Phase stability of Fe23Zr6 and thermodynamic reassessment of Fe–Zr system

Abstract

The stability of the Fe23Zr6 phase in Fe–Zr system was studied, and the partial Fe–Zr phase diagram was revised by means of X-ray diffraction, electron probe microanalysis and differential thermal analysis methods. On the basis of the experimental results in the present work and literature, the Fe–Zr system was reassessed using CALculation of PHAse Diagram (CALPHAD) method. Solution phases, liquid, fcc, bcc and hcp, are modeled as the substitutional solution. The intermetallic compounds, hex.-Fe2Zr, Fe2Zr, FeZr2 and FeZr3 phases, are treated as Fe2(Fe, Zr)1, (Fe, Zr)2(Fe, Zr)1, (Fe, Zr)1Zr2 and (Fe, Zr)1(Fe, Zr)3 by a two-sublattice model, respectively. The Fe23Zr6 phase is treated as stoichiometric compound. A set of self-consistent thermodynamic parameters of the Fe–Zr system was obtained. The results confirm the stability of Fe23Zr6 phase, improve the phase diagram of the Fe–Zr system and provide a theoretical reference for the development of Zr alloys.