First principle calculations of the interaction of hydrogen with other defects in Ni and study of the dynamical and thermodynamical process by means of a classical approach – EcHyDNA

The context of the project is the damaging of metallic alloys in their environment. We want to predict, on the long term, the loss of mechanical properties of structural materials (nickel based alloys, steels and aluminum alloys) due to Stress Corrosion Cracking (SCC) and hydrogen embrittlement. The goal is to enhance applications’ safety (air plane, civilian nuclear plants, pipelines...) and to reduce maintenance costs.
The project consist in the development of a multi-scale simulation (coupling first principle calculations –DFT- and classical modeling of diffusion processes via Molecular Dynamics and Monte Carlo) of some key mechanisms involved in hydrogen embrittlement. We will focus on the interactions between hydrogen and crystalline defects in nickel (vacancies clusters and self-interstitials) and on the influence of hydrogen on vacancies diffusion (kinetics). This theoretical project is part of a larger collaboration with an experimental group (J. Chêne CEA) which works on the formation of hydrogen -vacancy clusters in single crystals and intergranular segregation in ultra pure nickel polycristals. Oxidation kinetics will be studied on a model alloy with industrial characteristics.
We will use first principle calculations based on the density functional theory (DFT) to study the different interactions between hydrogen and vacancies. In parallel, a classical study of trapping/detrapping mechanisms will be done to calculate the apparent diffusion coefficient of the vacancies.
We hope, through this original approach, to be able to analyze and predict microscopic effects at the origin of the SCC.