Improvement of Protium Absorption/Desorption Characteristics of Mg-x mass%LaNi<SUB>5</SUB> (x=50, 70) Composites by Interface-control

Abstract

An attempt is made to form composites of pure magnesium that has high hydrogen capacity of about 7.6 mass% and LaNi5 alloy that is capable of protium absorption/desorption at relatively low temperatures by mechanical alloying (MA) for the utilization of synergy effect to acquire both high capacity and ability to absorb/desorb protium at low temperatures. The Mg–LaNi5 composites have a well-bonded and uniform structure. The maximum protium content of a specimen of mechanically-alloyed Mg–50 mass%LaNi5 composite is 2.77 mass% at 40°C. Furthermore, the maximum protium content of a specimen of mechanically alloyed Mg–70 mass%LaNi5 composite is 1.81 mass% at 40°C, and the protium absorption kinetics of the composite become fast at the initial region of the hydriding curve. Consequently, the results suggest the occurrence of synergy effect during the absorption process since the hydrogen capacity of LaNi5 phase of the composites is lower than 2.77 mass% and 1.81 mass% at 40°C and Mg cannot absorb protium at a relatively low temperature of 40°C.