High-Temperature Alloys

What Is High-Temperature Alloys

High-temperature alloy refers to a type of metal material based on iron, nickel, and cobalt that can work for a long time at a high temperature above 600 ℃ and a certain stress. It has excellent high temperature strength, good oxidation and thermal corrosion resistance, and good Its fatigue performance, fracture toughness and other comprehensive properties, also known as “super alloys,” are mainly used in the aerospace and energy fields.

The superalloy is a single austenitic structure, which has good structure stability and service reliability at various temperatures.

Based on the above-mentioned performance characteristics, and the high degree of alloying of superalloys, it is also called “superalloys”. It is an important material widely used in aviation, aerospace, petroleum, chemical industry, and ships. According to the matrix elements, superalloys are divided into iron-based, nickel-based, cobalt-based and other high-temperature alloys. The service temperature of iron-based superalloys generally can only reach 750~780℃. For heat-resistant parts used at higher temperatures, nickel-based and refractory metal-based alloys are used. Nickel-based superalloy occupies a particularly important position in the entire field of superalloys. It is widely used to manufacture the hottest parts of aviation jet engines and various industrial gas turbines.

The Development History Of Superalloys

1. International development

Since the late 1930s, Britain, Germany, the United States and other countries have begun to study superalloys. During the Second World War, in order to meet the needs of new aero-engines, the research and use of superalloys entered a period of vigorous development. In the early 1940s, Britain first added a small amount of aluminum and titanium to 80Ni-20Cr alloy to form a γ’phase for strengthening, and developed the first nickel-based alloy with higher high temperature strength. In the same period, the United States began to use Vitallium cobalt-based alloys to make blades in order to meet the needs of the development of turbochargers for piston aviation engines.

In addition, the United States has also developed Inconel nickel-based alloys to make jet engine combustion chambers. Later, in order to further improve the high temperature strength of the alloy, metallurgists added tungsten, molybdenum, cobalt and other elements to the nickel-based alloy to increase the content of aluminum and titanium, and developed a series of alloys, such as the British “Nimonic” and the American “Mar-M” and “IN”, etc.; In the cobalt-based alloy, nickel, tungsten and other elements are added to develop a variety of high-temperature alloys, such as X-45, HA-188, FSX-414, etc. Due to the lack of cobalt resources, the development of cobalt-based superalloys is restricted.

In the 1940s, iron-based superalloys were also developed. In the 1950s, brands such as A-286 and Incoloy901 appeared. However, due to poor high-temperature stability, the development has been slow since the 1960s. The Soviet Union began to produce “ЭИ” brand nickel-based superalloys around 1950, and later produced “ЭП” series of deformed superalloys and ЖС series of cast superalloys. In the 1970s, the United States also adopted new production processes to manufacture directional crystal blades and powder metallurgy turbine disks, and developed single crystal blades and other high-temperature alloy components to meet the needs of increasing temperature at the inlet of aero-engine turbines.

Since its development, the annual consumption of high-temperature metal alloys in the international market is 300,000 tons, which are widely used in various fields. In the past few years, the global aerospace industry has a strong demand for new energy aircraft, and Airbus and Boeing have more than 10,000 such aircraft waiting for delivery. The Precision Parts Company is a global leader in the manufacture of high-temperature alloy complex metal parts and products. It also provides nickel-cobalt and other high-temperature alloys required by industries such as aerospace, chemical processing, oil and gas smelting, and pollution prevention. Precision Parts Company is the designated manufacturer of parts for military and aerospace companies such as Boeing, Airbus, Rolls Royce, and Bombardier

2. China’s development

Since the successful trial of the first furnace of superalloy GH3030 in 1956, the research, production and application of superalloys in China have gone through 60 years of development so far. The 60-year development of superalloys can be divided into three stages.

The first stage: from 1956 to the early 1970s was the entrepreneurial and initial stage of China’s superalloys. This stage is mainly to imitate the alloy series of former Soviet Union high-temperature alloy as the main body, such as: GH4033, GH4049, GH2036, GH3030, K401 and K403, etc.

