Mg-containing multi-principal element alloys for hydrogen storage: A study of the MgTiNbCr0.5Mn0.5Ni0.5 and Mg0.68TiNbNi0.55 compositions

Thermodynamic modelling of hydrogen-multicomponent alloy systems: Calculating pressure-composition-temperature diagrams

“…Nygard et al [12] reported the formation of intermediate hydrides with undistorted BCC structure for different alloys such as TiVNb and TiVCrNb. The same was observed for the Mg0.68TiNbNi0.55 alloy in [13]. C. Zlotea et al [11] reported the formation of an intermediate hydride with body-centered structure (BCT) for the TiZrNbHfTa alloy.…”

“…Moreover, an undistorted BCC monohydride was also observed for some of them, such as TiVNb and TiVNbCr. Such BCC monohydride was also reported for some Mg-containing HEA such as the Mg0.68TiNbNi0.55 alloy [13]. The understanding of the hydrides' stability at different pressures and temperatures is essential to determine the applicability of an alloy.…”

“…The δ-phase is a face centered cubic structure (FCC) with H atoms at the T-sites in a CaF2-type structure. This phase is usually observed during hydrogenation of pure elements such as VH2, NbH2, TiH2, and for several multicomponent BCC alloys such as TiVNb, TiVNbCr and TiNbZrHfTa [12,13]. δ-phase with BCT structure has also been reported for the TiVZrNbHf alloy [9,17].…”

“…In this work we revisited the thermodynamic fundamentals of M-H systems and present a thermodynamic model to calculate the pressure-composition-temperature (PCT) diagram of multicomponent M-H systems. Since most of the recent works in multicomponent alloys for hydrogen storage deals with BCC alloys [9,[11][12][13][14][15][16][17], this class of alloys was firstly considered. The enthalpy terms for eight metal elements, namely Ti, V, Cr, Ni, Zr, Nb, Ta, and Hf, which are the components of the alloys considered here, were parametrized by combining experimental data and total energy calculations trough density functional theory (DFT).…”

A First-Principles Study of Hydrogen Desorption from High Entropy Alloy TiZrVMoNb Hydride Surface

“…Among the investigations of hydrogen storage of HEAs, efforts have been made to study the desorption properties of HEA hydrides. For HEAs such as TiZrVHfNb [19], TiZrHfMoNb [21], MgZrTiFe 0.5 Co 0.5 Ni 0.5 [24], TiZrNbHfTa [25], TiZrNbTa [22], TiVZrNb [26], MgTiNbCr 0.5 Mn 0.5 Ni 0.5 [27], MgVAlCrNi [28] and MgTiVCrFe [29], it has been found that hydrogen desorption happens at temperature of above 200 • C. Recently, several works of research have been devoted to reducing the desorption temperature [23,[30][31][32]. The hydrogen desorption properties of a series of TiZrHfMoNb HEAs with Metals 2021, 11, 553 2 of 13 different Mo concentrations have been investigated experimentally and theoretically by Shen et al [30], who found that the thermal stability of the TiZrHfMoNb hydrides decrease with increasing Mo concentration, which is mainly attributed to the smaller cell volume of the TiZrHfMoNb hydride for higher Mo concentrations.…”