High temperature structural materials, such as nickel-based superalloys, have contributed immensely to societal benefit. These materials provide the backbone for many applications within key industries that include chemical and metallurgical processing, oil and gas extraction and refining, energy generation, and aerospace propulsion. Within this broad application space, the best known challenges tackled by these materials have arisen from the demand for large, efficient land-based power turbines and light-weight, highly durable aeronautical jet engines. So impressive has the success of these materials been that some have described the last half of the 20 th century as the Superalloy Age. Many challenges, technical and otherwise, were overcome to achieve successful applications. This paper highlights some of the key developments in nickel superalloy technology, principally from the perspective of aeronautical applications. In the past, it was not unusual for development programs to stretch out 10 to 20 years as the materials technology was developed, followed by the development of engineering practice, and lengthy production scaleup. And many developments fell by the wayside. Today, there continue to be many demands for improved high temperature materials. New classes of materials, such as intermetallics and ceramic materials, are challenging superalloys for key applications, given the conventional wisdom that superalloys are reaching their natural entitlement level. Therefore, multiple driving forces are converging that motivate improvements in the superalloy development process. This paper concludes with a description of a new development paradigm that emphasizes creativity, development speed, and customer value that can provide superalloys that meet new needs.
IntroductionThe modern world has made great use of high strength structural materials to design facilities and equipment that we cannot live without. Structural materials are the backbone of any mechanical system since they must support the loads and endure the degradation modes of the operating environment. The critical roles played by materials that reliably serve under difficult conditions is impressive. For example, electric generating plants, oil refineries, chemical processing plants, industrial furnaces, and aircraft engines all depend on nickel-based superalloys. Our industrial age could hardly exist without the capabilities enabled by these materials. But the public is generally not aware of these materials since they are specialized and oftentimes are not directly observed.The aviation industry, with its current fleet of airplanes powered by fast, fuel efficient, quiet engines, would not be possible without superalloys. Jet engines are particularly challenging for structural materials since the operating environment is hot, loads are high to minimize weight, stiffness is crucial to maintain clearances throughout the operating envelope, critical structural components are buried deep within the engine and not easily accessible for inspe...
