机械合金化LaNi5-26wt%Mg合金的结构及性能研究

采用X -射线衍射仪 (XRD)、扫描电子显微镜 (SEM)、差热分析仪 (DTA)及电池性能测试仪等研究了机械合金化及热处理等工艺因素对LaNi5 2 6wt%Mg合金的组织形貌、热稳定性及电化学贮氢性能等的影响。结果表明 :经 2 80r/min机械合金化 2 5 0h后 ,样品由镧、镁、镍等非晶和MgNi2 纳米晶(3 1nm)组成 ,颗粒形状为规则的球形或近球形 ,粒径为 0 0 6～ 12 6μm ,其中约有 95 %的颗粒的粒径为0 5～ 2 0 μm。该样品经首次充放电活化时即达到其最大的放电容量 (4 2 0mAh/g) ,具有较好的室温电化学活化特性。经 763K保温 3 5d ,样品由热稳定性较好的具有纳米尺度 (2 4 1nm)的Mg2 NiLa、Mg2 Ni、MgNi2 三相组成。

STRUCTURE AND PROPERTIES OF LaNi5-26wt%Mg ALLOY PREPARED BY MECHANICAL ALLOYING

The influence of technological factors,such as mechanical alloying and heat treatment,on microstructure and structural characteristics,thermal stability and electro-chemical properties of LaNi 5-26 wt %Mg alloy synthesized by mechanical alloying were investigated by X-ray diffraction(XRD),scanning electron microscope(SEM),differential thermal analysis(DTA)and battery test apparatus in this paper The results showed that amorphous and nanocrystalline structure can be obtained in the alloy after mechanical alloying for 250h at 280r/min,and the shape of the particles were sphere or spheroid,the size of particles were 0 06～12 6μm,and 95% of particles were 0 5～2 0μm The specimen reached its maximum discharge capacity(420mAh·g -1 )after the first charge/discharge cycling at ambient temperature After heat treatment for 35d at 763K,the alloy was stable and consisted of Mg 2NiLa,Mg 2Ni and MgNi 2 phases with the average grain size of 24 1nm