An analysis of small punch creep behaviour in the γ titanium aluminide Ti–45Al–2Mn–2Nb

Previous literature on gamma titanium alumindes (γ-TiAl) have found that this family of alloys offer significant potential for replacing more conventional nickel and titanium based alloy systems in future designs of gas turbine engines. Despite the inherent brittle nature of such materials, γ-TiAl typically exhibits considerable ductility at elevated temperatures and a demonstrable uniaxial creep response. Until now, the creep properties of γ-TiAl have primarily been sourced from conventional uniaxial approaches, which require significant material quantities in order to perform a full stress–temperature–life assessment. This is not always possible for new alloys where sufficient quantities of material are unavailable. The small punch (SP) creep test represents an attractive alternative to uniaxial creep testing since the volume of material required is much less. However, much of the current literature on SP testing is limited to the application of traditionally ductile materials. This paper assesses the suitability of the SP method to characterise the creep properties of γ-TiAl alloys. Finite element modelling has been used to characterise the SP deformation and rupture behaviour.