Using Atom Probe Tomography to explore zirconium alloys for nuclear reactors

Understanding irradiation-induced nanoprecipitation in zirconium alloys

Researchers combined three methods of characterisation at different scales to understand the effects of proton irradiation on zirconium alloys commonly used in cladding and structural components of reactor cores.

Iron and Chromium-rich rod-like formations were observed in a Zirconium alloy (Zircaloy-2) following proton irradiation. Correlative analysis in Atom Probe Tomography, electron diffraction and scanning transmission electron microscopy and energy dispersive X-ray (STEM-EDX) revealed the rod morphology, crystallography, dimensions and composition, with good agreement between all three techniques.

Results

Atom Probe Tomography showed that the rods’ Fe/Cr atomic ratio was shown to increase at distances > ~200 nm from the closest partially-dissolved Zr(Fe,Cr)2 SPP, suggesting that the rods nucleate as a result of the irradiation induced dissolution of pre-existing intermetallic phases and that their chemical composition depends on the relative diffusivities of Fe and Cr in the a-Zr matrix.

The research has implications for irradiation-induced growth and hardening in Zirconium alloys, providing a unique insight into the nanoscale irradiation response of these materials, vital to predict future performance and to assist with future alloy design.

The cooperation between Royce Partners (Manchester, Oxford) enables this multi-correlative analysis, utilising equipment from the Royce catalogue that provides chemical and optical characterisation information at different scales.

Click here to read the paper from the Journal of Nuclear Materials November 2018 

Lead contact: Dr Paul Bagot
Royce Partner: University of Oxford 
Collaboration Model: Contract Research