Hydrogen desorption from pure titanium with different concentration levels of hydrogen

Hydrogen evolution behaviors for pure titanium plate samples, in which hydrogen has been thermally charged with gas phase hydrogen at a pressure of 0.1 MPa, were investigated by means of thermal desorption spectroscopy (TDS). Hydrogen concentration in the samples were varied from an extremely low level to a high one, as to form the hydride, by changing the charging times (up to 20 h) and temperatures (398-773 K). After hydrogen dissolution of low concentration level at the initial stage of the dissolution, four kinds of hydrogen evolution peaks were found at 850, 900-950, 1050 and 1150 K in TDS spectra. The hydride formation occurred abruptly at charging temperatures more than 680 K and at the hydrogen concentration level of more than 15-16 at.%, leading final hydrogen concentration of more than 47 at.% hydrogen. For the sample with high hydrogen concentration level as to form the hydride, another TDS peak at 750 K was observed in addition to that at 850 K. The sample hydrogenated evolved a large amount of hydrogen accompanying with a TDS peak from 550 to 900 K. The composition of the hydride was estimated to be TiH_x (x:1.1).