Kinetics of hydrogen absorption in Zr-based alloys

The kinetics of hydrogen absorption in Zr-based alloys Zr-2.5Nb, Zr-10Nb, Zr-2.5Nb-3Ta and Zr-10Nb-12Ta have been investigated in the temperature range 673-973 K at 1 bar hydrogen pressure. The improvement in hydrogen kinetics and a slight decrease of maximal amount of hydrogen absorbed were observed upon cycling. The rate determining steps are as follows: geometrical contraction for all samples except Zr-10Nb-12Ta; diffusion in the beginning for Zr-10Nb at 973 K Zr-2.5Nb-3Ta at 673 K and 973 K; first order reaction Zr-10Nb-12Ta at all temperatures. The amount of additives, Nb and Ta, is found to have major influence on the mechanism of the absorption process. (C) 2013 Elsevier B. V. All rights reserved.