HYDROGEN SORPTION IN AMORPHOUS NI(ZR,TI)-ALLOYS

Hydrogen absorption and desorption were studied in Ni64Zr36 and Ni62Ti29Zr9, obtained in the amorphous state by melt spinning, and in crystalline Ni64Zr36. Pressure-Composition isotherms were measured with a volumetric method. The isotherms of the amorphous alloys did not exhibit a pressure plateau. The hydrogen-to-metal ratio H/M of amorphous and crystalline Ni64Zr36 at a hydrogen pressure of 3.4 MPa and a temperature of 333 were found to be 0.54 and 0.66 respectively. In none of the isotherms measured Sieverts' Law is obeyed. The ribbons remained amorphous upon hydriding and dehydriding as shown by X-ray and caloric measurements (DSC-2). Upon hydrogen absorption the amorphous ribbons increased with about 3.5% in length and width. The ribbons became brittle but did not pulverize, in contrast to the crystalline alloy. The hydrogen sorption rate of the crystalline material was somewhat larger than that of the amorphous ribbons. © by Akademische Verlagsgesellschaft