Microstructural evolution in power plant materials

Materials that are commonly used in steam and gas power plant are exposed to high stresses and high temperatures over prolonged durations. As a result of this, the microstructures evolve owing to changes in the precipitate distribution from diffusional changes and changes in the grain structure and morphology. Our work in this area is investigating microstructural evolution in 9-12%Cr steels, particularly E911 and a range of experimental cast materials, and microstructural evolution in weldments (in collaboration with Professor Vlastimil Vodarek, Vitkovice - Research and Development, Ltd., Ostrava, Czech Republic). We are also working on microstructural evolution in Ni-based superalloys such as Inconel 617 and 625 and Nimonic 263. The work combines a mixture of advanced microscopy using high resolution scanning electron microscopy and transmission electron microscopy and microstructural modelling.


A transmission electron microscope micrograph of precipitates in E911	A field emission gun scanning electron microscope image of a martensitic microstructure

An electron backscatted diffraction image of the grain structure in a martensitic steel. The different colours represent areas of different crystallographic orientations.	A backscattered electron image of precipitates in a sample of creep exposed IN617 alloy. The precipitates of differing contrast can be investigated by energy dispersive X-ray analysis to determine the chemical composition and this can be related to microstructural models of precipitate evolution in these alloys.

Author: Sarah Hainsworth, last updated 25/9/2008.

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