First-principles study of hydrogen diffusion in polycrystalline Nickel

TL;DR

This paper develops a multiscale modeling framework combining first-principles calculations, kinetic Monte Carlo, and finite element methods to predict hydrogen diffusion in polycrystalline nickel, accounting for grain boundaries and trapping effects.

Contribution

It introduces a physically grounded multiscale approach linking atomistic energetics to continuum transport for hydrogen in polycrystalline metals.

Findings

Reproduces experimental trends of hydrogen diffusivity in nickel.

Shows dependence of diffusivity on grain size and boundary type.

Captures trapping and fast-path effects without empirical parameters.

Abstract

Hydrogen embrittlement in metals is strongly governed by hydrogen diffusion and trapping, yet predicting these effects in polycrystalline systems remains challenging. This work introduces a multiscale modeling framework that links atomistic energetics to continuum-scale transport. Migration barriers for bulk and grain-boundary environments, obtained from first-principles calculations, are used in kinetic Monte Carlo simulations to compute anisotropic effective diffusivities. These diffusivities are then incorporated into finite element models of polycrystalline microstructures, explicitly accounting for grain-boundary character and connectivity. The approach captures both fast-path and trapping effects without relying on empirical parameters and reproduces experimental trends for nickel, including the dependence of effective diffusivity on grain size and boundary type. This methodology provides a physically grounded route for predicting hydrogen transport in engineering alloys and can be extended to other materials and defect types.