Hydrogen embrittlement of aluminum: the crucial role of vacancies

Phys Rev Lett. 2005 Apr 22;94(15):155501. doi: 10.1103/PhysRevLett.94.155501. Epub 2005 Apr 18.

Abstract

We report first-principles calculations which demonstrate that vacancies can combine with hydrogen impurities in bulk aluminum and play a crucial role in the embrittlement of this prototypical ductile solid. Our studies of hydrogen-induced vacancy superabundant formation and vacancy clusterization in aluminum lead to the conclusion that a large number of H atoms (up to 12) can be trapped at a single vacancy, which overcompensates the energy cost to form the defect. In the presence of trapped H atoms, three nearest-neighbor single vacancies which normally would repel each other, aggregate to form a trivacancy on the slip plane of Al, acting as embryos for microvoids and cracks and resulting in ductile rupture along these planes.