Effect of microstructure on the characterization of creep crack growth rate and rupture in TiAl intermetallic alloys

In order to establish a standardised method of creep crack growth testing for creep brittle materials, Round Robin tests and analysis of the results were carried out using a TiAl alloy material tested at 750 deg. C. The TiAl intermetallic contained two different microstructures; one is fully lamellar TiAl and the other fine-grained TiAl. It is found from the results in the Round Robin tests that these materials show creep crack growth different behaviour. In the present study, the characteristics of creep crack growth rate and their rupture lives are considered. It is shown that the characterization of the creep crack growth and the specimen failure lives using the Q* parameter, Larson-Miller parameter and creep ductility criteria are all possible