快速凝固MlNi_(4.0)Al_(0.3)Si_(0.1)Fe_(0.6)无Co贮氢电极合金的微结构和电化学性能  

Microstructure and Electrochemical Properties of the Rapid Solidified Co-Free MlNi_(4.0)Al_(0.3)Si_(0.1)Fe_(0.6 )Hydrogen Storage Electrode Alloys

作　　者：陈贤礼[1] 雷永泉[1] 廖彬[1] 陈立新[1] 张志鸿[1] 

机构地区：[1]浙江大学,浙江杭州310027

出　　处：《稀有金属材料与工程》2005年第5期811-815,共5页Rare Metal Materials and Engineering

基　　金：国家自然科学基金重点项目资助(50131040)

摘　　要：研究了单辊快淬快速凝固处理对无Co贮氢电极合金MlNi4.0Al0.3Si0.1Fe0.6的微结构和电化学性能的影响。XRD分析表明,快凝合金仍为单相CaCu5型结构,但合金相的成分和结构均匀性得到明显改善。金相观察和能谱分析显示,铸态合金为比较粗大的树枝晶结构并存在明显的成分偏析,而快凝合金呈细小的胞状晶结构,合金中元素的分布趋于均匀化。电化学测试表明,快速凝固处理后合金的活化性能不变,循环稳定性得到显著改善,但其放电容量和高倍率放电性能有所降低。研究发现,快凝合金电极的交换电流密度I0以及氢在合金中的扩散系数D较铸态合金有所减小是导致其高倍率放电性能降低的主要原因。快速凝固处理导致无Co合金电化学性能的变化与合金的微结构的改变有关。In this work, the microstructure and electrochemical properties of Co-free MlNi(4.0)Al(0.3)Si(0.1)Fe(0.6) hydrogen storage electrode alloys prepared by both conventional casting and melt-spinning processes at different solidification rate were studied comparatively. XRD analyses indicated that both as-cast and melt-spun alloys were of the CaCu5-type structure single phase, but the crystal lizability and homogeneity of the melt-spun alloys were improved. The optical microscope and EDS analyses showed that the melt-spun alloys had a fine cellular structure and a more homogeneous composition than that of the as-cast alloy which had a coarse dendrite structure with noticeable composition segregation. The electrochemical tests indicated that the melt-spun alloys showed a good activation property and much better cycling stability, but lower discharge capacity and high-rate dischargeability. It is found that the decrease in both exchange current density 10 and the diffusion coefficient D of hydrogen in alloy bulk is the main reason for the degraded HRD of melt-spun alloys. The change of electrochemical properties of the alloy treated by rapid solidification process is related to the microstructure of the alloy.

关 键 词：贮氢电极合金 无钴合金 快速凝固 微观结构 电化学性能 

分 类 号：TG139.7[一般工业技术—材料科学与工程]