Study of Zr-2.5Nb-0.5Cu CANDU Spacer Material: Microstructure and Irradiation Effect

Abstract

In this study, the microstructure and stability of precipitates in Zr-2.5Nb-0.5Cu alloy under heavy ion irradiation was investigated. Results show that three types of microstructure co-exist in the alloy: Widmansttatten structure, α-Zr grains without precipitates and α-Zr grains with precipitates. In the meantime, three types of second phase particles are detected: β-Nb, Zr₂Cu and Zr₂Fe, which have different distributions within the microstructure. The structure has significant effects on the precipitate stability under irradiation. The precipitates are much more stable in microstructures with multiple boundaries (martensitic structure) than in coarse grain microstructures.