Stability of β″ nano-phases in Al-Mg-Si(-Cu) alloy under high dose ion irradiation

Camille Flament (1) , Joël Ribis (1) , Jérôme Garnier (1) , Yves Serruys (1) , F. Leprêtre (1) , Aurélie Gentils (2) , C. Baumier (2) , M. Descoins (3) , Dominique Mangelinck (3) , A. Lopez (1) , Kimberly Colas (4) , Karl Buchanan (1) , Patricia Donnadieu (5) , Alexis Deschamps (5)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 CSNSM - Centre de Sciences Nucléaires et de Sciences de la Matière
3 IM2NP - Institut des Matériaux, de Microélectronique et des Nanosciences de Provence
4 SPC - Service de Physico-Chimie
5 SIMaP - Science et Ingénierie des Matériaux et Procédés

The microstructure of a 6061-T6 Al alloy subjected to ion irradiation at 95 and 165 displacements per atom (dpa) has been evaluated by transmission electron microscopy and atom-probe tomography. The initial microstructure of the alloy is dominated by needle-shaped β″ precipitates. After 95 dpa irradiation, the β″ precipitates display a slight lattice distortion and are partially dissolved, together with the formation of a new phase. After 165 dpa irradiation, the β″ precipitates are completely dissolved, the new phase has grown and a high density of clusters rich in Mg, Si, Cu and Cr is observed. The determination of ballistic versus radiation enhanced diffusion coefficients shows that enhanced diffusion is predominant for β” dissolution. The formation and growth of the new particles may be caused by radiation induced segregation. Solute drag by vacancies or mixed dumbbell interstitials migration could explain the diffusion of some elements as Si or Cr towards the new particles.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

Camille Flament, Joël Ribis, Jérôme Garnier, Yves Serruys, F. Leprêtre, et al.. Stability of β″ nano-phases in Al-Mg-Si(-Cu) alloy under high dose ion irradiation. Acta Materialia, 2017, 128, pp.64-76. ⟨10.1016/j.actamat.2017.01.044⟩. ⟨hal-01555155⟩