Degree Type

Dissertation

Date of Award

2008

Degree Name

Doctor of Philosophy

Department

Physics and Astronomy

First Advisor

Joseph Gray

Second Advisor

David Vaknin

Abstract

A nondestructive high energy (60 keV) x-ray diffraction method to measure the internal strain depth-profile in materials was developed using a standard 320 kVp laboratory x-ray source. Traditional x-ray strain measurements are limited to few microns of depth due to the limited penetration of Cu Ka and Mo Ka radiation if a synchrotron or neutron source is not used. The high energy used allows for greater penetration without a synchrotron or neutron facility. Results for aluminum with penetration depths of 1mm and for titanium with penetration depths of 300 micrometers are demonstrated. The spatial resolution of this depth-profile is 50 micrometers to 125 micrometers depending on the collimation and attenuation of the sample. Sensitivity to a lattice parameter change of 0.001A is demonstrated. An energy dispersive HPGe detector is used to perform fixed-angle diffraction measurements. The strain depth-profile measurement is performed by observing the change in the position of the diffraction peaks in the energy dispersive spectrum. A simulation program of the diffraction system for modeling and validating the experimental setup is developed. A new technique to measure the strain using the natural width of the tungsten Ka1 line and the diffraction peak normalized intensity is presented. The results of the energy dispersive technique and the tungsten Ka1 line width technique are compared to the results obtained using high energy angle dispersive XRD technique. Finally we present a preliminary study of the thermal relaxation of residual stress.

DOI

https://doi.org/10.31274/etd-180810-2483

Copyright Owner

Mohammad Yousef Al-shorman

Language

en

Date Available

2012-04-30

File Format

application/pdf

File Size

286 pages

Included in

Physics Commons

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