Hydrogen and vacancy clustering in zirconium

Céline Varvenne (1) , Olivier Mackain (1) , Laurent Proville (1) , Emmanuel Clouet (1)

1 SRMP - Service de recherches de métallurgie physique

The effect of solute hydrogen on the stability of vacancy clusters in hexagonal closed packed zirconium is investigated with an ab initioapproach, including contributions of H vibrations. Atomistic simulations within the density functional theory evidence a strong binding of H to small vacancy clusters. The hydrogen effect on large vacancy loops is modeled through its interaction with the stacking faults. A thermodynamic modeling of H segregation on the various faults, relying on ab initiobinding energies, shows that these faults are enriched in H, leading to a decrease of the stacking fault energies. This is consistent with the trapping of H by vacancy loops observed experimentally. The stronger trapping, and thus the stronger stabilization, is obtained for vacancy loops lying in the basal planes, i.e.the loops responsible for the breakaway growth observed under high irradiation dose.

Mots clés: Ab initiocalculations; Vacancies; Stacking faults; Dislocation loops; Zirconium; Hydrogen; Segregation

Domaines: Physique Nucléaire Théorique [nucl-th]; Physique Nucléaire Expérimentale [nucl-ex]

Céline Varvenne, Olivier Mackain, Laurent Proville, Emmanuel Clouet. Hydrogen and vacancy clustering in zirconium. Acta Materialia, 2016, 102, pp.56-69. ⟨10.1016/j.actamat.2015.09.019⟩. ⟨cea-02385740⟩