Brief Analysis on The Application And Development Trend of Nickel-based High-temperature Alloy Materials

Nickel-based high-temperature alloy is a high-temperature alloy with nickel as the matrix (content is generally greater than 50%), which has high strength and good oxidation resistance and gas corrosion resistance in the range of 650~1000℃. 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) at about 1000℃ and oxidation resistance and corrosion resistance in gas medium, a large number of strengthening elements such as W, Mo, Ti, Al, Nb, Co, etc. are added to ensure its superior high-temperature performance.

In addition to the solid solution strengthening effect, the high-temperature alloy relies more on the precipitation strengthening of the intermetallic compound γ′ phase (Ni3Al or Ni3Ti, etc.) formed by Al, Ti, etc. and Ni, and the intragranular dispersion strengthening of some small stable MC, M23C6 carbides, as well as the purification and strengthening of B, Zr, Re, etc. on the grain boundaries. The purpose of adding Cr is to further improve the oxidation resistance and high-temperature corrosion resistance of the high-temperature alloy.

Nickel-based high-temperature alloy has good comprehensive properties and has been widely used in aerospace, automobile, communication and electronic industries. With the exploration of the potential performance of nickel-based alloys, researchers have put forward higher requirements on their performance. Domestic and foreign scholars have developed new processing technologies for nickel-based alloys, such as isothermal forging, extrusion deformation, and sheath deformation.

Application of Nickel-Based Superalloys

In aerospace engines, the working conditions are high temperatures of 600~1200℃, the stress effects are complex, and the requirements for materials are stringent; nickel-based high-temperature alloys have sufficiently high heat resistance, good plasticity, resistance to high-temperature oxidation and gas corrosion, and long-term organizational stability. Therefore, nickel-based high-temperature alloys are mainly used to manufacture hot end components of turbine engines and various high-temperature components of aerospace rocket engines.

In aviation turbine engines, nickel-based high-temperature alloys are mainly used in combustion chambers, guide vanes, turbine blades and turbine disks; in aerospace rocket engines, they are mainly used in turbine disks, in addition to engine shafts, combustion chamber partitions, turbine inlet ducts and sprinklers.

With the development of my country's industrialization, nickel-based high-temperature alloys are gradually being used in civil industry's energy and power, transportation, petrochemical, metallurgy, mining, glass and building materials sectors. At present, nickel-based high-temperature alloys are mainly used in diesel engines and internal combustion engine turbochargers, industrial gas turbines, internal combustion engine valve seats, steering rollers, etc.

Development Trend of Nickel-Based Superalloys

From the perspective of use and development, the development trend of nickel-based high-temperature alloys must be towards high strength, thermal corrosion resistance, and low density.

(1) Pursuit of high strength. By adding appropriate amounts of Al, Ti, and Ta, the amount of γ′ strengthening phase is guaranteed; adding a large amount of refractory metal elements such as W, Mo, and Re is also an effective way to improve strength. However, in order to maintain good structural stability and not precipitate harmful phases such as σ and μ, the structural stability of the alloy is improved by adding Ru in the new generation of alloys.

(2) Develop single crystal alloys with excellent thermal corrosion resistance. By adding appropriate amounts of refractory metals such as W and Ta, a high Cr content is guaranteed.

(3) Develop single crystal alloys with low density. From the perspective of aircraft engine design, alloys with high density are difficult to achieve, especially for moving blades, which are not suitable under very large centrifugal forces. To this end, it is necessary to develop single crystal high-temperature alloys with low density, such as CMSX-6, RR2000, TMS-61, AM-3, ONERAM-3, etc. Among them, the RR2000 single crystal alloy is actually developed on the basis of IN100 (K17) alloy, with a density of 7.87g/cm3.