摘要
采用熔体快淬方法得到了无Co 过化学计量比合金La(NiMn)6的非平衡亚稳单相CaCu5型结构,分析和研究了合金非平衡组织结构和电化学吸放氢性能。X-ray 衍射分析表明,快速凝固合金组织为CaCu5型结构单相组织,与常规熔铸合金比较,快速凝固合金的晶胞参数发生了明显的各向异性变化:随着冷却速度增加,CaCu5 型晶胞a 轴减小,c轴及轴比c/a 增大。电化学实验研究表明,当合金快凝速度≥20 m/s 时,过化学计量比La(NiMn)6合金MH 电极的循环稳定性得到不同程度的改善, 快凝速度≥30 m/s 时,合金电极具有良好的循环稳定性,其最大电化学容量为256 mAh/g^277 mAh/g,循环100 次后合金MH 电极容量保持率为63%～97.8% 。快速凝固合金均大大提高了合金的电化学稳定性,但随着冷却速度增加其活化性能和电极容量有所下降。
Metastable single phase with CaCu5 type structure for Co free over-stoichiometric La(NiMn)(6) alloys were obtained by non-equilibrium processing of melt spinning. The crystal structure and electrochemical properties were investigated comparatively. The XRD results show that the La(NiMn)6 alloys prepared by melt spinning, in comparison with the as-cast alloys, present a single phase with CaCu5 type. The crystal lattice constants a and c exhibit a anisotropic change. With the increase of cooling rate, the a axis decreases and c axis and ratio of c/a value increase. The electrochemical analyses show that when cooling rate increases from 20 m/s to 50 m/s, the MH electrodes discharge capacity reach 277 mAh/g similar to 256 mAh/g and the capacity retention is 63%similar to 97.8% after 100 cycling number. The alloys prepared by melt spinning show a good cycling stability, but a lower discharge capacity and worse activation kinetics than that of the as-cast alloys.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2005年第3期447-451,共5页
Rare Metal Materials and Engineering
基金
甘肃省"十五"科技攻关项目(SZ001-A52-05)
兰州理工大学"特色研究方向资助计划"资助
关键词
非化学计量无钴贮氢合金
快速凝固
晶体结构
电化学性能
Co free hydrogen storage alloys
crystal structure
rapid solidification
electrochemical properties
