A modified random sampling method using unidirectionally solidified specimen: Solute partition coefficients in Fe–Cr–Ni–Mo–Cu alloys

Abstract

A random sampling method using Fe-19.9 mass% Cr-24.8 mass% Ni-4.5 mass% Mo-1.5 mass% Cu alloy quenched during unidirectional solidification was applied to examine the measurement accuracy of the solute partition coefficients between the solid and liquid phases. Better agreement between the solute profiles obtained by the random sampling and Scheil’s equation was observed at appropriate regions where the solid fraction ranged from 0.9 to 1 at quenching. The partition coefficients of Cr, Ni, Mo, and Cu were determined to be 0.95, 1.01, 0.71, and 0.84, respectively. The values obtained using the present method agreed well with the values measured using the in-situ measurement method, which is recognized to be a reliable technique. The developed technique, which uses conventional equipment and techniques such as a unidirectional solidification furnace and scanning electron microscopy/energy-dispersive X-ray spectroscopy, requires less time to determine the solute partition coefficients than conventionally used techniques. Thus, the modified random sampling method presented in this study can be used for systematic measurements of solute partition coefficients.