In-situ measurement of solute partition coefficient in fe-cr-ni-mo alloys by using x-ray imaging and x-ray florescence analysis

This study demonstrates in-situ measurement of solute partition coefficient in multicomponent alloys, using X-ray transmission imaging and X-ray florescence spectroscopy. The developed technique was applied to determine partition coefficients of Cr, Ni and Mo between δ phase and liquid phase in Fe-17.4Cr-12.6Ni-2.0Mo-1.6Mn-0.6Si alloys (mass%). In the observation and measurement, X-ray fluorescence spectra were directly obtained by irradiating the incident X-ray beam (23keV) to the solid phase or the liquid phase near solid/liquid interface. The partition coefficients were simply determined from the X-ray florescence analysis. In addition, successive measurements during unidirectional solidification allowed to measure change in partition coefficient along solidification path. During the solidification, partition coefficients of Cr, Ni and Mo changed from 1.01to 1.08, from 0.76 to 0.70 and from 0.86 to 0.74, respectively. The present study proved that the developed technique was applicable to determine partition coefficients of 3d and 4d transition elements of which characteristic X-ray energies ranged from 4 to 20keV.