The dislocation-core properties of Al, with and without H impurities, were studied by using the Peierls-Nabarro model; with the parameters being deduced from ab initio calculations. It was found that H not only facilitated dislocation emission from crack tips, but also markedly enhanced dislocation mobility and led to macroscopic softening and thinning of the material ahead of the crack tip. A strong binding was observed between the H and the dislocation cores, with the binding energy depending upon the nature of the dislocation. This dependence could directly affect the mechanical properties of Al by inhibiting dislocation cross-slip and promoting slip planarity.

Hydrogen-Enhanced Local Plasticity in Aluminium - An Ab Initio Study. G.Lu, Q.Zhang, N.Kioussis, E.Kaxiras: Physical Review Letters, 2001, 87[9], 095501 (3pp)