Solid-State Hydrogen Storage Properties of Ti–V–Nb–Cr High-Entropy Alloys and the Associated Effects of Transitional Metals (M = Mn, Fe, Ni)

Abstract Recently, high-entropy alloys (HEAs) designed by the concepts of unique entropy-stabilized mechanisms, started to attract widespread interests for their hydrogen storage properties. HEAs with body-centered cubic (BCC) structures present a high potential due hydrogen-to-metal ratio (up H / M = 2) and vastness compositions. Although many studies reported rapid absorption kinetics, investigation desorption is missing, especially in BCC HEAs. We have investigated crystal structure, microstructure performance series Ti–V–Nb–Cr system. Three types TiVCrNb (Ti 4 V 3 NbCr 2 , Ti Nb Cr ) close atomic radii different valence electron concentrations (VECs) were single phase CALPHAD method. The three fast kinetics reach up 2. Particularly, alloy shows capacity 3.7 wt%, higher than other ever reported. dehydrogenation activation energy HEAs’ hydride has been proved decrease decreasing VEC, which may be weakening atom atom. Moreover, ( Mn, Fe, Ni) also synthesized destabilize hydrides. addition Fe Ni lead precipitation Laves phase, however, did not improve further because own excellent absorption. With increasing content there appear more pathways so that hydrides are easily dissociated, provide new insights into how achieve at room temperature.