The second stage: from the mid-1970s to the mid-1990s, is the improvement phase of China’s superalloys. The main stage is to trial-produce European and American models of engines to improve the production technology of superalloys and product quality control.

The third stage: from the mid-1990s to the present, it is a new development stage of China’s superalloys. At this stage, a batch of new processes have been applied and developed, and a series of high-performance and high-grade new alloys have been developed and produced.

The main research units of China’s superalloy research are the Central Iron and Steel Research Institute, Beijing Institute of Aeronautical Materials, Institute of Metal Research, Chinese Academy of Sciences, University of Science and Technology Beijing, Northeastern University, Northwestern Polytechnical University, etc. The main manufacturers are: AVIC, Steel Research Gona , Shizhu Nonferrous Metals, Fushun Special Steel, Gaogang Special Steel and Wanhang Mould Forging Plant (Erzhong) of the Second Heavy Machinery Group. On this basis, China has the capability of independent R&D and research on new materials and new processes for superalloys.
Although high-temperature metal alloy materials have been developed in China for nearly 60 years, the development of the industry is still in the growth stage. Due to the high technical content in the field of high-temperature metal alloy materials, enterprises in this industry have a deep moat. The annual demand for high-temperature metal alloys in China is more than 20,000 tons, and the annual production volume in China is about 10,000 tons. The market capacity exceeds 8 billion yuan, of which imports account for a relatively large proportion. In the next 20 years, China’s procurement demand for various military aircraft will be about 2,800, and the number of civilian aircraft procurement will be about 5,400. The corresponding demand for superalloys will be more than 150 billion. In addition to the demand for gas turbines of 50 billion, there will be space for superalloys alone. The 200 billion market space is about to open.

There are two gaps between China’s production capacity and demand:

• Insufficient production capacity. The number of high-temperature alloy manufacturers in China is limited, and there is a large gap between production capacity and demand. High-temperature alloys in the fields of gas turbines and nuclear power mainly rely on imports.
• High-end products are difficult to meet application requirements. There is a big gap between China’s high-temperature alloy production level and the United States, Russia and other countries. As China develops higher-performance aerospace engines, the supply of high-temperature alloy materials cannot meet application needs.

The Preparation Process Of High-Temperature Alloys

1. Foundry metallurgical process

Various advanced casting manufacturing technologies and processing equipment are constantly being developed and improved, such as thermal control solidification, fine-grain technology, laser forming repair technology, wear-resistant casting casting technology, etc. The original technical level is continuously improved to improve various high-temperature alloy castings Product quality consistency and reliability.

High-temperature alloys that do not contain or contain aluminum or titanium are generally smelted in electric arc furnaces or non-vacuum induction furnaces. When high-temperature alloys containing high aluminum and titanium are smelted in the atmosphere, element burning is not easy to control, and more gas and inclusions enter, so vacuum smelting should be used. In order to further reduce the content of inclusions and improve the distribution of inclusions and the crystalline structure of the ingot, a dual process combining smelting and secondary remelting can be used. The main means of smelting are electric arc furnace, vacuum induction furnace and non-vacuum induction furnace; the main means of remelting are vacuum consumable furnace and electroslag furnace.

Solid solution strengthened alloys and alloy ingots containing low aluminum and titanium (the total amount of aluminum and titanium is less than 4.5%) can be forged to billet; alloys containing aluminum and high titanium generally need to be extruded or rolled to billet. Then hot-rolled into lumber, some products need to be further cold-rolled or cold-drawn. Larger diameter alloy ingots or cakes need to be forged with hydraulic press or quick forging hydraulic press.

