Research progress of nickel-based superalloy materials
Over the past half century, China has developed and formed many nickel-based superalloy systems to meet the growing needs of power, transportation, aviation, aerospace and other industries. In particular, the development of nickel-based superalloys has greatly improved the performance of China's aerospace engines. made a significant contribution to improvement. This paper briefly introduces the development history of nickel-based superalloys, reviews the research progress of nickel-based superalloys in recent years, and discusses the application and development trends of nickel-based superalloys.
introduction
More than 50% of the materials in modern gas turbine engines use high-temperature alloys, of which the amount of nickel-based high-temperature alloys accounts for about 40% of the engine materials. Nickel-based alloys have excellent comprehensive properties at medium and high temperatures. They are suitable for working at high temperatures for a long time and can resist corrosion and abrasion. They are the most complex and widely used in high-temperature parts and have many metallurgical properties among all superalloys. Alloys of greatest interest to workers. Nickel-based high-temperature alloys are mainly used in structural components working at 950~1050°C in the aerospace field, such as aeroengine working blades, turbine disks, combustion chambers, etc. Therefore, the study of nickel-based superalloys is of great significance to the development of my country's aerospace industry.
1 Overview
Nickel-based high-temperature alloys are high-temperature alloys that use nickel as the matrix (generally more than 50% content) and have high strength and good resistance to oxidation and gas corrosion in the range of 650 to 1000°C. It is developed on the basis of Cr20Ni80 alloy. In order to meet the requirements of high-temperature thermal strength (high-temperature strength, creep resistance, high-temperature fatigue strength) around 1000°C and anti-oxidation and anti-corrosion in gas media, a large number of reinforcements have been added. Elements, such as W, Mo, Ti, Al, Nb, Co, etc., to ensure its superior high temperature performance. In addition to solid solution strengthening, superalloys also rely on the precipitation strengthening of the intermetallic compound γ′ phase (Ni3Al or Ni3Ti, etc.) formed by Al, Ti, etc. and Ni, the intragranular dispersion strengthening of some fine stable MC, M23C6 carbides, and B, Zr, Re, etc. play a role in purifying and strengthening grain boundaries. The purpose of adding Cr is to further improve the anti-oxidation and high-temperature corrosion resistance of high-temperature alloys. Nickel-based superalloys have good comprehensive properties and have been widely used in the aerospace, automotive, communications and electronics industry sectors. With the exploration of the potential properties of nickel-based alloys, researchers have put forward higher requirements for their performance. Domestic and foreign scholars have developed new processing techniques for nickel-based alloys, such as isothermal forging, extrusion deformation, cladding deformation, etc. .
2. Development history of nickel-based superalloys
Nickel-based superalloys occupy a particularly important position in the entire field of superalloys. Its development and use began in the late 1930s, and were developed against the background that the emergence of jet aircraft put higher requirements on the performance of superalloys. . The United Kingdom first produced the nickel-based alloy Nimonic75 (Ni-20Cr-0.4Ti) in 1941. In order to improve the creep strength, aluminum was added to develop Nimonic80 (Ni-20Cr-2.5Ti-1.3Al). The United States in the mid-1940s, the Soviet Union in the late 1940s, and China in the mid-1950s also developed nickel-based superalloys.
The development of nickel-based high-temperature alloys includes two aspects: improvement of alloy composition and innovation of production processes. In the early 1950s, the development of vacuum smelting technology created conditions for refining nickel-based alloys containing high aluminum and titanium; in the late 1950s, investment precision casting technology was used to develop a series of casting alloys with good high-temperature strength; in the 1960s In the mid-term, directional crystallization and single crystal superalloys and powder metallurgy superalloys with better performance were developed; in order to meet the needs of ships and industrial gas turbines, a number of high-chromium nickel-based high-chromium nickel-based alloys with better hot corrosion resistance and stable structure were developed since the 1960s. alloy. In about 40 years from the early 1940s to the late 1970s, the operating temperature of nickel-based alloys increased from 700°C to 1100°C, with an average increase of about 10°C per year.
