Interfacial properties of hydrides in α-Zr: a theoretical study

In order to better understand hydride formation in zirconium alloys, heterophase interfaces between α-Zr and γ-ZrH are investigated by means of ab initio atomic-scale simulations of multilayers coupled with continuous elasticity. Our approach allows us to separate out the elastic contribution, leading to basal and prismatic [Formula: see text] interface energies around 200 [Formula: see text] and 750 [Formula: see text] respectively, i.e. values noticeably higher than previously found for coherent particles such as ζ-Zr₂H. By considering interfacial changes of H contents, the possibility of competing elasticity and chemistry effects for interface stability is analyzed. The effects of the strong anisotropy evident in [Formula: see text] interface energies on the important practical issue of preferential habit planes are discussed, allowing us to propose a plausible explanation for the experimental results.