A Pilot Study on Hydrogen-Mediated Plasticity and Fracture in Nanostructured Metals over Diffusive Timescales

The primary objective of this project is to elucidate the intricate effects of hydrogen on the plasticity and fracture behaviors of metals, specifically focusing on extended diffusive timescales while maintaining an atomistic resolution. Recent studies have underscored the profound influence of hydrogen on the strength and ductility of metals, leading to cracking and catastrophic brittle failures even at stresses below the yield point of susceptible metals. Despite substantial research efforts to comprehend the underlying mechanisms, hydrogen-mediated metal failures remain incompletely understood, particularly when considering the exceedingly long timescales associated with hydrogen diffusion. To address this gap, the central strategy of this project involves the development and validation of a computational tool based on the recently formulated Diffusive Molecular Dynamics (DMD) framework by the principal investigator and collaborators. This initiative will primarily focus on two representative metals: body-centered cubic _-iron and face-centered cubic nickel. The initial phase of the project involves implementing the DMD framework to unveil atomistic details regarding hydrogen distribution in equilibrium and the resultant virial stress on the host metals. Subsequently, the research emphasis will shift towards unraveling the intricate interactions between hydrogen and diverse lattice structures and defects at varying hydrogen chemical potentials and temperatures. The final phase of the project will focus on conducting two simulation tests: uniaxial tension of single-crystal nanowires and nanoindentation of polycrystal nanoplates. These simulations are designed to provide insights into the nanoscale processes that underlie the impact of hydrogen on the strength and ductility of metals over sufficiently extended timescales.