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Nickel-Based Superalloys for Advanced Turbine Engines: Chemistry, Microstructure and Properties

2006; American Institute of Aeronautics and Astronautics; Volume: 22; Issue: 2 Linguagem: Inglês

10.2514/1.18239

1533-3876

Tresa M. Pollock, Sammy Tin,

High-Temperature Coating Behaviors

The chemical, physical, and mechanical characteristics of nickel-based superalloys are reviewed with emphasis on the use of this class of materials within turbine engines.The role of major and minor alloying additions in multicomponent commercial cast and wrought superalloys is discussed.Microstructural stability and phases observed during processing and in subsequent elevated-temperature service are summarized.Processing paths and recent advances in processing are addressed.Mechanical properties and deformation mechanisms are reviewed, including tensile properties, creep, fatigue, and cyclic crack growth. I. IntroductionN ICKEL-BASED superalloys are an unusual class of metal- lic materials with an exceptional combination of hightemperature strength, toughness, and resistance to degradation in corrosive or oxidizing environments.These materials are widely used in aircraft and power-generation turbines, rocket engines, and other challenging environments, including nuclear power and chemical processing plants.Intensive alloy and process development activities during the past few decades have resulted in alloys that can tolerate average temperatures of 1050 • C with occasional excursions (or local hot spots near airfoil tips) to temperatures as high as 1200 • C, 1 which is approximately 90% of the melting point of the material.The underlying aspects of microstructure and composition that result in these exceptional properties are briefly reviewed here.Major classes of superalloys that are utilized in gas-turbine engines and the corresponding processes for their production are outlined along with characteristic mechanical and physical properties. II. Superalloys in Gas-Turbine EnginesNickel-based superalloys typically constitute 40-50% of the total weight of an aircraft engine and are used most extensively in the combustor and turbine sections of the engine where elevated temperatures are maintained during operation. 1Creep-resistant turbine blades and vanes are typically fabricated by complex investment casting procedures that are essential for introduction of elaborate cooling schemes and for control of grain structure.Such components may contain equiaxed grains or columnar grains, or may be