热处理对La_4MgNi_(19)储氢电极合金结构和性能的影响

Effect of Heat Treatment on the Structure and Properties of La_4MgNi_(19) Hydrogen Storage Electrode Alloys

以感应熔炼和不同的热处理工艺制备了La4MgNi19合金,用X射线衍射(XRD)和电化学测试系统研究了该合金的相结构和电化学性能.结构分析表明:当热处理工艺为900°C+水淬时,合金主要由CaCu5结构的LaNi5相和少量未知相组成;当热处理工艺为900°C退火时,合金主要由Pr5Co19、Ce5Co19结构的(La,Mg)5Ni19相及少量CaCu5结构的LaNi5相组成.淬火和退火后合金的电化学循环稳定性(S100)分别为49.7%及76.0%,合金电极的电化学性能和相结构密切相关.退火热处理有利于生成Pr5Co19、Ce5Co19型相.在La-Mg-Ni系储氢合金中,La4MgNi19合金电化学循环稳定性不及La3MgNi14合金.

La4MgNi19 alloys were prepared by induction melting under different heat treatment conditions.Phase structures and electrochemical properties of the alloys were investigated systematically by X-ray diffraction（XRD） and electrochemical experiments.A structural analysis of the alloys showed that all the alloys were composed of multiphases and the alloys obtained after water quenching at 900 ℃ consisted of a main LaNi5 phase and a few unknown phases while the alloys obtained from the annealing treatment at 900 ℃ consisted of Pr5Co19-type,Ce5Co19-type and few LaNi5 phases.The electrochemical cyclic stability（S100） of the water quenched and the anneal-treated alloys was 49.7% and 76.0%,respectively.The cyclic stability of the alloy electrodes was closely related to the phase structures.Annealing treatment was beneficial for the formation of Pr5Co19-type and Ce5Co19-type phases,La4MgNi19 alloys had worse electrochemical cycling stability than the La3MgNi14 alloys from the La-Mg-Ni system＇s hydrogen storage alloys.