氦在球磨贮氢合金中的存在行为研究

The occupying activities of helium in ball-milled hydrogen-storage alloys

通过正电子寿命测量及结构分析 ,研究了氦气氛球磨LaNi4 .75Al0 .2 5和Zr50 Co50 贮氢合金中氦的存在行为 .研究结果表明 :随着气氛压力增加 ,氦的溶入量增加 ,相对而言 ,LaNi4 .75Al0 .2 5更有利于氦的溶入 ;球磨样品正电子寿命的特征参数发生变化 ,这表明氦在材料中存在行为的差异 ;对于Zr50 Co50 合金 ,氦首先填充在超细晶粒的三叉晶界或空位团处 ,随着气氛压力增加 ,有小部分氦填入单空位的自由体积处 ,形成空位 氦复合体 ;对于LaNi4 .75Al0 .2 5合金 ,氦首先进入单空位大小的自由体积中 ,形成空位 氦复合体 .

Through the measurements of positron lifetime and analysis of structure, the properties of helium in the ball-milled LaNi4.75 Al-0.25 and Zr50Co50 alloys were investigated. It was found that the amount of the injected helium increases with increasing helium pressure. It is comparatively easier for helium to enter the LaNi4.75 Al-0.25 alloy. The difference of the positron lifetime parameters between the above two specimens shows that the properties of the injected helium are different. For Zr50Co50, helium occupies the intersection of two or three crystallite interfaces and/or cluster of vacancies at grain boundaries or groups of vacancies firstly. With increasing pressure of the helium atmosphere, a small amount of helium enters the free volume of single vacancies, and thus vacancy-helium compounds form. For LaNi4.75Al0.25 , helium enters the free volume of single; vacancies and vacancy-helium compounds form.