Interestingly, we found that for the most sta-ble alloy configurations of all three compositions, the initial BCC alloy configurations remain as BCC after DFT structural optimizations, and the initial FCC alloy configurations transform into BCC after DFT structural optimizations, which implies the intrinsic instability of FCC alloy structures. On the other hand, for the hydrides of each alloy composition, the initial BCC hydrides undergo significant structural relaxations and no space group symmetry can be identified from the optimised structures, while the initial FCC hydrides remain as FCC after DFT structural optimizations. It remains to be seen why the alloy prefers the BCC structure and the hydride prefers the FCC structure for this family of HEAs, and how such structural transition may affect the hydrogen absorption thermodynamics and kinetics.