I focus on the use of synchrotron and neutron diffraction to examine important materials and engineering questions. I previously worked at the European Synchrotron Radiation Facility and my research has continued to exploit the ability of this unique form of radiation to examine how materials behave when you heat and deform them. My work can be broadly seperated into two areas: the determination of stresses in manufactured components and the examination of phase transformations in novel materials. The first catagory includes stresses in friction stir welds and large diameter pipe welds while the second includes stress induced transformations of zirconium hydrides and deformation structures in titanium aluminides.