In-situ characterization of the Mg22Ti22Nb22Cr11Mn11Ni11 and Mg22Ti22Nb22Fe11Co11Ni11 high entropy alloys for hydrogen storage

Abstract

Developing safe, reliable, efficient and cost-effective materials for hydrogen storage is a scientific and technological challenge that must be overcome to leverage a clean and renewable hydrogen-based energy system. Several papers have shown that metal hydrides, such as MgH2 and TiFeH, for instance, are promising materials for this application. Recently, it was shown that the equiatomic TiVZrNbHf high entropy alloy (HEA), which crystallizes as a single multicomponent solid solution, is capable to store 2.5 hydrogen atoms per metal atom, which is considerably higher than conventional metal hydrides such as MgH2. Previous results from our research group demonstrated that the MgZrTiFe0.5Co0.5Ni0.5 HEA also has interesting hydrogen storage properties. In the first part of this master's project, three new HEA, namely Mg14Ti18Nb35Cr5Mn18Ni10, Mg30Ti14Nb23Cr15Mn5Ni13 and Mg22Ti22Nb22Cr11Mni11Ni11, were studied. These alloys absorbed up to 0.25wt.%, 1.4wt.% and 1.2wt.% of hydrogen, respectively, in 1.5 hour under 350 ºC and 6.0 MPa of H2 pressure. Based on the first results, a new alloy composition is being proposed, namely Mg22Ti22Nb22Cr11Mni11Ni11. This project proposes to evaluate the desorption/absorption behavior and thermal stability of the Mg22Ti22Nb22Fe11Ni11Co11 and Mg22Ti22Nb22Fe11Ni11Co11 HEAs using in-situ XRD and high-pressure DSC techniques. This project will be carried out at the Max-Planck-Institut für Kohlenforschung, Germany, a worldwide renowned institute in the field of materials for hydrogen storage, under the supervision of Dr. Michael Felderhoff. (AU)