Phase Selection and Microstructure Evolution Dependance on Composition for Zr–Fe Eutectic Alloys

Abstract

The knowledge of the phase selection and microstructure evolution of Zr–Fe eutectic alloys is still poorly understood. The presumed eutectic alloy with a nominal composition of Zr_76.0Fe_24.0 was discovered to contain a significant proportion of α-Zr dendrites. Hereby, phase selection and microstructure evolution dependance on composition for Zr–Fe eutectic alloys was experimentally determined by using differential scanning calorimetry (DSC) and meticulous electron microscopes. Eight alloys, spanning the composition range of 73.5–74.7% Zr, were examined to investigate microstructure evolution and non-isothermal crystallization kinetics. Results indicate that in alloys ranging from Zr_73.5Fe_26.5 to Zr_73.9Fe_26.1, the primary FeZr₂ phase demonstrates preferential growth, followed by eutectic microstructure formation during liquid alloy solidification. The volume fraction of FeZr₂ dendrites decreases as the Zr content increases. Conversely, in alloys ranging from Zr_74.0Fe_26.0 to Zr_74.7Fe_25.3, primary β-Zr dendrites preferentially grow, followed by a eutectic reaction in the remaining liquid phase. The content of α-Zr dendrites reduces with decreasing Zr content. As mentioned above, a critical composition range for phase selection is defined as Zr_xFe_100.0−x (73.9 < x < 74.0).