Hydrogen delaying the formation of Guinier-Preston zones in aluminium alloys

The consequences of hydrogen on the formation and growth GP zones during natural ageing in an Al-5Cu alloy is investigated experimentally down to atomic scale numerically using ab initio calculations. As observed through scanning/transmission electron microscopy, hardening kinetic delayed due a slower when incorporated. According calculations, results from trapped vacancies that reduces significantly diffusion coefficient copper self aluminium. This reduction either being path atom exchanges with vacancy (and increasing energy barrier) or dissociated leading less stable state).