2. Crystallization metallurgy process

In order to reduce or eliminate the grain boundary perpendicular to the stress axis in the cast alloy and reduce or eliminate the porosity, the directional crystallization process has been developed in recent years. This process is to make crystal grains grow along a crystalline direction during the solidification of the alloy to obtain parallel columnar crystals without lateral grain boundaries. The first process condition to achieve directional crystallization is to establish and maintain a sufficiently large axial temperature gradient and good axial heat dissipation conditions between the liquidus line and the solidus line. In addition, in order to eliminate all grain boundaries, it is necessary to study the manufacturing process of single crystal blades.

3. Powder metallurgy process

Powder metallurgy technology is mainly used to produce precipitation-strengthened and oxide dispersion-strengthened superalloys. This process can make the generally indeformable cast high-temperature alloy obtain plasticity or even superplasticity.

4. Strength improvement process

⑴Solid solution strengthening

The addition of elements (chromium, tungsten, molybdenum, etc.) with different atomic sizes from the base metal causes the distortion of the base metal lattice, the addition of elements that can reduce the stacking fault energy of the alloy matrix (such as cobalt) and the addition of elements that can slow down the diffusion rate of the matrix elements Elements (tungsten, molybdenum, etc.) to strengthen the matrix.

⑵ Precipitation strengthening

Through aging treatment, the second phase (γ’, γ”, carbides, etc.) is precipitated from the supersaturated solid solution to strengthen the alloy. The γ’phase is the same as the matrix, with a face-centered cubic structure, and the lattice constant is similar to that of the matrix. And coherent with the crystal, so the γ phase can be uniformly precipitated in the form of fine particles in the matrix, which hinders the movement of dislocations and produces a significant strengthening effect. γ’phase is an A3B type intermetallic compound, A represents nickel and cobalt, and B represents Aluminum, titanium, niobium, tantalum, vanadium, and tungsten, while chromium, molybdenum, and iron can be either A or B. The typical γ’phase in nickel-based alloys is Ni3 (Al, Ti).

The strengthening effect of γ’ phase can be strengthened through the following ways:

• Increase the number of γ’phases;
• Make the γ’phase and the matrix have an appropriate degree of mismatch to obtain the strengthening effect of coherent distortion;
• Adding niobium, tantalum and other elements to increase the antiphase domain boundary energy of γ’phase to improve its resistance to dislocation cutting;
• Adding cobalt, tungsten, molybdenum and other elements to improve the strength of the γ’phase. The γ” phase is a body-centered tetragonal structure, and its composition is Ni3Nb. Because the γ” phase has a large mismatch with the matrix, it can cause a large degree of coherent distortion, and the alloy obtains a high yield strength. However, if the temperature exceeds 700°C, the strengthening effect is significantly reduced. Cobalt-based superalloys generally do not contain γ phase, but are strengthened with carbides.

The Material Properties Of Superalloys

Various degradation speeds of materials are accelerated in high-temperature environments, and the organization is prone to instability, deformation and crack growth under the action of temperature and stress, and oxidation and corrosion of the material surface during use.

1. High temperature resistance and corrosion resistance

The high temperature resistance, corrosion resistance and other properties of superalloys mainly depend on its chemical composition and organizational structure. Taking GH4169 nickel-base deformed superalloy as an example, it can be seen that the niobium content in GH4169 alloy is high, and the degree of niobium segregation in the alloy is directly related to the metallurgical process. The matrix of GH4169 is Ni-Gr solid solution, and the content of Ni can withstand more than 50%. The high temperature is about 1 000℃, similar to the American brand Inconel718. The alloy consists of γ matrix phase, δ phase, carbide and strengthening phase γ’and γ″ phase. The chemical elements and matrix structure of GH4169 alloy show its strong mechanical properties. Yield strength and tensile strength are several times better than 45 steel, and plasticity is also better than 45 steel. The stable lattice structure and a large number of strengthening factors construct its excellent mechanical properties.

