Complex Mg-based hydrides obtained by mechanosynthesis: Characterization and formation kinetics

Ternary Mg2THyMg2THy, as well as quaternary Mg2T0.5T0.5′Hy, Mg-based hydrides with T,T′=Fe,Co,NiT,T′=Fe,Co,Ni were synthesized by reactive mechanical alloying in hydrogen atmosphere at 0.3 MPa. The reaction progress was followed from the H2H2 absorption during milling until a steady state was reached, and different kinetic behaviors were found in each case. These regimes could be related to the presence or absence of hydrogen-free Mg2TMg2T intermetallic precursors in the respective phase diagrams. The steady state samples were characterized by X-ray diffraction and differential scanning calorimetry, and those systems including Fe were studied, in addition, with Mössbauer spectroscopy.