Hydride formation and interfacial enthalpies between hydrogen and Mg mixtures with immiscible elements/alloys

This study investigates effects of immiscible alloying elements and hydrogen on phase stability in Mg-based systems using extended Miedema's semi-empirical model. Evaluated systems were Mg-M (M = Fe, Cr, Mn, Nb, Ti, V, Zr) and Mg-TiM-based alloys (M = Fe, Cr, Mn, Nb, V, Zr) and their hydrides. Results reveal Mg-metal/alloy systems are mostly immiscible, with Nb and TiCr exhibiting strong repulsion. Hydrogen's potential in stabilizing interfaces through negative enthalpy interactions is highlighted, alongside its segregation tendency impacting Mg-based system stability and hydrogen storage potential. Exceptions occur in Fe- and Mn-containing systems, where hydrogen migrates to Mg matrix. Correlation between interface energies and interfacial enthalpies in the presence of hydrogen underscores negative interface energies as a likely stabilizing agent for nanostructures, aligning with theoretical and experimental data. These findings demonstrate the extended Miedema's model as a powerful tool for predicting hydride stability and designing Mg-based materials for solid-state hydrogen storage.