, and the strength of the alloy is improved by combining its solid solution strengthening. At the same time, Ta can inhibit the formation of freckle defects during casting and can improve the oxidation resistance and thermal corrosion resistance of the alloy to a certain extent; considering the alloy density factor, the present invention controls the Ta content to be 7wt.% to 10wt.%. In order to ensure the Ta content in the γ′ phase particles, the present invention controls Ta / Al≥1.1, so that the strengthening effect of the Ta element on the γ′ phase is more significant, providing support for the high endurance strength and tensile strength of the alloy.

[0018] Cr can improve the corrosion resistance and oxidation resistance of the alloy, but the solid solubility of the γ matrix is ​​limited. In a long-term high-temperature service environment, this element is very easy to combine with elements such as Mo, W, and Re to form a topological dense phase (TCP phase), which damages the high-temperature performance of the alloy. Therefore, its content needs to be coordinated so that the matrix can dissolve more elements such as Re, W, and Mo and the TCP phase is not precipitated during high-temperature service. The present invention controls the Cr content to 2.5wt.% to 4.5wt.%.

[0019] Re, W, and Mo are the main solid solution strengthening elements in the alloy. Re enriched in the γ / γ′ phase interface can effectively hinder dislocation movement and stabilize the misfit dislocation network of the phase interface. Increasing the Re content within an appropriate range has a significant effect on improving the temperature bearing capacity of nickel-based single crystal high-temperature alloys; however, Re is a rare element and is expensive, so cost factors need to be considered during the composition design process. W and Mo provide solid solution strengthening for the alloy, but their solid solution strengthening effect is not as significant as Re. However, Re, W, and Mo are all elements that promote the precipitation of TCP phase. In order to ensure the structural stability of the alloy under high temperature and long-term service, the present invention focuses on the design of the total content of Re+W+Mo. The content range of the three elements is Re: 5wt.%~6.5wt.%, W: 3wt.%~5wt.%, Mo: 1wt.%~2.8wt.%, wherein the total content of Re+W+Mo is ≤13.5%, reducing the tendency of TCP phase precipitation. After the addition of Mo element, volatile oxides are formed, resulting in reduced oxidation resistance and corrosion resistance of the alloy during ultra-long high-temperature service. In addition, W has a more significant strengthening effect on the γ′ phase than Mo. Under the condition of controlling the total content of Mo and W, the strengthening effect of W element on the γ′ phase is fully exerted by increasing the W / Mo content ratio. The present invention designs W / Mo>2.2.

[0020] Co and Ru are used as structural stabilizing elements. Among them, Co can reduce the degree of dendrite segregation of elements such as Re, W, and Mo, as well as the distribution ratio of elements in the γ and γ' phases, while increasing the solid solubility of the alloy and reducing the precipitation tendency of the TCP phase; while Ru promotes the distribution of elements such as Re, W, and Cr to the γ' phase through the "reverse distribution" effect, inhibiting the precipitation of the TCP phase, and the two elements have similar effects. However, a significant increase in the content of Co and Ru will reduce the re-dissolution temperature of the γ' phase, affect the volume fraction of the γ' phase at high temperature, and have an adverse effect on the high-temperature durability and temperature bearing capacity of the alloy. In particular, given that Ru is very expensive, a large amount of addition will increase the raw material cost of the alloy. The present invention controls the Co content to 6wt.% to 10wt.%, and the Ru content to 3.6wt.% to 5.0wt.%, wherein the Ru content is lower than the typical fifth-generation nickel-based single crystal high-temperature alloys such as TMS-162, TMS-173, and TMS-196 reported abroad, and the alloy of the present invention has good economy.

[0021] Hf can improve the fluidity and filling capacity of alloy melt, which is helpful to improve the casting performance of high-temperature alloy; however, excessive Hf will reduce the initial melting temperature of the alloy and reduce the heat treatment window of the alloy. The present invention controls the Hf content to be 0wt.% to 0.2wt.%. Rare earth Y can improve the compactness of the protective oxide film and improve the anti-oxidation performance of the alloy, and has a strong deoxidation, sulfur and phosphorus effect; however, excessive Y will react with the mold shell to form inclusions. The present invention controls the Y content to be 0wt.% to 0.03wt.%. C can effectively remove oxygen from the alloy melt to improve the smelting cleanliness. At the same time, C can improve the tolerance of the alloy's small-angle grain boundary. The present invention controls the C content to be 0wt.% to 0.05wt.%.

