The effect of copper on irradiation-induced growth mechanisms in the W13 alloy

Irradiation-induced growth (IIG) is a detrimental effect on nuclear fuel assembly materials such as zirconium (Zr) alloys which is characterised by a volume conserving shape change. IIG results from the formation and evolution of <a> and <c> type dislocation loops in the highly textured hexagonally cose-packed alpha-phase Zr microstructure. Alloying additions may effect the rate of IIG in Zr alloys through their interactions with dislocation loops, consequently understanding how alloying elements behave in Zr is important to understand how they influence dislocation loop evolution. Cu is an increasingly more common addition in Zr alloys because of its beneficial effects on corrosion resistance, however, it is largely unknown how Cu interacts with dislocation loops and consequently how it could effect IIG rates. The Zr-Nb-Sn-Cu-Fe W13 alloy was developed by Westinghouse Electric Company, and was proton irradiated at the Dalton Cumbria Facility and neutron irradiated in the BOR-60 reactor. Transmission electron microscopy, X-ray diffraction line profile analysis and atom probe tomography were employed to evaluate the microstructural and dislocation loop evolution in the irradiated W13 samples, informing us on its potential influence on IIG.