Isothermal Sections (400 and 550 °C) of the Phase Diagram of the La—Ni—Fe Ternary System.

Abstract

Abstract The 400 and 550 °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 °C isothermal section was restricted to the Fe- and La-rich parts of the La–Ni–Fe ternary system. The 550 °C isothermal section was restricted to the Fe- and Ni-rich parts of the La–Ni–Fe ternary system. The (partial) 400 °C isothermal section consists of four single-phase regions, five two-phase regions and two three-phase regions. The (partial) 550 °C isothermal section consists of eight single-phase regions, thirteen two-phase regions and six three-phase regions. At 550 °C, the maximum solid solubility of Ni in Fe is about 5 at.% Ni; the maximum solid solubilities of Fe in Ni, LaNi 5 , La 2 Ni 7 , LaNi 3 , La 7 Ni 16 , La 2 Ni 3 , and LaNi are about 75.5, 10, 5, 4, 1.5, 3 and 2 at.% Fe, respectively. The solubility of La in α-Fe and β-Ni is about 1.5 at.% La and 2 at.% La, respectively.