[0022] In the preparation process of the alloy of the present invention, the master alloy is melted and prepared in a vacuum induction melting furnace, and a single crystal test rod is prepared by directional solidification in a single crystal furnace. The pulling rate is optimized and set according to the temperature gradient range. The temperature gradient of rapid solidification is 30-80K / cm, and the pulling rate range of the single crystal alloy is 30-200μm / s. In order to reduce segregation and eliminate eutectic structure and give full play to the solid solution strengthening of alloy elements and the precipitation strengthening effect of γ′, the designed heat treatment process is: high temperature solid solution treatment in the range of 1340-1360℃ for 10-24h, air cooling to room temperature; in order to obtain the optimized γ-γ′ phase structure, then treatment in the range of 1100-1140℃ for 3-6h, air cooling to room temperature; finally treatment in the range of 860-900℃ for 10-25h, air cooling to room temperature.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) Based on the optimization of microstructure, the present invention develops a fifth-generation nickel-based single crystal high-temperature alloy with a highly stable organization. After solid solution homogenization treatment, high temperature and low temperature aging treatment, the alloy has a low tendency to precipitate TCP phase. After aging at 1100°C for 1000h, no TCP phase is precipitated. Moreover, the heat treatment process of the alloy is relatively easy to implement.

[0025] (2) The single crystal high temperature alloy in the present invention has a temperature bearing capacity reaching the level of the fifth generation single crystal high temperature alloy, and the temperature bearing capacity of 137MPa and 1000h endurance life reaches 1100℃; it has excellent endurance performance, and the endurance life is ≥1000h at 1100℃ / 137MPa, and its endurance strength is equivalent to that of the fifth generation single crystal TMS-162 alloy abroad; the alloy has a tensile yield strength of not less than 450MPa at 1100℃, and a tensile strength of not less than 500MPa, and has excellent high temperature tensile performance.

[0026] (3) The content of the precious element Ru in the alloy of the present invention is lower than that of the typical fifth-generation foreign alloys TMS-162, TMS-173, and TMS-196, so the cost is also significantly lower than the above alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the heat-treated structure of Example 2 of the present invention.

[0028] Figure 2 This is the creep test curve of the present invention at 1100°C / 137MPa.

[0029] Figure 3 It is the Larson-Miller curve (Larson-Miller curve) of the endurance life of the present invention and typical fourth-generation and fifth-generation nickel-based single crystal high-temperature alloys.

[0030] Figure 4 This is the microstructure of the nickel-based single crystal high-temperature alloy of Example 2 of the present invention after aging at 1100°C for 1000 hours.

[0031] Figure 5 This is the microstructure of the nickel-based single crystal high-temperature alloy of Example 2 of the present invention after fracture under the conditions of 1100°C / 137MPa for 1100 hours. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0033] Embodiment 1

[0034] A fifth generation nickel-based single crystal high temperature alloy with a highly stable structure, wherein the chemical composition of the alloy comprises, by mass percentage, 3.2wt.% of chromium (Cr), 8.5wt.% of cobalt (Co), 4.1wt.% of tungsten (W), 1.3wt.% of molybdenum (Mo), 6.2wt.% of rhenium (Re), 5.8wt.% of aluminum (Al), 7.5wt.% of tantalum (Ta), 0.06wt.% of hafnium (Hf), 4.4wt.% of ruthenium (Ru), 0.02wt.% of carbon (C), 0.003wt.% of yttrium (Y), and the balance is nickel (Ni); and the total mass fraction of rhenium, tungsten and molybdenum in the alloy is 11.6%, the mass fraction ratio of tungsten to molybdenum is 3.15, and the mass fraction ratio of tantalum to aluminum is 1.29.

[0035] A heat treatment process for a fifth generation nickel-based single crystal high temperature alloy with a highly stable structure comprises the following steps:

[0036] (1) Solution temperature 1350°C, time 12 h, air cooling to room temperature;

[0037] (2) Aging temperature 1100°C, time 4h, air cooling to room temperature;

[0038] (3) Aging temperature: 870°C, time: 22 h, air cooling to room temperature.

