REVERSIBLE AND IRREVERSIBLE HYDROGEN ABSORPTION IN NI-67-XCUXZR33 GLASSES MONITORED BY IN-SITU RESISTIVITY MEASUREMENTS

The process of hydrogen absorption and desorption are investigated in Ni67-xCuxZr33 glassy alloys by in situ resistivity measurements. The c yclic charging and discharging process has been monitored by conventio nal DC method using a computer-controlled system, exposing the samples to hydrogen of 6 MPa pressure at 293, 328 and 373 Ki respectively. No rmalized resistivities as a function of charging and discharging times are compared for the first and repeated cycles, Separate samples, tak en from specific points of cycling, were investigated by transmission electron microscopy (TEM) measurements. Hydrogen content (HIM ratio) w as determined by weight measurements, and checked by gas chromatograph y, which is combined with an appropriate vacuum extraction and heating technique of the samples. A gradual hydrogen-induced phase separation could be detected on the samples by scanning transmission electron mi croscopy (STEM) with increasing number of the cycling. (C) 1997 Elsevi er Science S.A.