81 Influence of Hydrogen on the Cohesive Energies of Al/Si and Al/Mg₂Si Interfaces

Estimation of hydrogen effects on lattice defects and strength of interfaces is important for understanding hydrogen embrittlement mechanisms and accurately evaluating the strength of materials in a hydrogen environment. In this study, we estimated the hydrogen-trap energies of Al/Si and Al/Mg₂Si interfaces that are important for 6000-series aluminum alloys and calculated their cohesive energies under a practical hydrogen concentration by first-principles calculations. The hydrogen-trap energy of Al/Si interface is much stronger than various lattice defects in Al and the Al/Mg₂Si interface. If we assume a nominal hydrogen concentration of 1.61 ppm at 300 K, the hydrogen occupancy at trap sites in the Al/Si interface ranges from 0.38 to 1.00, and its cohesive energy is significantly reduced.