Observation of second-phase particles in bulk zirconium alloys using synchrotron radiation

To further advance the mechanistic understanding of microstructural evolution in zirconium alloys for high burnup applications, it is important to obtain a quantitative measurement of the volume fractions of second-phase precipitates present in the bulk alloys as a function of the heat treatment and irradiation fluence. In this work, X-ray diffraction from a synchrotron radiation source was used to identify and follow the growth kinetics of second-phase particles in zirconium alloys. The high energy flux, energy resolution and signal-to-noise ratio of this light source allowed us to study the very small (<0.2–0.4%) precipitate volume fractions in these alloys. A preliminary calculation of the precipitate volume fraction as a function of cumulative annealing parameter (CAP) showed the precipitate volume fraction increases rapidly above 10−19 h and saturates at about 10−17 h.