Characterization of heavy ion induced defects in Zr-2.5 wt. % Nb by grazing incidence X-ray diffraction

Abstract

Zr-2.5 wt. % Nb alloy is used as a pressure tube material in pressurized heavy water reactor (PHWR). It is one of the most critical component which decides the life of the reactor. The in-reactor degrading phenomenon of prime concern is dimensional changes caused by irradiation induced creep and growth processes. The present study aims to understand the mechanism of irradiation damage by irradiating the alloy with heavy ion. Heavily charged Ar9+ ions have been used, as it leads to dense cascade similar to those observed in neutron beam damage. Such type of irradiation study would facilitate larger damage of material in a shorter time. Zr-2.5 %Nb alloy samples were irradiated using 315 keV Ar9+ ion for different durations. The irradiation doses were varied from 3.1x1015 to 4.17x1016 Ar9+/cm2. Grazing incidence X-ray diffraction (GI-XRD) is known as a direct, non-destructive, surface-sensitive technique for characterization of materials. Using GI-XRD domain size, micros train by Williamson hall method, dislocation density by line profile analysis (LPA), residual stress, and depth profiles of irradiated phase distributions were calculated. The analysis revealed that there is a significant decrease in domain size with corresponding increase in microstrain and dislocation density with irradiation dose.