Positron annihilation study of recrystallization behaviour in Zr2.5%Nb alloy

In CANDU reactors Zr 2.5%Nb alloy is used as pressure tube material due to low neutron absorption cross section, a high resistance to corrosion in water, high strength and good creep resistance. The two phase alloy consists of α‐fcc and β‐bcc. The recrystallization behavior of Zr2.5Nb strongly depends on morphology and distribution of second phase. In this study, the material was deformed to 60% and then was recrystallized in α + β region for different duration (i.e. 2 minutes to 14 days at 700 °C). The recrystallized microstructure was characterized by Orientation Imaging Microscopy (OIM). The evolution of microstructure was examined by Positron Lifetime Spectroscopy and Doppler Broadening measurement for each heat treated samples. Results from positron annihilation studies and other microstructural examination have been used to rationalize the recrystallization aspects, defects and β‐phase distribution. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)