Iron redistribution in a zirconium alloy after neutron and proton irradiation studied by energy-dispersive X-ray spectroscopy (EDX) using an aberration-corrected (scanning) transmission electron microscope

Zirconium alloys used as cladding materials in nuclear reactors can exhibit accelerated irradiation induced growth, often termed linear growth, after sustained neutron irradiation. This phenomenon has been linked to the formation of <c>-component dislocation loops and to the concentration of interstitial solute atoms. It is well documented for the Zircaloys that Fe dissolves from second phase particles (SPPs) during irradiation thus increasing the interstitial solute concentration in the matrix. However, no progress has yet been made into understanding whether a similar process occurs for the newer ZIRLO™ alloys. We aim to overcome this shortcoming here by studying compositional changes in second phase particles in Low Tin ZIRLO™ after neutron and proton irradiation using energy dispersive X-ray (EDX) spectroscopy. Material irradiated to 18 dpa (displacements per atom) using neutrons and to 2.3 and 7 dpa by protons was investigated. The results show that Fe is lost from Zr-Nb-Fe-SPPs during both neutron and proton irradiation. Prior to irradiation, Fe was detected at the interface of β-Nb-SPPs. This Fe enrichment is also dispersed during irradiation. Qualitatively, excellent agreement was found regarding the elemental redistribution processes observed after proton and neutron irradiation.