THE ROLE OF Ni ADDITIVE, SIZE FACTOR AND SURFACE CHEMICAL STATE IN DECREASING TEMPERATURE AND IMPROVING DECOMPOSITION KINETICS OF THE NANOSIZED MgH2 HYDRIDE PHASE OF MECHANICAL ALLOYS Mg +10wt.% Ni AND MgH2 +10wt.% Ni

Abstract Three hydride-forming mechanical alloys of magnesium with the addition of 10 wt % Ni were synthesized. The mechanical alloys were derived by the method of reactive mechanical alloying (RMA) by different ways, in particular by reactive grinding of Mg powder with Ni additive and by the same reactive grinding under the same conditions of two MgH2 powders made using different methods with the same Ni additives. The effect of this Ni additive and the method of obtaining mechanical alloys (MAs) on the hydrogen sorption properties, temperature and kinetics of decomposition of their MgH2 hydride phase was investigated by isobaric thermodesorption spectroscopy (TDS) at a constant hydrogen pressure of 0.1 MPa. The appreciable influence of the applied method of obtaining MAs on the kinetics of the process of hydrogen desorption is established and the mechanism of the specified influence is investigated