合金凝固组织对氢扩散和MH电极性能的影响

用电位阶跃法和恒电流充放电法研究了贮氢合金凝固组织中的氢扩散行为和合金氢化物（ＭＨ）电极放电的速度特性．研究表明：合金ＭＬＮｉ３．４５（ＣｏＭｎＴｉ）１．５５的各凝固组织中氢扩散系数及合金的电极性能均明显不同，随合金凝固时冷却速度增大，氢扩散系数和晶胞体积减小；合金电极的高倍率放电率主要取决于氢在合金中的扩散速度和电极表面的电催化活性．定向凝固组织具有良好的放电速度特性与其凝固组织中存在Ｎｉ的析出相关系密切．

The influence of solidified AB_5 type alloy microstructure on the diffusion of H atom and the properties of metal hydride electrodes

Diffusion behavior of H atom in the solidified microstructure of alloy MLNi3.45(CoMnTi )1.55 is investigated by using electrochemical potential-step method and the discharge rate characteristies of the metal hydride electrodes is inyestigated by galvanostaticcharge/discharge. The investigation shows that diffusion coefficient of H atom and the properties of the metal hydride electrodes are remarkably different for different solidified microstructures. The cell volume of alloys and the diffusion coefficent of H atom decrease withthe increase of cooling rate of alloy's solidification. The high discharge rate of the electrodesdepends mainly on the diffusion kinetics of H atom in the alloys and electrocatalytic activityof the electrodes surface. A good discharge rate behavior of unidirectionally solidified microstructure is closely related to the precipitation of Ni phase in the solidified microstructure.