Mr Inigo Stratton

Gas turbines are an established technology, which despite the move towards more renewable energy, still dominate the power generation sector. As heat engines, they can be thermodynamically modelled using a Carnot cycle, and thus their efficiency increases with operating temperature. This efficiency is limited by the capabilities of the material used to fabricate the components in the hottest sections. Currently, Ni-based superalloys are the ubiquitous choice for such applications, but they are reaching their physical limits.  Refractory metal based superalloys (RSAs) are a developing class of materials that can maintain exceptional strength at higher temperatures than Ni-based superalloys. The source of their strength lies in their fine scale microstructure, which consists of disordered body-centred cubic precipitates (A2) within an ordered superlattice (B2) matrix phase.  However, these alloys exhibit poor oxidation resistance, with many exemplar alloys lasting less than 24 hours before structural failure. Recent research has identified the potential of the high temperature oxide CrTaO4 to form a protective layer, providing a new avenue for alloy development. This research aims to develop a new high temperature RSA based on the Cr-Ta-Ti system.  The work will establish the extent of the compositional region where the CrTaO4 oxide can form and explore how it is influenced through higher order alloying.  The work will also investigate the microstructural evolution of this system with an aim to understand how alloying can lead to the development of the desired two-phase combination of A2-B2 and the influence this has on mechanical performance. Integration of these activities will guide assessments of the multicomponent alloy space and define compositions that can produce oxidation resistant RSAs.