Abstract
The protium absorbing/desorbing characteristics of the rapidly-solidified and mechanically-ground Mg2Ni–Mn alloys with different Manganese content were investigated. High Manganese additions do not result in great changes in plateau pressure of Mg2Ni phase. But in mechanically-ground specimens of Manganese-added alloys, a new plateau appears during absorption of protium at a pressure higher than the plateau pressure of Mg2Ni phase. In rapidly-solidified and mechanically-ground specimens of Manganese-added alloys, protium content at low temperature increases. By exposing specimens for many hours in argon atmosphere at room temperature after hydriding at 250°C, the desorbed protium content increases and the protium desorption temperature decreases. This implies that the amount of microtwinning decreases with increasing elapsed time, and then protium desorbing temperature changes to lower values. Formed MgH2 phase in high Manganese-added alloys desorbs protium at low temperature probably due to contractive strain generated at the interface between the MgH2 phase and intermingled Mg2NiH4 phase as the later desorbs protium.
