Atomic-scale ab initio study of the Zr-H system: II. Interaction of H with plane defects and mechanical properties

The interaction of hydrogen with plane defects (free Surfaces and stacking faults SF) in the alpha-Zr-H solid solution was studied The interaction of hydrogen using ab initio calculations based on density functional theory. A high amount of H strongly lowers Surface excess energies but has little influence on critical cleavage stresses. in contradiction With usual models correlating both quantities. H significantly reduces SF excess energies, thus possibly enhancing planar slip and hindering cross-slip, in agreement with the predictions of the hydrogen-enhanced localised plasticity (HELP) model. (C) 2003 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.