Hydrogen trapping and embrittlement susceptibility in Al-Cu-Li alloys

Abstract

The third-generation Al–Cu–Li alloys are found to show little susceptibility to hydrogen embrittlement (HE). Atom probe tomography analysis shows that the primary strengthening precipitate in the alloys, namely T1 (Al2CuLi) phase, is a strong hydrogen trap. The T1 phase is segregated by 1.5 at% of H on average at T6 ageing state. Specially, hydrogen is trapped in the interior of T1 phase so that interfacial decohesion is limited. The presence of T1 phase with high trapping capacity and large number density suppresses the H transport toward the grain boundaries, primarily contributing to the high resistance to HE.