Hydriding properties of amorphous Ni–B alloy studied by DSC and thermogravimetry

Abstract

The hydrogenation behaviour of melt-spun Ni 81.5B 18.5 amorphous alloy was studied by means of differential scanning calorimetry (DSC) and thermogravimetry (TG) and compared with the hydriding properties of a Fe–B–Si glass. It was found that the amorphous Ni–B alloy absorbs larger amounts of hydrogen than the Fe–B–Si glass, as the initial kinetics of hydrogen absorption and desorption of both the alloys are comparable. Hydrogen absorption and desorption reactions in Ni–B were observed to proceed with similar rates at ca. 300 K. The hydrogen desorption is revealed in DSC as an endothermic peak in the 350–450 K range, preceding the crystallization peak of the amorphous alloy. The enthalpy of hydrogen desorption (Δ H des=22 kJ/mol H 2) for Ni–B was found to be smaller than that for the Fe–B–Si glass, which finding is in contrast to the results on hydrogen diffusion in crystalline αFe and Fe-based alloys and Ni and Ni-based alloys. The hydrogen desorption temperature and enthalpy for Ni 81.5B 18.5 were found to be independent of the amount of hydrogen absorbed.