Ni	Cr	Mo	Ti	Nb	A l	Fe
51． 96	17． 98	3． 07	0． 95	4． 82	0． 45	etc

2. High processing difficulty

Due to its complex and harsh working environment, the integrity of the processed surface of superalloys plays a very important role in the performance of its performance. However, superalloy is a typical difficult-to-machine material. Its micro-strengthening item has high hardness, severe work hardening, and it has high shear stress resistance and low thermal conductivity. The cutting force and cutting temperature in the cutting area are high, which often occurs during processing. The quality of the machined surface is low, and the tool breakage is very serious. Under general cutting conditions, the surface layer of the superalloy will produce excessive problems such as hardened layer, residual stress, white layer, black layer, and grain deformation layer.

The Main Classification Of High-Temperature Alloys

The traditional classification of superalloy materials can be carried out according to the following three methods: according to the type of matrix element, alloy strengthening type, and material forming method.

1. According to the type of matrix element

⑴Iron-based superalloy

Iron-based superalloys can also be called heat-resistant alloy steels. Its matrix is ​​Fe element, adding a small amount of alloying elements such as Ni, Cr, heat-resistant alloy steel can be divided into martensite, austenite, pearlite, ferritic heat-resistant steel, etc. according to its normalizing requirements.

⑵Nickel-based superalloy

Nickel-based superalloys contain more than half of the nickel and are suitable for working conditions above 1,000°C. The solid solution and aging process can greatly improve the creep resistance and compressive yield strength. In terms of high-temperature alloys used in high-temperature environments, the use of nickel-based superalloys far exceeds the use of iron-based and cobalt-based superalloys. At the same time, nickel-based superalloys are also the largest and most used superalloy in my country. Many turbine blades and combustion chambers of turbine engines, and even turbochargers also use nickel-based alloys as preparation materials. For more than half a century, the ability of high temperature materials used in aeroengines to withstand high temperatures has increased from 750°C in the late 1940s to 1,200°C in the late 1990s. It should be said that this huge improvement has also prompted the casting process and surface coating. Rapid development in other areas.

⑶ Cobalt-based superalloys

Cobalt-based superalloys are based on cobalt, and the content of cobalt is about 60%. At the same time, elements such as Cr and Ni need to be added to improve the heat resistance of the superalloy. Although this superalloy has better heat resistance, it is due to various countries The output of cobalt resources is relatively small and the processing is relatively difficult, so the amount of cobalt resources is not large. It is usually used in high temperature conditions (600 ～ 1 000℃) and high temperature components subject to extreme complex stress for a long time, such as the working blades of aero engines, turbine discs, hot end parts of combustion chambers and aerospace engines. In order to obtain better heat resistance, under normal conditions, elements such as W, MO, Ti, Al, Co should be added during preparation to ensure its superior thermal fatigue resistance.

2. Alloy strengthening type

According to the type of alloy strengthening, superalloys can be divided into solid solution strengthened superalloys and aging precipitation strengthened alloys.

⑴Solid solution strengthening type

The so-called solid solution strengthening type means adding some alloying elements to iron, nickel or cobalt-based superalloys to form a single-phase austenite structure. The solute atoms deform the solid solution matrix lattice and increase the sliding resistance in the solid solution for strengthening. Some solute atoms can reduce the stacking fault energy of the alloy system and increase the tendency of dislocation decomposition, making it difficult for cross-slip to proceed, and the alloy is strengthened to achieve the purpose of strengthening the superalloy.

⑵Aging precipitation strengthening

The so-called aging precipitation strengthening refers to a heat treatment process in which the alloy workpiece is solid-solution treated and cold plastically deformed, and then placed at a higher temperature or at room temperature to maintain its performance. For example: GH4169 alloy has a maximum yield strength of 1 000 MPa at 650℃, and the alloy temperature for making blades can reach 950℃.

3. Material molding method

Divided by material forming methods: casting superalloys (including ordinary casting alloys, single crystal alloys, oriented alloys, etc.), deformed superalloys, powder metallurgy superalloys (including ordinary powder metallurgy and oxide dispersion strengthened superalloys).

