Investigation of phase equilibria in the Ce-Co-Fe system during solidification

Phase transformations in the Ce-Co-Fe ternary system have been studied using DTA, X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). No ternary compounds have been identified in this system. Liquidus and solidus projections and a Scheil diagram for solidification were constructed. At the solidus temperatures two continuous solid solutions form: (1) between isostoichiometric compounds Ce2Fe17 (Zn17Th2-type structure, hR57-R-3m) and Ce17Co2 (Th2Ni17-type structure, hP38-P6(3)/mmc) and (2) between the Laves phases CeFe2 and CeCo2 (MgCu2-type structure, cF24-Fd-3m). Among the binary system-based phases, CeCo3 has the widest homogeneity region and dissolves up to 58 at% Fe at the solidus temperature. The homogeneity regions of the remaining phases are smaller. Five three-phase fields in the solidus surface result from four transition type and one eutectic invariant four-phase equilibria. (C) 2017 Elsevier B.V. All rights reserved.