An amorphous-to-amorphous transition in Ni–Zr–B alloys as probed by hydrogen storage

Abstract

The hydrogen occupation characteristics of the ternary amorphous alloy system Ni–Zr–B are investigated using gas-phase and electrochemical hydrogen-absorption techniques. Boron concentrations of as little as 1% are observed to cause large changes in the hydrogen storage properties relative to the binary Ni–Zr. Generalizations of a site statistical model, which accurately accounted for H storage in thebinary Ni–Zr and is based on tetrahedral interstitial hydrogen sites, cannot account for the hydrogen absorption properties of the boron-containing alloys, suggesting a structural transition between two amorphous phases induced by only 1% boron. A simple model in which the new amorphous phase stores H in higher-coordinated interstitial sites is shown to be consistent with the electrochemical and gas-phase data.