⑴Casting superalloy

The alloy material that uses the casting method to directly prepare the parts is called the casting superalloy. According to the composition of the alloy matrix, it can be divided into three types: iron-based casting superalloys, nickel-based casting superalloys and drill-based casting superalloys. According to the crystallization method, it can be divided into four types: polycrystalline casting superalloys, directional solidification casting superalloys, directional eutectic casting superalloys and single crystal casting superalloys.

⑵Wrought superalloy

It is still the most used material in aero-engines and is widely used at home and abroad. The annual output of deformed superalloys in my country is about 1/8 of that of the United States [2]. Take GH4169 alloy as an example, it is one of the main varieties with the most applications at home and abroad. In my country, the bolts, compressors, wheels, and oil slingers of turboshaft engines are mainly used as main parts. With the maturity of other alloy products, the use of deformed superalloys may gradually decrease, but it will still be in the next few decades. Dominant.

⑶ New type of superalloy

Including powder superalloys, titanium-aluminum intermetallic compounds, oxide dispersion-strengthened superalloys, corrosion-resistant superalloys, powder metallurgy and nano-materials and other subdivided product fields.

• ①The degree of alloying of the third-generation powder superalloy has been increased, which allows it to take into account the advantages of the previous two generations, and obtains higher strength and lower damage. The powder superalloy production process is becoming more mature, and the following aspects may be developed in the future : Powder preparation, heat treatment process, computer simulation technology, dual performance powder tray;
• ②Titanium-aluminum intermetallic compounds have been developed to the fourth generation, and are gradually expanding in the two directions of multi-element micro-element and a large number of microelement. The University of Hamburg in Germany, Kyoto University in Japan, and the GKSS Center in Germany have all conducted extensive research. Aluminum-based intermetallic compounds have now been used in the fields of ships, biomedical products, and sporting goods;
• ③Oxide dispersion-strengthened superalloys are part of powdered superalloys. There are nearly 20 kinds of them under production. They have high high-temperature strength and low stress coefficient. They are widely used in heat-resistant and anti-oxidation parts of gas turbines, advanced aero-engines, Petrochemical reactors, etc.;
• ④ Corrosion-resistant high-temperature alloys are mainly used to replace refractory materials and heat-resistant steels, and are used in construction and aerospace fields.

The Common Types Of High-Temperature Alloys

1. GH4169 high temperature alloy

GH4169 alloy is a nickel-chromium-iron-based high-temperature alloy. GH4169 alloy is a nickel-based deformed high-temperature alloy. Nickel-based alloys are one of the most complex alloys. It is widely used in the manufacture of various high-temperature components. At the same time, it is also the most eye-catching alloy among all high-temperature alloys. Its relative service temperature is also the highest among all common alloy series. The proportion of this alloy in advanced aircraft engines is more than 50%.

GH4169 alloy was successfully developed by Eiselstein of Huntington Branch of the International Nickel Corporation. It was an age-hardening nickel-chromium-iron-based deformation alloy that was publicly introduced in 1995. The alloy is a kind of nickel-based deformed superalloy with body-centered cubic g” and face-centered cubic g’phase as precipitation strengthening. It has high tensile strength, yield strength and good plasticity below 650℃, and has good corrosion resistance. , Radiation resistance, fatigue, fracture toughness and other comprehensive properties, as well as satisfactory welding and post-weld forming properties, etc. The alloy has stable structure and performance in a wide temperature range of -253 ~ 650 ℃, and becomes the use under deep cold and high temperature conditions. A wide range of superalloys. Due to the good comprehensive performance of GH4169, it is widely used in aero-engine compressor discs, compressor shafts, compressor blades, turbine discs, turbine shafts, casings, fasteners and other structural parts and plates Welding parts, etc. [3].
Our country began to develop GH4169 alloy in the 1970s, which is mainly used in discs and has a relatively short use time. Therefore, the double process of vacuum induction and electroslag remelting is adopted. It began to be applied in the aviation field in the 1980s. Improving and improving the quality of materials, and improving the overall performance and reliability of alloys have become the main research directions. The current main research directions of GH4169 alloy are:

