Gaseous Hydrogen Absorbing/Desorbing Kinetics Performances Of As-cast And Quenched (Mg₂₄Ni₁₀)_1-xSm_x（x=0-0.2） Alloys

This paper mainly concentrated on the research of Mg-based hydrogen storagealloys, especially on the influence of Sm addition and metal spinning for microstructureand gaseous hydrogen absorbing/desorbing kinetics performances of Mg2Ni alloys.The (Mg₂₄Ni₁₀)_1-xSm_x（x=0-0.2） alloys were prepared by medium frequencyinduction furnace and metal spinning under vacuum atmosphere. The phase structureand compositions of the experimental alloys were determined by X-ray diffractometer.The morphologies of the as-cast alloys were examined by SEM. The microstructures ofthe as-spun alloys were tested by HRTEM. The gaseous hydrogen absorbing/desorbingkinetic performances of experimental alloys were measured by PCT equipmentprovided by Beijing non-ferrous metal research institute.The results of XRD and SEM revealed that the as-cast (Mg₂₄Ni₁₀)_1-xSm_x（x=0-0.2）alloys hold a multiphase structure. The Sm addition changed the microstructure and thegrains were refined obviously. The analysis of TEM showed that the microstructures ofas-spun alloys were refined and the chaos of atomic arrangement were increased, whichproduced a lot of amorphous phases and structure defects.We have found that the amount of hydrogen absorption of as-cast （Mg24Ni10）1-xSmx（x=0-0.2） alloys increased as the pressure raised. However, the effect oftemperature on the hydrogen absorption was complicated. Note that alloys different incomponents had their own optimum temperature of hydrogen absorption, and that of thealloys with Sm content （x=0、0.05） was200℃with hydrogen absorbing amount showinga declining tendency as the temperature increased. For the Sm content （x=0.1、0.15、0.2）alloys, the optimum hydrogen absorption temperature was250℃. As the increasing of Smcontent, the hydrogen absorption first increased then decreased, and reached themaximum values when x=0.1. However, the kinetics of as-cast alloys continued toimprove as the increase of Sm content.The hydrogen desorbing capacity of the as-cast (Mg₂₄Ni₁₀)_1-xSm_x（x=0-0.2） alloysremarkably raised with increasing temperature. The adding of Sm can enhance thehydrogen desorption as well as the desorbing kinetics of Mg2Ni alloys.