为了研究不同退火方式对La_(0.75)Mg_(0.25)Ni_(3.44)Co_(0.2)Al_(0.03)Ti_(0.03)铸态合金的电化学性能影响,设计最终退火温度为1223K,并采用不同保温程序对合金进行退火处理.X射线衍射(XRD)与扫描电镜(SEM)分析一段、两段保温法退火后合金的结构与性能结果表明,铸态及退火后合金由LaNi_5,(La,Mg)_2(Ni,Co,Al)_7相以及少量LaNi_2、TiNi_3相组成,且退火后合金中(La,Mg)(Ni,co,Al),相出现.前者微观组织较后者均匀,并且前者的放电容量、放电效率好于后者.一段保温法更有利于改善合金的循环稳定性.
In order to investigate the effect of different annealing way on electrochemical property of the as-cast La_(0.75)Mg_(0.25)Ni_(3.44)Co_(0.2)Al_(0.03)Ti_(0.03) alloy, the alloy was annealed at 1223K by one-step and two-step holding temperature process, respectively. The microstructure and property of the annealed alloy were examined by XRD and SEM. The results show that the microstructue of the as-cast alloy is composed of LaNi_5, (La, Mg) _2 (Ni, Co, Al) _7 phase and a small amount of LaNi_2, TiNi_3 phases. After annealing, the TiNi_3 phase disappears and(La, Mg) (Ni,Co,Al) _3 phase appears in the annealed alloy. The microstructure of the alloy annealed by one-step holding temperature process is more homogeneous compared with that annealed by two-step holding temperature process. Meantime, the discharge capacity and discharge efficiency of the former is higher than that of the latter. Annealing treatment of one-step holding temperature process is more favorable for improving the cycling stability of the alloy than two-step holding temperature process.
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