• Improve the smelting process, quantify the smelting parameters, realize the stable operation of the program, and make the alloy microstructure more uniform, so as to obtain excellent yield and fatigue strength, anti-crack propagation and crack arrest capabilities, and improve low-cycle fatigue strength;
• Improve the heat treatment process. The heat treatment process cannot well eliminate the segregation in the center of the steel ingot, so it has an adverse effect on the uniformity of the structure. Therefore, using a reasonable homogenization annealing process to obtain fine-grained blanks has become one of the main research directions;
• Improve the use design. Since the working temperature of GH4169 cannot be higher than 650℃, the cooling of parts should be strengthened to give full play to the high-performance and low-cost advantages of this superalloy;
• Improve the stability of the organization. Due to the long-life requirements of aero-engine components, it is also crucial to improve the long-term aging structure stability of GH4169 alloy.

2. Single crystal superalloy

Single crystal alloy materials have been developed to the fourth generation, and the temperature-bearing capacity has increased to 1140°C, which is close to the use temperature limit of metal materials. In the future, to further meet the needs of advanced aero-engines, the development of blade materials needs to be further expanded, and ceramic matrix composite materials are expected to replace single crystal superalloys to meet the use of hot-end components in higher temperature environments.

The development difficulty and cycle of single crystal superalloy blades are related to their structural complexity. The development cycle of single crystal blades of ordinary complexity is relatively short, but it takes a long time to be applied to aero engines. From single crystal solid blades to single crystal hollow blades to high-efficiency air-cooled complex hollow blades, the technical difficulty spans a large span, and the corresponding development cycle span is also large. Generally, it takes 1 to 2 years for a single crystal hollow blade of ordinary complexity to confirm drawings, mold design, trial production, and then to small batch production. However, due to the complex service environment of single crystal blades, a large number of verification tests are required. Generally, it takes 5 to 10 years for a single crystal hollow blade with a common structure to be applied to aero engines after being developed, and some are developed with the engine. Progress, it may even take 15 years or more

The Main Applications Of Superalloys

1. Aerospace

The development of my country’s independent aerospace industry to develop advanced engines will increase the market’s demand for high-end and new superalloys.

The aero engine is called “the flower of industry”, and it is one of the most technical and difficult components in the aviation industry. As the aero engine of the aircraft power plant, it is particularly important that the metal structural material has the properties of light weight, high strength, high toughness, high temperature resistance, oxidation resistance, and corrosion resistance. This is almost the highest performance requirement among structural materials.

Superalloy is a metal material that can work for a long time under a certain stress condition above 600℃. High-temperature alloys are developed to meet the demanding requirements of modern aero-engines, and have become an irreplaceable key material for the hot-end parts of aero-engines. In advanced aero-engines, the proportion of superalloys used has reached more than 50%.
In modern advanced aeroengines, the amount of superalloy materials accounts for 40% to 60% of the total amount of the engine. In aero-engines, high-temperature alloys are mainly used in the four hot sections of combustion chambers, guide vanes, turbine blades and turbine discs; in addition, they are also used in parts such as casings, rings, afterburners and tail nozzles.

2. Energy field

Superalloys have a wide range of applications in the energy field. In the high-parameter ultra-supercritical power generation boiler for coal power, the superheater and re-superheater must use high-temperature alloy pipes with good creep resistance, oxidation resistance on the steam side and corrosion resistance on the flue gas side; in gas and power applications In gas turbines, turbine blades and guide blades need to use high-temperature corrosion-resistant high-temperature alloys with excellent high-temperature corrosion resistance and long-term stable organization; in the field of nuclear power, steam generator heat transfer tubes must use high-temperature alloys with good solution corrosion resistance; in coal In the field of gasification and energy saving and emission reduction, high-temperature alloys with excellent resistance to high-temperature thermal corrosion and high-temperature abrasion are widely used; in oil and natural gas exploitation, especially in deep well exploitation, drilling tools are in an acidic environment of 4-150 ℃, plus For the presence of CO2, H2S, and sand, corrosion-resistant and wear-resistant high-temperature alloys must be used.

