Developing high Co-containing Ni-based superalloys with improved oxidation behaviour for future jet-engine applications

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Ni-based superalloys are the alloys of choice for high performance, critical components used at the high temperature sections of gas turbines. In order to enable continuous efficiency gains, gas turbine manufacturers seek to push the operating conditions of Ni-based superalloys to ever higher temperatures and stresses. As a result, the environmental resistance of superalloys is increasingly becoming of critical importance as the elevated temperatures of future engines drives the components into harsher operating regimes. Consequently, the focus of future alloy design programs has identified environmental resistance as a key property for optimisation. Previous research has shown that Ni-based superalloys with elevated Co concentrations possess properties capable of achieving the stringent operating requirements of newer generations of jet engines. In particular, the environmental resistance of such alloys, has been shown to outperform current state-of-the-art superalloys. This behaviour has been demonstrated despite reduced Cr and increased Ti concentrations, which have traditionally been markers of poor oxidation behaviour. In close collaboration with Rolls-Royce plc, this project will focus on establishing the mechanisms that govern the oxidation behaviour in these materials and to inform future alloy design strategies for improved environmental resistance. This will be achieved through a comprehensive experimental matrix that will seek to firstly develop an in-house method of material manufacture, followed by oxidation trials and extensive characterisation utilising thermal analysis, microscopy and advanced diffraction techniques at national facilities. The project will also seek to identify the effects of pre-existing oxidation damage on the overall mechanical properties of the alloys. In parallel, thermodynamic and kinetic modelling approaches will be evaluated against experimental data and the models will be further informed and improved to account for alloys with elevated Co-concentrations. Consequently, the data generated through this project will provide Rolls-Royce with invaluable insights into current alloy behaviour and will inform future alloy development programs.