Hydrogen absorption in MgNiFe alloys

The hydrogenation properties of the alloys of overall formula Mg₂Ni_1?xFe_x (x ? 0.37) have been studied. In this range of composition multi-phase alloys were obtained containing Mg₂Ni, Mg and more or less finely dispersed Fe in different coordination as proved by the EXAFS technique and Mössbauer spectroscopy. There is no significant substitution of Ni by Fe atoms in the Mg₂Ni lattice. Two or three plateau-pressures are observed on the pressure-composition isotherms of the hydrides with the heats of formation in the range ?18.4 to 20.4 kcal/mol H₂ (?77 to ?85.4 kJ/mol H₂). The hydrides of the Fe containing alloys show higher desorption rates of hydrogen compared to the pure Mg₂Ni hydride.