Tailoring negative pressure by crystal defects: Crack induced hydride formation in Al alloys

TL;DR

This study demonstrates that increasing tensile load at crack tips in Al alloys enhances hydride formation by creating negative pressure regions, with implications for hydrogen storage and corrosion resistance.

Contribution

It introduces a combined simulation and experimental approach to tailor hydride formation in Al alloys through defect engineering and mechanical loading.

Findings

Hydride formation is enhanced at crack tips under tensile stress.

Atom probe tomography confirms increased hydrogen concentration near defects.

Mechanical load influences microstructural hydrogen trapping.

Abstract

Climate change motivates the search for non-carbon-emitting energy generation and storage solutions. Metal hydrides show promising characteristics for this purpose. They can be further stabilized by tailoring the negative pressure of microstructural and structural defects. Using systematic ab initio and atomistic simulations, we demonstrate that an enhancement in the formation of hydrides at the negatively pressurized crack tip region is feasible by increasing the mechanical tensile load on the specimen. The theoretical predictions have been used to reassess and interpret atom probe tomography experiments for a high-strength 7XXX-aluminium alloy that show a substantial enhancement of hydrogen concentration at structural defects near a stress-corrosion crack tip. These results contain important implications for enhancing the capability of metals as H-storage materials.