Microstructure of Zirconium Alloys and Effects on Performance

Microstructure plays a central role for the efficient use of zirconium alloys during service in nuclear reactors. The in-reactor performance of components made from zirconium alloys depends on the environment – neutron flux, high temperature and water chemistry – and the properties of the metal – corrosion resistance and mechanical strength and ductility. These properties are controlled by the microstructure of the alloy.

Microstructure describes the crystal phases present, their spatial and orientation distributions and their defect structure. The initial microstructure is determined by the alloy composition and the various working processes and heat-treatments required to fabricate the component and meet various specifications.

During service the microstructure is modified by interactions with neutrons and water. Research and development is aimed at optimising microstructures to resist the deleterious effects induced by the reactor environment.

This Report provides examples illustrating how microstructures are modified during fabrication and service and how these microstructures affect properties.