Gamma titanium aluminide (gamma-TiAl) is a material essential to meeting military and civil engine performance targets and potentially could be used throughout the engine from compressor to combustor to turbine to exhaust. The established Rools-Royce alloy is the Howmet proprietary alloy, Ti-45-2-2-XD, which competes for lower temperature applications such as compresor stators and structural comonents by taing advantages of the lower costs arising from the casting route. However, the delayed introduction of gamma-TiAl into the aero-engine and the extension of the Rolls-Royce family to include Allison and BRR has provided a unique opportunity to assess the mechanical properties and costs of a wider range of developed alloys. The technical basis for this evalaution will be discussed with an emphasis on the selection of a ubiquitous high strength alloy with high temperature capability and minimised production costs.
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