First-principles study of the interstitial stability and microscopic diffusion mechanism of hydrogen atom in Zr, Ti elemental and ZrTi2 alloys

Abstract

Hydrogen absorbing materials based on titanium with high hydrogen absorbing capacity such as Ti–Mo, Ti–Zr–V, Ti–Zr and so on have gained significant attention in recent years. It's necessary to optimize and improve the properties of structural materials for studying the behavior of hydrogen impurities in zirconium-titanium alloys. In order to discuss whether hydrogen atoms can stably exist in the interstitial space of Ti–Zr alloy and find the optimal diffusion path of hydrogen atoms in Ti–Zr alloy, we study the hydrogen atom diffusion ability and migration path in Ti–Zr alloy and the change of the formation energy of hydrogen atom at the interstitial defect based on First principles in this paper. Through calculations, it can be concluded that hydrogen atoms tend to occupy the tetrahedral gaps containing only Ti atoms. Furthermore, it's easiest for hydrogen atoms to diffuse between the gaps of the Zr–Zr layer and the best diffusion path for hydrogen atoms in the Ti–Zr alloy is also in the Zr–Zr layer. In general, it's easy for hydrogen atoms to migrate near Zr atoms. The energy expansion barrier of hydrogen atoms between adjacent gaps will be affected by the first neighboring metal atoms, and the first neighboring metal atoms have an inhibitory effect on the diffusion of hydrogen atoms. By comparing the diffusion of hydrogen atoms in Zr, Ti and Zr–Ti alloys, it has been found that the diffusion rate of hydrogen atoms in Zr–Ti alloys is greater than that in Zr and Ti. The above results will provide a theoretical reference for further exploring the microscopic mechanism of hydrogen diffusion in zirconium-titanium alloys.