The oxidation resistance of four prototype single crystal nickel-based superalloys for industrial gas turbine applications is studied. All contain greater quantities of Cr than in most existing single crystal superalloys; two are alloyed with Si, one with Re. To explain the results, the factors known to influence the rate of Al(_2)O(_3) scale formation are considered. Models are developed to predict whether any given alloy composition will form a continuous Al(_2)O(_3) scale. These are used to rationalise the dependence of Al(_2)O(_3) scale formation on alloy composition in these systems. The mechanical behaviour of a new single crystal nickel-based superalloy for industrial gas turbine applications is also studied under creep and out-of-phase thermomechanical fatigue (TMF) conditions. Neutron diffraction methods and thermodynamic modelling are used to quantify the variation of the gamma prime ((gamma)’) strengthening phase around the ( gamma)’ solvus temperature; these aid the design of primary ageing heat treatments to develop either uniform or bimodal microstructures of the ( gamma)’ phase. During TMF, localised shear banding occurs with the ( gamma)’ phase penetrated by dislocations; however during creep the dislocation activity is restricted to the matrix phase. The factors controlling TMF resistance are rationalised.
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