In-situ hydrogen charging of zirconium powder to study isothermal percipitation of hydrides and determination of Zr-hydride crystal structure

Zirconium alloys are widely used in the nuclear industry because of their high strength, good corrosion resistance and low neutron absorption cross-section. However, zirconium has strong affinity for hydrogen which leads to hydrogen concentration build-up over time. It is well known that the formation of hydrides will degrade the material and leads to, for example, delayed hydride cracking during high burn up. Even though zirconium hydrides have been studied for several decades, there still remain some controversies regarding the formation mechanisms, exact crystal structure, and stability of various hydride phases. This study uses high resolution synchrotron radiation as a probing tool to observe the precipitation and dissolution of hydrides in highly pure zirconium powder during in-situ hydrogen charging. The experiment enabled the direct observation of the hydride formation and phase transformations. It, also, provided high quality data for crystal structure determination.