Nanocrystalline and non-crystalline hydrides synthesized by controlled reactive mechanical alloying/milling of Mg and Mg–X (X = Fe, Co, Mn, B) systems

Abstract

The results of the mechano-chemical synthesis of hydrides by controlled reactive mechanical alloying/milling (CRMA/CRMM) of Mg, 2Mg–Fe, 2Mg–Co, 3Mg–Co, 3Mg–Mn and Mg–2B systems under hydrogen in the magneto-mill Uni-Ball-Mill 5, are discussed. Mostly nanocrystalline hydrides have been synthesized in all the above systems while non-crystalline (possibly amorphous) hydrides have also been synthesized in the 2Mg–Fe system. Double DSC hydrogen desorption peak is observed for a single-phase β -MgH 2 hydride and a single desorption peak is observed for a duplex hydride ( β -MgH 2 + Mg 2FeH 6). The effects of initial nanograin (crystallite) size (after synthesis by CRMA) and alloy composition on the DSC hydrogen desorption temperature of β -MgH 2 and Mg 2FeH 6 are presented.