Hydrogen evolution from cathodically charged Ti3Al-based titanium aluminium alloy

A single-phase Ti3Al-based titanium aluminium alloy, Ti-25Al, was cathodica lly charged with hydrogen in a 5% H2SO4 aqueous solution for charging times up to 43.2 ks, and the formation and dissociation of a hydride, hydrogen e volution behavior and total hydrogen uptake were investigated by means of X -ray diffractometry and thermal desorption spectroscopy (TDS). After cathod ic hydrogen charging, hydrogen concentrated mainly at the surface of the sa mple as a hydride phase, whose crystal structure probably is of a hexagonal type with the lattice parameters of a=0.60 nm, c=0.47 nm. Hydrogen also in duced cracks and pits at grain boundaries or within grains. Three kinds of TDS peak, for which one corresponded to the hydride dissociation and the ot hers presumably corresponded to trapping of hydrogen, could be found after longer hydrogen charging. The apparent hydrogen uptake in the Ti-25Al alloy increased with increasing charging time and the uptake level after chargin g for 43.2 ks was estimated to be about 700 wppm. (C) 1999 Elsevier Science S.A. All rights reserved.