Synthesis, Hydrogenation and Mechanical Milling of Pseudo-Binary Zr(NbxV1-x)2 (0≤x≤0.65) Alloys

Abstract

AB2 metallic alloys provide large quantities of Laves phases when prepared using conventional thermal routes. In the present work the crystallography, hydrogenation behavior and mechanical milling (MM) effects of the pseudo-binary Zr(NbxV1-x)2 (0<x≤0.65) system are studied. It is found that the partial replacement of V by Nb atoms leads to the formation of cubic C15 (0<x≤0.20) and hexagonal C14 (0.35≤x≤0.65) Laves phases. For x≤0.20, the niobium additions promote a slight increase of the hydrogen storage capacity by the C15 phases. For 0.35≤x≤0.65, the reduction of the molar fraction of the C14 phase promotes an increase of the alloy hydrogen storage capability. Iron incorporation plays a major role on the type of final mechanically-milled Zr-Nb-V alloys obtained: a transformation from Laves phases (C14 and C15) to an fcc (Fm3m) one; while, in the absence of Fe, amorphization of the system was observed, as predicted by Miedema Model. As a general result, the mechanical milling of the Zr-Nb-V alloys results in a reduction of the hydrogen storage capacity, at least for long processing times.