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
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