Corrosion mechanism of a Ni-based alloy in supercritical water: Impact of surface plastic deformation

Mickaël Payet (1, 2) , Loic Marchetti (3, 1) , Michel Tabarant (4, 1) , Jean-Pierre Chevalier (2, 5)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 CNAM - Conservatoire National des Arts et Métiers [CNAM]
3 CEA - Commissariat à l'énergie atomique et aux énergies alternatives
4 SEARS - Service d'études analytiques et de réactivité des surfaces
5 PIMM - Laboratoire Procédés et Ingénierie en Mécanique et Matériaux

Ni–Fe–Cr alloys are expected to be a candidate material for the generation IV nuclear reactors that use supercritical water at temperatures up to 600 °C and pressures of 25 MPa. The corrosion resistance of Alloy 690 in these extreme conditions was studied considering the surface finish of the alloy. The oxide scale could suffer from dissolution or from internal oxidation. The presence of a work-hardened zone reveals the competition between the selective oxidation of chromium with respect to the oxidation of nickel and iron. Finally, corrosion mechanisms for Ni based alloys are proposed considering the effects of plastically deformed surfaces and the dissolution.

Mots clés: Intergranular corrosion; High temperature corrosion; Selective oxidation; Internal oxidation; Nickel alloy

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

Mickaël Payet, Loic Marchetti, Michel Tabarant, Jean-Pierre Chevalier. Corrosion mechanism of a Ni-based alloy in supercritical water: Impact of surface plastic deformation. Corrosion Science, 2015, 100, pp.47-56. ⟨10.1016/j.corsci.2015.06.032⟩. ⟨cea-02389721⟩