Understanding irradiation assisted hydrogen embrittlement using in situ BCDI.

This proposal describes the use of BCDI at the ID01 beamline to understand the radiation-assisted hydrogen embrittlement (HE) mechanism in Fe and Fe-Cr model single crystals, prepared by dewetting. Three-dimensional coherent X-ray diffraction patterns will be used to image the hydrogen-induced strain, and to quantify the time dependent structural evolution induced during hydrogen charging. These results will be combined with thermal desorption spectroscopy spectra collected ex-situ on a second batch of samples to understand the diffusion mechanisms during hydrogen absorption. In addition, the effect of both hydrogen charging time and irradiation on the defects assisted HE mechanism will be compared between Fe and Fe-Cr crystals. This study will answer the following scientific questions. (i) What is the role of radiation on hydrogen migration during the HE processes? (ii) Do alloying elements such as chromium slow down HE in steel?