快淬-退火La_4MgNi_(19)合金的电化学储氢性能及其失效行为  

Electrochemical Hydrogen Storage Performances and Degradation Behavior of Rapid Quenching-Annealed La_4MgNi_(19) Alloy

作　　者：邢磊[1,2] 李一鸣 张羊换 任慧平[1,2] 金自力 Xing Lei;Li Yiming;Zhang Yanghuan;Ren Huiping;Jin Zili(School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Baotou 014010, China;Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010, China;Analytical and Testing Center, Inner Mongolia University of Science and Technology, Baotou 014010, China)

机构地区：[1]内蒙古科技大学材料与冶金学院,内蒙古包头014010 [2]内蒙古自治区白云鄂博矿多金属资源综合利用重点实验室,内蒙古包头014010 [3]内蒙古科技大学分析测试中心,内蒙古包头014010

出　　处：《稀有金属》2017年第12期1318-1326,共9页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(51371094);内蒙古自然科学基金项目(2014MS0526)资助

摘　　要：利用快淬法制备了La_4MgNi_(19)储氢合金,并对快淬合金进行了退火处理,对比研究了快淬及其退火合金组织结构、储氢性能的差异,并对其失效行为进行了分析。结果表明,快淬La_4MgNi_(19)合金由(La,Mg)_2Ni_7,(La,Mg)_5Ni_(19)和LaNi_5多相组成,退火使晶粒尺寸变大并促进了(La,Mg)_5Ni_(19)相含量的增加。退火处理提高了快淬合金的最大放电容量和高倍率放电性能,但降低了合金的电化学循环稳定性。浸泡试验表明退火能够提高合金的本征耐腐蚀性。然而气态吸放氢循环实验后的粒度分析发现退火加剧了合金的粉化。快淬合金具有优异的抗粉化能力,在30次气态循环实验中合金粒度几乎不变,这是快淬合金电化学循环稳定性更好的主要原因。透射电镜(TEM)分析表明退火合金粉化加剧的原因在于退火过程中形成了大量的显微台阶,显微台阶之间的结合较弱,容易开裂;此外,退火过程中合金发生了部分氧化,在晶界处引入了氧化物质点,弱化了晶界的结合力。La4MgNi19 hydrogen storage alloys were prepared by rapid quenching and then followed by annealing. Microstructure and hydrogen storage performances of the as-quenched and annealed alloy were studied, and the degradation behaviors were analyzed in the present work. It showed that the as-quenched alloy presented multi-phase microstructure composed of （ La, Mg） 2Ni7 , （ La, Mg） 5Ni19 and theLaNi5phases. Grain size and abundance of （La, Mg）5 Ni19 phase were enhanced after annealing. In addition, annealing elevated the discharge capacity and high rate discharge performance, but suppressed the electrochemical cycle stability. The immersion experi- ment illustrated that annealing was beneficial to the intrinsic corrosion resistance of the La4MgNi19 alloy. However, particle size analysis of the gaseous cycled alloys indicated that the anti-pulverization ability was worse after annealing. The as-quenched alloy had excellent anti-pulverization ability whose particle size was ahnost invariant after 30 gaseous hydrogen absorption/desorption cycles, which was believed to be the main reason that gave rise to its better electrochemical cycle stability. Observations under transmission electron microscope （TEM） found that severe pulverization of the annealed alloy was caused by presence of the micro-ledge which was easy to fracture during the hydrogen absorption/desorption cycling. Furthermore, the oxidized particles distributing among the grain boundaries which were brought by oxidation of the alloy in the annealing process, weakened the binding force of grains against the pulverization.

关 键 词：La—Mg—Ni系合金 快淬一退火处理 

分 类 号：TG139.7[一般工业技术—材料科学与工程]