Isothermal sections (400 and 550 deg C) of the phase diagram of the La-Ni-Fe ternary System

摘要

The 400 and 550 deg C isothermal sections of the phase diagram of the La-Ni-Fe ternary system were investigated by powder X-ray diffraction (XRD), differential thermal analysis (DTA), optical microscopy and scanning electron microscopy (SEM) techniques. The 400 deg C isothermal section was restricted to the Fe- and La-rich parts of the La-Ni-Fe ternary system. The 550 deg C isothermal section was restricted to the Fe- and Ni-rich pants of the La-Ni-Fe ternary system. The (partial) 400 deg C isothermal section consists of four single-phase regions, five two-phase regions and two three-phase regions. The (partial) 550 deg C isothermal section consists of eight single-phase regions, thirteen two-phase regions and six three-phase regions. At 550 deg C, the maximum solid solubility of Ni in Fe is about 5 at. percent Ni; the maximum solid solubilities of Fe in Ni, LaNi_5, La_2Ni_7, LaNi_3, La_7Ni_(16), La_2Ni_3, and LaNi are about 75.5, 10, 5, 4, 1.5, 3 and 2 at. percent Fe, respectively. The solubility of La in alpha-Fe and beta-Ni is about 1.5 at. percent La and 2 at. percent La, respectively.