Influence of Ti, Mn, Fe, and Ni addition upon thermal stability and decomposition temperature of the MgH_2 phase of alloys synthesized by reactive mechanical alloying

摘要

Influence of addition of some transition metals (TMs), mainly Ti, Mn, Fe and Ni, to magnesium upon thermal stability of the hydride phase MgH_2 synthesized due to reactive mechanical alloying (RMA) in hydrogen atmosphere at pressure 1.2 MPa was studied employing the thermodesorption spectroscopy (TDS) method. The TDS spectra registered differ from each other by their shapes and fine-structure peculiarities. This fact allows to conclude about a different influence of the TMs under consideration upon the feature of hydrogen distribution on location sites in the hydride phase and, consequently, upon its decomposition temperature. We have made an attempt to elucidate the origin of the mentioned influence of the TMs upon the effects derived. A correlation between the degree of dispersion of TM alloying the MgH_2 hydride and its decomposition temperature was observed. It has been established that, addition of 10 wt percent Ti reveals the maximum influence on decreasing decomposition temperature of the hydride phase. The X-ray photoelectron O 1s core-level spectrum of the specimen contained the addition of 10 wt percent Ti shows decreasing a quantity of oxygen-contained structures, catalyst poisons, adsorbed on its surface.