[0039] Embodiment 2

[0040] A fifth generation nickel-based single crystal high temperature alloy with a highly stable structure, wherein the chemical composition of the alloy comprises, by mass percentage, 4.0wt.% of chromium (Cr), 7.5wt.% of cobalt (Co), 4.7wt.% of tungsten (W), 2.0wt.% of molybdenum (Mo), 5.7wt.% of rhenium (Re), 6.0wt.% of aluminum (Al), 7.9wt.% of tantalum (Ta), 0.07wt.% of hafnium (Hf), 4.7wt.% of ruthenium (Ru), 0.01wt.% of carbon (C), 0.01wt.% of yttrium (Y), and the balance is nickel (Ni); and the total mass fraction of rhenium, tungsten and molybdenum in the alloy is 12.4%, the mass fraction ratio of tungsten to molybdenum is 2.35, and the mass fraction ratio of tantalum to aluminum is 1.32.

[0041] A heat treatment process for a fifth generation nickel-based single crystal high temperature alloy with a highly stable structure comprises the following steps:

[0042] (1) Solution temperature: 1340°C, solution time: 16 h, air cooling to room temperature;

[0043] (2) Aging temperature 1100°C, time 5h, air cooling to room temperature;

[0044] (3) Aging temperature: 870°C, time: 18 h, air cooling to room temperature.

[0045] Embodiment 3

[0046] A fifth generation nickel-based single crystal high temperature alloy with a highly stable structure, wherein the chemical composition of the alloy comprises, by mass percentage, 3.6wt.%, chromium (Cr), 6.4wt.%, cobalt (Co), 3.9wt.%, tungsten (W), 1.2wt.%, molybdenum (Mo), 6.3wt.%, rhenium (Re), 6.2wt.%, aluminum (Al), 8.5wt.%, tantalum (Ta), 0.05wt.%, hafnium (Hf), 4.9wt.%, ruthenium (Ru), 0.012wt.%, carbon (C), 0.02wt.%, yttrium (Y), and the balance nickel (Ni); and the total mass fraction of rhenium, tungsten and molybdenum in the alloy is 11.4%, the mass fraction ratio of tungsten to molybdenum is 3.25, and the mass fraction ratio of tantalum to aluminum is 1.37.

[0047] A heat treatment process for a fifth generation nickel-based single crystal high temperature alloy with a highly stable structure comprises the following steps:

[0048] (1) Solution temperature: 1345°C, solution time: 15 h, air cooling to room temperature;

[0049] (2) Aging temperature: 1120°C, time: 6 h, air cooling to room temperature;

[0050] (3) Aging temperature: 880°C, time: 12 h, air cooling to room temperature.

[0051] Embodiment 4

[0052] A fifth generation nickel-based single crystal high temperature alloy with a highly stable structure. The chemical composition of the alloy comprises, by mass percentage, 2.8wt.%, chromium (Cr), 6.9wt.%, cobalt (Co), 4.3wt.%, tungsten (W), 1.6wt.%, molybdenum (Mo), 6.1wt.%, rhenium (Re), 6.0wt.%, aluminum (Al), 8.2wt.%, tantalum (Ta), 0.08wt.%, hafnium (Hf), 4.5wt.%, ruthenium (Ru), 0wt.%, carbon (C), 0.025wt.%, yttrium (Y), and the balance nickel (Ni). The total mass fraction of rhenium, tungsten and molybdenum in the alloy is 12%, the mass fraction ratio of tungsten to molybdenum is 2.69, and the mass fraction ratio of tungsten to aluminum is 1.37.

[0053] A heat treatment process for a fifth generation nickel-based single crystal high temperature alloy with a highly stable structure comprises the following steps:

[0054] (1) Solution temperature: 1355°C, solution time: 13 h, air cooling to room temperature;

[0055] (2) Aging temperature: 1120°C, time: 3 h, air cooling to room temperature;

[0056] (3) Aging temperature: 880°C, time: 12 h, air cooling to room temperature.

[0057] Embodiment 5

[0058] A fifth generation nickel-based single crystal high temperature alloy with a highly stable structure. The chemical composition of the alloy comprises, by mass percentage, 3.0wt.% of chromium (Cr), 8.4wt.% of cobalt (Co), 4.1wt.% of tungsten (W), 1.4wt.% of molybdenum (Mo), 5.8wt.% of rhenium (Re), 5.5wt.% of aluminum (Al), 8.7wt.% of tantalum (Ta), 0.05wt.% of hafnium (Hf), 4.6wt.% of ruthenium (Ru), 0.03wt.% of carbon (C), 0wt.% of yttrium (Y), and the remainder is nickel (Ni). The total mass fraction of rhenium, tungsten and molybdenum in the alloy is 11.3%, the mass fraction ratio of tungsten to molybdenum is 2.93, and the mass fraction ratio of tantalum to aluminum is 1.58.

