Gamma titanium aluminides as prospective structural materials

This status report focuses on specific products of two gamma -TiAl alloys that are advancing toward structural applications for 550-750 degreesC service in advanced turbine engines. These are low-pressure turbine blade, transition-duct beam and radial diffuser castings for engine components, and corner-beam and closeout beam castings for the outlet-nozzle of a very large engine. Also included are current development of sheet corrugations for formed subcomponents and the perfection of cast turbine wheels for automotive turbochargers. In the current implementation stage, alloy composition, desired process and component definition are the important introductory issues. Then, the engineering technology that must be developed is discussed for the desired final product and a match of cost and benefit. Balancing better performance with the acceptance constraints is the key. Cost is a major constraint along with real and perceived risk. Within five to ten years, systematic reduction of certain hardware costs will occur as familiarity builds and enters into the production stage. (C) 2000 Elsevier Science Ltd. All rights reserved.