Positron annihilation spectroscopy study of defects in hydrogen loaded Zr-1Nb alloy

The purpose of this work is to implement the positron lifetime and Doppler broadening techniques for the study of hydrogen-induced defects in Zr-1wt% Nb (hereinafter Zr-1Nb) alloy. It was shown that spark cutting is an appropriate instrument to obtain a pair of Zr-1Nb samples with the same hydrogen content for the sandwich geometry and does not introduce open-volume defects in them during the cut. The ab initio calculations were implemented to evaluate the positron annihilation characteristics for expanded crystal lattice, Zr with absorbed hydrogen, Zr-vacancy and Zr-vacancy-hydrogen complexes. The type of defects created in Zr-1Nb alloy loaded with hydrogen from the gas phase up to various hydrogen concentrations was studied. The main types of defects induced by hydrogen loading are vacancy-hydrogen complexes and dislocations. The processes of crystal lattice expansion and hydrogen dissolution in the lattice were studied. (C) 2019 Published by Elsevier B.V.