[0059] A heat treatment process for a fifth generation nickel-based single crystal high temperature alloy with a highly stable structure comprises the following steps:

[0060] (1) Solution temperature: 1348°C, solution time: 19 h, air cooling to room temperature;

[0061] (2) Aging temperature: 1110°C, time: 5 h, air cooling to room temperature;

[0062] (3) Aging temperature: 870°C, time: 20 h, air cooling to room temperature.

[0063] Comparative Example 1

[0064] A high-generation nickel-based single crystal high-temperature alloy, the chemical composition of which, by mass percentage, includes: chromium (Cr) 4.3wt.%, cobalt (Co) 6.2wt.%, tungsten (W) 4.9wt.%, molybdenum (Mo) 2.6wt.%, rhenium (Re) 6.5wt.%, aluminum (Al) 5.8wt.%, tantalum (Ta) 7.5wt.%, hafnium (Hf) 0.1wt.%, ruthenium (Ru) 4.5wt.%, carbon (C) 0.02wt.%, yttrium (Y) 0.02wt.%, and the balance nickel (Ni). The total mass fraction of rhenium, tungsten and molybdenum in the alloy is 14%, the mass fraction ratio of tungsten to molybdenum is 1.88, and the mass fraction ratio of tantalum to aluminum is 1.29.

[0065] A heat treatment process for a high-generation nickel-based single crystal high-temperature alloy comprises the following steps:

[0066] (1) Solution temperature: 1340°C, solution time: 16 h, air cooling to room temperature;

[0067] (2) Aging temperature 1100°C, time 5h, air cooling to room temperature;

[0068] (3) Aging temperature: 870°C, time: 18 h, air cooling to room temperature.

[0069] Comparative Example 2

[0070] A high-generation nickel-based single crystal high-temperature alloy, the chemical composition of which, by mass percentage, includes: 4.6wt.% of chromium (Cr), 6.5wt.% of cobalt (Co), 5.0wt.% of tungsten (W), 2.5wt.% of molybdenum (Mo), 6.8wt.% of rhenium (Re), 5.6wt.% of aluminum (Al), 5.6wt.% of tantalum (Ta), 0.15wt.% of hafnium (Hf), 5.0wt.% of ruthenium (Ru), 0.03wt.% of carbon (C), 0.01wt.% of yttrium (Y), and the balance of nickel (Ni). The total mass fraction of rhenium, tungsten and molybdenum in the alloy is 14.3%, the mass fraction ratio of tungsten to molybdenum is 2, and the mass fraction ratio of tantalum to aluminum is 1.

[0071] A heat treatment process for a high-generation nickel-based single crystal high-temperature alloy comprises the following steps:

[0072] (1) Solution temperature: 1340°C, solution time: 16 h, air cooling to room temperature;

[0073] (2) Aging temperature 1100°C, time 5h, air cooling to room temperature;

[0074] (3) Aging temperature: 870°C, time: 18 h, air cooling to room temperature.

[0075] Comparative Example 3

[0076] The fourth generation nickel-based single crystal high temperature alloy TMS-138, in terms of mass percentage, has a chemical composition comprising: chromium (Cr) 3.2wt.%, cobalt (Co) 5.8wt.%, tungsten (W) 5.9wt.%, molybdenum (Mo) 2.9wt.%, rhenium (Re) 5.0wt.%, aluminum (Al) 5.8wt.%, tantalum (Ta) 5.6wt.%, hafnium (Hf) 0.1wt.%, ruthenium (Ru) 2.0wt.%, and the balance nickel (Ni). The total mass fraction of rhenium, tungsten and molybdenum in the alloy is 13.8%, the mass fraction ratio of tungsten to molybdenum is 2.03, and the mass fraction ratio of tantalum to aluminum is 0.97.

