Microstructural evolution of Q12$^{TM}$ alloy irradiated in PWR and comparison with other Zr base alloys

S. Doriot (1) , B. Verhaeghe (1) , A. Soniak-Defresne (1) , T. Lejolu (1) , P. Bossis (1) , D. Gilbon (1) , V. Chabretou (2) , J-P. Mardon (2) , M. Ton-That (3) , A. Ambard (4)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 AREVA
3 EDF DPN/DIN - EDF Division Production Nucléaire/Division Ingénierie Nucléaire
4 EDF R&D - EDF R&D

Based on the M5® alloy metallurgy, the Q12™ alloy (Zr-1Nb-0.5Sn-0.1Fe) was developed by AREVA NP for structural components, with ultra-low Sn addition and slightly increased Fe content. The behavior of this alloy was tested under irradiation in PWR and has shown, in comparison to M5®, improvement in irradiation creep strength and similar free growth. The present paper provides results on dimensional stability and details the microstructural evolution of Q12™ alloy under neutron irradiation in PWR. The microstructural evolution under irradiation of Q12™ was studied for fast neutron fluences up to 13x10$^{25}$ n/m$^2$ (E>1 MeV) with Analytical Transmission Electron Microscopy observations, focused on radiation-enhanced needle-like particles, Laves Phases, and linear density of -component loops. These results are compared with other quaternary Zr-Nb-SnFe alloys and with M5®. All these results allow a general discussion about microstructural evolution and behavior under irradiation of quaternary type alloys compared to M5® alloy. This study, in agreement with previous works on Zr1Nb and quaternary alloys, seems to show that increasing the iron content with the presence of niobium and tin will decrease the - component loop linear density and delay the growth breakaway

Keywords: Zr-alloys; quaternary alloys; <c>-component loops; radiation-enhanced precipitation; growth; Laves phases; irradiation 2

Domains: Nuclear Experiment [nucl-ex]; Nuclear Theory [nucl-th]

S. Doriot, B. Verhaeghe, A. Soniak-Defresne, T. Lejolu, P. Bossis, et al.. Microstructural evolution of Q12$^{TM}$ alloy irradiated in PWR and comparison with other Zr base alloys. ASTM B10 - 18th International Symposium on "Zirconium in the Nuclear Industry, May 2016, Hilton Head, United States. pp.823-856, ⟨10.1520/STP159720160061⟩. ⟨cea-02500848⟩