ABSTRACT
New high-temperature creep-resistant materials are in demand for three main purposes: land-based engines, engines for aircraft operating at subsonic or moderate supersonic speeds, and engines and airframes for hypersonic aircraft operating above Mach 3 or 4, where new aerodynamic features may appear. The chapter discusses the various classes of alloy which are believed to show promise, and provides a brief account of the theoretical design of alloys. It considers alloys having the same L12 structure as the superalloys, then B2 structures similar to β brass, and other ordered alloy structures. The chapter briefly describes ceramics, two-phase and three-phase structures, and nanocrystals. High-temperature creep-resistant alloys are likely to be based on structures of high elastic modulus and high melting point. A high-temperature creep-resistant alloy must have a low creep rate at high temperatures and high stresses. Most potential high-temperature creep-resistant materials are unsuitable for practical use because they are brittle at room temperature.
