The 400℃ Isothermal Sections Of The Phase Diagram Of The La-Ni-Nb Ternary System And The Electrochemical Property Of LaNi_-5xNb_x Alloy

1.The 400 C isothermal section of the La-Ni-Nb ternary systemThe 400 isothermal sections of the phase diagram of the La-Ni-Nb ternary system has been investigated by powder X-ray diffraction (XRD),differential thermal analysis (DTA), optical microscopy (OM) and scanningelectron microscopy(SEM) techniques.The 400 C isothermal section of the phase diagram of the La-Ni-Nb ternary system consists of 14 single-phase regions, 25 two-phase regions and 12 three-phase regions.At 400 C, the maximum solid solubilities of Nb in Ni, LaNi5, La2Ni7, LaNi3, La7Ni16, and La2Ni3 is about 3, 5, 2, 3, 3, and 2 at. % Nb, respectively.The composition range of the Nb in NbNi3 is about from 23.5at.% Nb to 27at.% Nb. No ternary compounds were observed.2. The electrochemical property of LaNi5-xNbx electrode alloysApart from the phase diagram of La-Ni-Nb system, the electrochemical property of LaNi5-xNbx has also been investigated. The open recycling batteries were made with LaNi5-xNbx cathode and Ni(OH)2 anode in the electrolyte of 6mol/L KOH. By analyzing the experiment results from the automatic charger-discharger - DC-5 battery testing instrument, we found that the little substitution of Nb for Ni in LaNi5 could improve the property of activation.