Solid-State Synthesis of Mg₂Ni by the Bulk Mechanical Alloying

Abstract

Mg₂Ni alloy has been and is still highlighted as a candidate hydrogen storage material to be working instead of LaNi₅, which is a typical commercial material at present. This alloy is superior to other hydrogen storage alloys with respect to hydrogen absorbing capacity, light weight, long-life usage as a battery and adaptivity to Ni-Cd type batteries. New processing is required to make precise control of chemical composition in alloying, to reduce absorbing temperature of hydrogen and to avoid from various contaminations. In the present study, the bulk mechanical alloying is applied to solid-state synthesis of Mg₂Ni alloys instead of the milling-type mechanical alloying or the conventional P/M approaches. The present method is favored for the precise control of chemical composition within the tolerance of 1% or less, the fabrication of dense green compact of Mg₂Ni, which prevents itself from burning or oxidation and, the microstructure control to yield nano-grained powder compact. Furthermore, low temperature phase can be available to lower hydrogen absorbing temperature. XRD, TEM and Sievert method are utilized to make characterization of the synthesized Mg₂Ni and to evaluate its thermo-dynamic properties, respectively.