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Transmission Geometry X-ray Diffraction for Materials Research.

Garrity, D. (2007) Transmission Geometry X-ray Diffraction for Materials Research. Doctoral thesis, University of Surrey (United Kingdom)..

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Abstract

X-ray diffraction is usually thought of as a surface analysis technique. However, given sufficiently energetic X-rays to overcome the inherent attenuation of the sample, this technique may be used for studying the nature of bulk materials. In the work presented here, transmission geometry X-ray diffraction has been further developed for imaging phase transformations and lattice spacing changes in low-alloy ferritic, and austenitic stainless steels under conditions of interest to the Naval Nuclear Propulsion Program (NNPP). A broad account of X-ray diffraction in a transmission geometry is given, detailing the fundamentals of elastic scattering of X-rays including; the classically derived Thomson scatter cross section and the modified Rayleigh scattering cross section for scattering from individual electrons and atoms respectively, and Bragg diffraction that results from scattering of X-rays by ordered, periodic substances. The experimental configurations and apparatus used for energy dispersive and angular dispersive configurations are discussed, and preliminary results for both techniques are presented. Further to this, measurements of both ferritic and austenitic stainless steel are included, the latter involving both static and dynamic measurements of lattice spacing changes induced under an applied tensile load, demonstrating the ability to observe changes as small as 0. 75%. Finally significant work has been carried out with regards to imaging the structural changes brought about by the martensite phase transformation in austenitic stainless steel. In a compressively pre-loaded sample of steel, martensite has been observed at points of high plastic strain by observing the distinct differences in the X-ray diffraction spectra obtained before, and after quenching in liquid nitrogen. This verifies the Finite Element (FE) code used to model these changes, and opens up potential avenues of online-monitoring in the context of the NNPP.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Garrity, D.
Date : 2007
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 2007.
Depositing User : EPrints Services
Date Deposited : 24 Apr 2020 15:27
Last Modified : 24 Apr 2020 15:27
URI: http://epubs.surrey.ac.uk/id/eprint/855233

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