快淬AB_5型稀土储氢合金的微结构与电化学性能

Microstructures and Electrochemical Properties of AB_5-type Rare Earth Hydrogen Storage Alloys Prepared by Rapid Quenching

采用磁悬浮感应熔炼法和快淬法制备了Mm0.3Ml0.7Ni3.55Co0.75Mn0.4Al0.3稀土储氢合金,系统研究了快淬速度对合金微结构和电化学性能的影响.X射线衍射(XRD)及扫描电镜(SEM)分析表明,快淬态合金中出现了新相LaNi3和La2Ni3,且LaNi3和La2Ni3相含量随快淬速度的增大而增大.电化学性能测试表明,合金的放电特性和最大放电容量随快淬速度的增大呈现出先变好后变坏的变化规律,15m/s快淬态合金的放电特性和最大放电容量达到最佳.此外,恰当的快淬速度能明显改善合金的循环稳定性.

The as-cast and rapidly quenched Mm0.3Ml0.7Ni3.55Co0.75Mn0.4Al0.3 hydrogen storage alloys were prepared by induction melting with the magnetic levitation and rapidly quenching technique,and the effects of the quenching rate on microstructures and electrochemical properties of the alloys were investigated systematically.XRD and SEM analysis showed that the LaNi3and La2Ni3new phases appeared in quenched alloys.The content of LaNi3 and La2Ni3phases in the alloy increased with increasing quenching rate.Electrochemical tests showed that the discharge potential characteristic and the maximum discharge capacity were improved firstly and then degenerated with increasing quenching rate.Among the alloy samples studied,the above properties of the quenched alloys at 15 m/s were the best.Furthermore,an appropriate quenching rate obviously enhanced the cycle stability of the alloys.