La-Mg-Ni系合金循环容量衰减的机理

The cyclic capacity decay mechanism of La-Mg-Ni system alloy

制备铸态及退火后La0.75Mg0.25Ni3.44Co0.2Al0.06合金,以研究La-Mg-Ni系合金的循环容量衰减机理。XRD、SEM和电化学分析表明:合金的主相为(La,Mg)2(Ni,Co,Al)7,还有La(Ni,Co)5和La(Ni,Co)2相。退火合金中各相间Mg和Ni的浓度差降低。铸态合金、950℃和1 050℃退火合金中各相间电化学腐蚀的最大腐蚀电流分别为113.1 mA/g、72.3 mA/g和80.6 mA/g。合金中活性元素氧化腐蚀、合金颗粒粉化以及各相间的电化学腐蚀,是合金电极失效的重要原因。

As-cast and annealed La0.75Mg0.25Ni3.44Co0.2Al0.06 alloys were prepared to investigate cyclic capacity decay mechanism of La-Mg-Ni system alloy.XRD,SEM and electrochemical analyses showed that the main phase of the alloy was（La,Mg）2（Ni,Co,Al）7,it had La（Ni,Co）5 and La（Ni,Co）2 phases too.The concentration differential of Mg and Ni among phases of the alloy decreased after annealing treatment.The maximum corrosion currents of electrochemical corrosion among phases of as-cast alloy and annealed alloys at 950 ℃ and 1 050 ℃ were 113.1 mA/g,72.3 mA/g and 80.6 mA/g,respectively.The oxidation corrosion of active element in alloy,pulverization of alloy particle and electrochemical corrosion among phases were the important reasons led the failure of alloy electrode.