(490c) Theoretical Observations of Hydrogen Trapping and Hydrogen-Induced Failure in Pd-Based Alloys

Super-saturated systems can be formed by exposing metals or metal compounds to high-temperature and high-pressure (high T-P) gas. Superabundant vacancies (SAV) have been discovered in the case of several metals and metal hydrides, which is usually a void defect filled with highly dense gas atoms formed under high T-P conditions. This phenomenon is of particular interest since SAVs exist in the wall material of fusion reactors used to contain high-energy gas (e.g., H and He). It has been known that gas intake in the material wall leads to the formation of blisters and whisker features, which can severely affect reactor performance. Several experimental and theoretical investigations have been done to study the formation and time evolution of SAV structures. Though SAV formation has implications in hydrogen storage potential, they may also reduce susceptibility to hydrogen-induced mechanical failure by trapping and reducing the mobility of H within the material lattice.

This talk presents theoretical insights on hydrogen-trapping and hydrogen-induced mechanical failure in Pd-based alloys. Effect of alloying on material elastic properties, bond strain and electronic structure in Pd systems will be discussed in the context of SAV formation and stabilization. Additionally, trapping and mobility of H will be examined at misfit dislocations at the bulk/hydride interface.