Positron annihilation in Zr-0·5 Nb alloy

Abstract

The measurement of coincidence counting rate at the peak of the angular correlation curve shows a considerable difference between the recovery behaviour of coldworked Zr-0.5 Nb alloy from that reported for pure zirconium. This difference in behaviour illustrates the point-defect activity during the course of isochronal annealing in this alloy. The recovery spectrum can be understood in terms of the vacancy-solute entrapment upto about 250°C. In the next stage the release and clustering effects of vacancies are indicated prior to their elimination. The study thus demonstrates the effect of alloying element on the defect mobility and associated point defect interactions in Zr.

Post irradiated microstructural characterization of Zr–1Nb alloy by X-ray diffraction technique and positron annihilation spectroscopy

“…As observed in figure 7(b), the initial increase in I 2 can be attributed to the increase in the concentration of mono-vacancies resulting from the dissociation of vacancyimpurity complexes. Upadhyaya and Muraleedharan (1987) observed the dissociation of vacancy-impurity complexes in Zr-0·5Nb system around a temperature of 523K. According to Cottrell (1967), the following relation approximately describes the binding energy of a vacancy with a foreign atom which has a size misfit, "η", with the matrix lattice:…”