La-Mg-Ni系储氢合金的容量衰减与组织结构

Capacity Decay and Microstructure of La-Mg-Ni System Hydrogen Storage Alloy

为了研究AB 2型La-Mg-Ni系储氢合金的容量衰减以及循环前后合金的组织结构,采用Sieverts法测试了LaSmMgNi 4.1快淬态合金的吸放氢量,用X射线衍射分析(XRD)、扫描电子显微镜(SEM)和高分辨透射电子显微镜(HRTEM)分别测试和观察了循环前后合金的相结构、颗粒形貌以及原子排列。结果表明,合金的吸放氢量随着循环次数增加发生衰减,合金的吸放氢衰减速率与循环阶段有关。合金由不同生长方向、不同尺寸的柱状晶组成,成分基本均匀,主要由(LaSm)MgNi 4主相和LaNi 5相组成,相组成的组织为晶态。经过吸放氢循环后,合金由大量非晶和少量晶态组成。随着循环次数增加,合金颗粒粉化与蓬松严重。

In order to study the capacity decay of AB 2 type La-Mg-Ni system hydrogen storage alloy and the microstructure of the alloy before and after cycling,the hydrogen absorption and desorption capacity of the alloy were measured by Sieverts method.The phase structure,particle shape and atomic arrangement of the alloy before and after cycling were measured and observed by X-ray diffraction(XRD),Scanning electron microscopy(SEM)and high resolution transmission electron microscopy(HRTEM).The results show that the amount of hydrogen absorption and desorption decreases with the increase of cycle times,and the rate of hydrogen absorption and desorption is related to the cycle stage.The alloy is composed of columnar crystals with different growth directions and sizes,and its composition is basically uniform.It is mainly composed of(LaSm)MgNi 4 main phase and LaNi 5 phase.The structure of the phase is crystalline.After hydrogen absorption and desorption cycle,the alloy is composed of a large amount of amorphous and a small amount of crystalline.With the increase of the number of cycles,the powder and fluffy of alloy particles are severe.