[0077] Comparative Example 4

[0078] The fifth generation nickel-based single crystal high temperature alloy TMS-162, in terms of mass percentage, has a chemical composition comprising: chromium (Cr) 3.0wt.%, cobalt (Co) 5.8wt.%, tungsten (W) 5.8wt.%, molybdenum (Mo) 3.9wt.%, rhenium (Re) 4.9wt.%, aluminum (Al) 5.8wt.%, tantalum (Ta) 5.6wt.%, hafnium (Hf) 0.1wt.%, ruthenium (Ru) 6.0wt.%, and the balance nickel (Ni). The total mass fraction of rhenium, tungsten and molybdenum in the alloy is 14.6%, the mass fraction ratio of tungsten to molybdenum is 1.49, and the mass fraction ratio of tantalum to aluminum is 0.97.

[0079] Comparative Example 5

[0080] The fifth generation nickel-based single crystal high temperature alloy TMS-173, in terms of mass percentage, has a chemical composition comprising: chromium (Cr) 3.0wt.%, cobalt (Co) 5.8wt.%, tungsten (W) 5.6wt.%, molybdenum (Mo) 2.8wt.%, rhenium (Re) 6.9wt.%, aluminum (Al) 5.6wt.%, tantalum (Ta) 5.6wt.%, hafnium (Hf) 0.1wt.%, ruthenium (Ru) 5.0wt.%, and the balance nickel (Ni). The total mass fraction of rhenium, tungsten and molybdenum in the alloy is 15.3%, the mass fraction ratio of tungsten to molybdenum is 2, and the mass fraction ratio of tantalum to aluminum is 1.

[0081] Compared with typical high-generation nickel-based single crystal high-temperature alloys, the design concept and composition characteristics of this alloy have significantly different characteristics.

[0082] Table 1 below shows the endurance of five embodiments and five comparative embodiments at 1100°C / 137MPa. The single crystal high temperature alloy of the present invention has a longer endurance under high temperature and low stress conditions.

[0083] As shown in Table 1, the endurance life of the alloy of the present invention at 1100°C / 137MPa is significantly improved compared with that of the fourth-generation alloy, and is comparable to that of the typical fifth-generation alloy.

[0084] Figure 2 The creep test curve of the selected Example 2 at 1100°C / 137MPa is given. The alloy undergoes creep rupture after 1106h, which exceeds the level of some reported fifth-generation single crystals.

[0085] Figure 3 The Larson-Miller curves of the endurance performance of the selected Example 2 and two comparative examples of nickel-based single crystal high-temperature alloys are given. It can be seen that within a wide temperature and stress range, the endurance performance of the invention alloy is greatly improved compared with the fourth-generation nickel-based single crystal alloy, and is comparable to the endurance life level of the typical fifth-generation nickel-based single crystal high-temperature alloy. It has certain advantages in the high temperature section, and it can be inferred that the temperature bearing capacity of Example 2 is above 1100°C.

[0086] Table 1 1100℃ / 137MPa rupture life of alloys in the present invention and comparative examples

[0087] Alloy Name Durability (h) Embodiment 1 1025 Embodiment 2 1106 Embodiment 3 1039 Embodiment 4 1007 Embodiment 5 1010 Comparative Example 1 718 Comparative Example 2 554 Comparative Example 3 399 Comparative Example 4 1060 Comparative Example 5 970

[0088] Table 2 shows the temperature-bearing capacity of the single crystal high-temperature alloy of alloy embodiment 2 of the present invention and some typical nickel-based single crystal high-temperature alloys. Under the conditions of 137MPa and 1000h endurance life, the present invention has outstanding temperature-bearing capacity, which is significantly improved over the third and fourth generation single crystal high-temperature alloys and is equivalent to the fifth generation nickel-based single crystal high-temperature alloy.

[0089] From the above, it can be seen that the alloy of the present invention has a relatively high temperature bearing capacity and is suitable for application in hot end components such as advanced aircraft engines with a high thrust-to-weight ratio.

[0090] Table 2 Temperature bearing capacity of the alloy of the present invention and the reference alloy (temperature bearing capacity under 137MPa, 1000h endurance life condition)

[0091] Alloy Name Temperature bearing capacity (℃) Embodiment 1 1102 Embodiment 2 1105 Embodiment 3 1103 Embodiment 4 1101 Embodiment 5 1100 Comparative Example 1 1088 Comparative Example 2 1086 Comparative Example 3 1083 Comparative Example 4 1106 Comparative Example 5 1099

[0092] Figure 4 , Figure 5The microstructure of the nickel-based single crystal high-temperature alloy of Example 2 of the present invention after aging at 1100°C for 1000 h and the microstructure after fracture under 1100°C / 137 MPa endurance conditions for 1100 h are given. No TCP phase precipitation phenomenon is found in the microstructure. The alloy of the present invention has a low tendency to precipitate TCP phase and has high organizational stability.

