The changes in the electronic structure of B2 FeAl alloy with a Fe antisite and absorbed hydrogen

The electronic structure and bonding in a B2 FeAl alloy with and without hydrogen interaction with a Fe antisite were computed using a density functional theoretical method. The hydrogen absorption turns out to be a favorable process. The hydrogen was found close to an octahedral site where one of its Al capped is replaced by a Fe antisite. The Fe–H distance is of 1.45 Å same as the Al–H distance.The density of states (DOS) curves show several peaks below the d metal band which is made up mostly of hydrogen based states (>50% H1s) while the metal contribution in this region includes mainly s and p orbitals.An electron transfer of nearby 0.21e− comes from the metal to the H. The overlap population values reveal metal–metal bond breaking, the intermetallic bond being the most affected. The H bond mainly with the Al atom and the reported Fe–H overlap population is much lower than that corresponding to FePd alloys and BCC Fe. The changes in the overlap population show the Fe–Al bond is weakened nearly 41.5% after H absorption, while the Fe–Fe bond is only weakened 34.5%. H also develops a stronger bond with the Al atoms. The main bond is developed with Al being twice stronger than Fe–H.