Predictive Model of Hydrogen Trapping and Bubbling in Nanovoids in BCC Metals

TL;DR

This study develops a predictive model for hydrogen trapping and bubbling in nanovoids of BCC metals, specifically tungsten, providing new insights into hydrogen-induced damage mechanisms in structural materials.

Contribution

The paper introduces the first explicit model for hydrogen behavior in nanovoids of BCC metals, combining adsorption energetics with multiscale simulations and experimental validation.

Findings

Hydrogen adatoms sequentially adsorb on nanovoid surfaces with distinct energy levels.

Hydrogen adatom interactions are dominated by pairwise power law repulsion.

The model accurately predicts hydrogen molecule formation and trapping in nanovoids.

Abstract

Interplay between hydrogen and nanovoids, despite long-recognized as a central aspect in hydrogen-induced damages in structural materials, remains poorly understood. Focusing on tungsten as a model BCC system, the present study, for the first time, explicitly demonstrated sequential adsorption of hydrogen adatoms on Wigner-Seitz squares of nanovoids with distinct energy levels. Interaction between hydrogen adatoms on the nanovoid surface is shown to be dominated by pairwise power law repulsion. A predictive model was established for quantitative prediction of configurations and energetics of hydrogen adatoms in nanovoids. This model, further combined with equation of states of hydrogen gas, enables prediction of hydrogen molecule formation in nanovoids. Multiscale simulations based on the predictive model were performed, showing excellent agreement with experiments. This work clarifies fundamental physics and provides full-scale predictive model for hydrogen trapping and bubbling in nanovoids, offering long-sought mechanistic insights crucial for understanding hydrogen-induced damages in structural materials.