A Screening Method for Hydrogen Storage Alloys


Abstract: A screening method is described that can be used for rapid evaluation of metallic systems for their hydrogen storage potentials. The method makes use of a single sample of compacted elemental powders that are sintered to yield nearly all phases and compounds of the respective phase diagram. The sample is then evaluated in a Sievert's type apparatus by charging with hydrogen of initially known pressure and recording the pressure change as a function of temperature. Deviation from linearity in the pressure-temperature relationship is a sign of hydrogen sorption in that particular system. As to which phase (or phases) absorbs hydrogen is determined with the detailed comparison of X-ray analysis of the sample before and after hydrogenation. The method is applied to Mg-Al binary with success. In Mg-Ni-Al ternary, the method is partially successful due to the limited number of phases that could be formed. This could be remedied either by mechanical milling of powders before compaction or, preferably, by splitting the ternary system into regions of similar solidus temperatures.

Keywords: Combinatorial method, hydrogen storage, internal reaction, Mg-Al, Mg-Ni-Al, Mg_{17}Al_{12}

Full Text: PDF