my country’s Shanghai Electric, Dongfang Electric, Harbin Steam Turbine Factory and other large power generation equipment manufacturing groups have greatly improved their production scale and production technology in recent years, which has stimulated the demand for turbine disks for power generation equipment. Significant progress has been made in a new generation of power generation equipment-large ground gas turbines (which can also be used as ship power), which is being domestically developed. The realization of mass production will drive the demand for superalloys. At the same time, the localization of nuclear power equipment will also stimulate the demand for domestic superalloys.

The Development Prospects Of High-Temperature Alloys

1. Research on single crystal blades containing rhenium

In the composition design of single crystals, both alloy performance and process performance should be considered. Since single crystals do not have grain boundaries and are used in harsher environments, certain alloying elements with special effects have been introduced. With the development of single crystal alloys, the chemical composition of alloys has the following changing trends: the introduction of Re elements, the introduction of platinum group elements such as Ru and Ir, and the increase of the content of refractory elements W, Mo, Re, and Ta; the total addition of refractory elements The amount of C, B, Hf and other elements are changed from “complete removal” to “limited use”; the content of Cr is reduced to allow more other alloying elements to be added to maintain the stability of the structure.

The rhenium-containing single crystal blade greatly improves its temperature resistance and creep strength. Compared with the first-generation single crystal alloys represented by PW’s PWA1484, RR’s CMSX-4, and GE’s Rene’N5, the cobalt is appropriately increased by adding 3% rhenium. The content of molybdenum and molybdenum increases its working temperature by 30°C, and its durability and resistance to oxidation and corrosion have reached a good balance.

Single crystal blades containing rhenium are the future trend of aero-engine turbine blades. Because of its temperature resistance, creep strength, thermal fatigue strength, oxidation resistance and corrosion resistance, single crystal blades have been significantly improved compared with directionally solidified columnar alloys, and have quickly been universally recognized by the aviation gas turbine engine community. All advanced aero-engines use single crystal alloys as turbine blades [6].

2. Research on new superalloys

Market analysis New superalloys mainly include four types: powder superalloys, intermetallic compounds, ODS alloys and high-temperature metal self-lubricating materials:

Powder superalloy technology: FGH51 powder superalloy is a phase precipitation strengthened nickel-based superalloy prepared by powder metallurgy. The volume fraction of the γ phase of the alloy is about $,-, and the atomic fraction of its forming elements is about 50%. The manufacturing process of the alloy discs is to use vacuum induction melting to prepare the master alloy, and then atomize to prepare the pre-alloyed powder, and then make the part blank. Compared with similar cast and forged high-temperature alloys, it has the advantages of uniform structure, fine grains, high yield and good fatigue performance. It is a high-temperature alloy with the highest level of strength under the current 650°C working condition. This kind of high temperature gold is mainly used for rotating parts of high-performance engines, such as turbine discs and bearing rings [7].

Intermetallic compounds are used to make components of various advanced vehicle power propulsion systems to reduce dead weight and improve efficiency;

ODS alloy has excellent high-temperature creep performance, high-temperature oxidation resistance, carbon and sulfur corrosion resistance. It can be used to manufacture key components of engines, as well as thermal power generation systems, coal gasifiers, industrial gas turbines and industrial boilers, glass manufacturing, and automobiles. Diesel engines, nuclear reactors, etc.;

High-temperature metal-based self-lubricating materials are mainly used to produce high-temperature self-lubricating bearings, which are mainly used to replace oil-containing bearings, inlaid solid self-lubricating bearings, bimetallic bearings and cast sulfur steel solid lubricating bearings (including cast steel surface vulcanization treatment bearings) in metallurgy Application on equipment, the high temperature self-lubricating bearing has the advantages of high strength, large carrying capacity, good lubrication effect, reasonable structure design, low noise, long service life, etc.