[0093] Table 3 1100℃ high temperature tensile properties of the alloy of the present invention

[0094] Alloy Name Yield strength (MPa) Tensile strength(MPa) Embodiment 1 455 531 Embodiment 2 471 545 Embodiment 3 503 563 Embodiment 4 486 556 Embodiment 5 475 532

[0095] Table 3 shows the high temperature tensile properties of the alloy of the present invention at 1100°C. The yield strength of the selected example alloy at this temperature is not less than 450 MPa, and the tensile strength is not less than 500 MPa. The alloy of the present invention has excellent high temperature tensile properties.

[0096] The above specific implementation modes are used to explain the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A fifth generation nickel-based single crystal high temperature alloy with a highly stable structure, characterized in that: The chemical composition of the alloy comprises, by mass percentage, 2.5wt%-4.5wt.%, 6wt.%-10wt.%, tungsten 3wt.%-5wt.%, molybdenum 1wt.%-2.8wt.%, rhenium 5wt.%-6.5wt.%, aluminum 5wt.%-7wt.%, tantalum 7wt.%-10wt.%, hafnium 0wt.%-0.2wt.%, ruthenium 3.6wt.%-5wt.%, carbon 0wt.%-0.05wt.%, yttrium 0wt.%-0.03wt.%, and the balance nickel; and the total mass fraction of rhenium, tungsten and molybdenum in the alloy is rhenium+tungsten+molybdenum≤13.5%, the mass fraction ratio of tungsten to molybdenum is tungsten / molybdenum>2.2, and the mass fraction ratio of tantalum to aluminum is tantalum / aluminum≥1.

1.

2. The fifth generation nickel-based single crystal high temperature alloy with a highly stable structure according to claim 1, characterized in that: The chemical composition of the alloy includes, by mass percentage, 2.5wt%-4wt% of chromium, 6wt%-9.5wt% of cobalt, 3.5wt%-5wt% of tungsten, 1wt%-2.5wt% of molybdenum, 5wt%-6.5wt% of rhenium, 5wt%-6.5wt% of aluminum, 7wt%-9.5wt% of tantalum, 0wt%-0.15wt% of hafnium, 3.6wt%-5wt% of ruthenium, 0wt%-0.03wt% of carbon, 0wt%-0.02wt% of yttrium, and the balance of nickel; and the total mass fraction of rhenium, tungsten and molybdenum in the alloy is rhenium+tungsten+molybdenum≤13.0%, the mass fraction ratio of tungsten to molybdenum is tungsten / molybdenum>2.3, and the mass fraction ratio of tantalum to aluminum is tantalum / aluminum≥1.

2.

3. The fifth generation nickel-based single crystal high temperature alloy with a highly stable structure according to claim 1, characterized in that: The heat treatment process of the nickel-based single crystal high-temperature alloy comprises the following steps: (1) Solution temperature 1340-1360°C, time 10-24h, air cooling to room temperature; (2) Aging temperature 1100-1140°C, time 3-6h, air cooling to room temperature; (3) Aging temperature 860-900°C, time 10-25h, air cooling to room temperature.

4. The fifth generation nickel-based single crystal high temperature alloy with a highly stable structure according to claim 3, characterized in that: After the alloy is aged at 1100° C. for 1000 h, no TCP phase is precipitated in the alloy.

5. The fifth generation nickel-based single crystal high temperature alloy with a highly stable structure according to claim 3, characterized in that: The temperature bearing capacity of the alloy at 137MPa and 1000h endurance life is not less than 1100℃.

6. The fifth generation nickel-based single crystal high temperature alloy with a highly stable structure according to claim 3, characterized in that: Under the condition of 1100℃ / 137MPa, the alloy has a durability life of not less than 1000h.

7. The fifth generation nickel-based single crystal high temperature alloy with a highly stable structure according to claim 3, characterized in that: The tensile yield strength of the alloy at 1100°C is not less than 450MPa, and the tensile strength is not less than 500MPa.

Images