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# Nickel-based single crystal superalloys for industrial gas turbines

Sato, Atsushi (2012)
Ph.D. thesis, University of Birmingham.

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## Abstract

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.

Type of Work: Ph.D. thesis. Reed , Roger C. and Green, Nick and Evans, Hugh Colleges (2008 onwards) > College of Engineering & Physical Sciences Department of Metallurgy and Materials T Technology (General)TA Engineering (General). Civil engineering (General)TN Mining engineering. MetallurgyTS Manufactures University of Birmingham 3533
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