Effects of high niobium addition on the mechanical properties and high-temperature deformability of gamma TiAl alloy

The effects of Nb on the mechanical properties, high-temperature deformability and some other basic properties of TiAl-Nb alloys were investigated over a wide compositional range, and an appropriate composition for high-temperature applications was investigated for both wrought and cast materials. The lattice parameter of Ti-50Al-xNb alloy, which is a gamma single phase alloy, shows an anisotropic variation with Nb content, This lattice distortion is assumed to be responsible for the strengthening and embrittlement of high-Nb ternary alloys. In the case of wrought materials, no appropriate composition exists in the high-Nb content region since wrought materials require good forgeability and high-temperature strength which are properties of antithesis. In the case of cast materials, however, an appropriate composition exists in the vicinity of Ti-46Al-7.5M (at.%). (C) 2002 Elsevier Science Ltd. All rights reserved.