Experimental determination of interaction coefficients of components in ternary Si-Fe-Al alloy solution

The “same activity” method was used to determine the activity interaction coefficient of Al to Fe in a Si-based solution. Al was dissolved into a binary Si-Fe solution at 1663, 1673, 1693 and 1723 K. The solubility of Fe and Al in silicon was determined at different temperatures, and the interaction coefficients of Al to Fe were calculated and obtained by fitting the solubility data of Al and Fe. Scanning Electron Microscopy-Energy Dispersive Spectrometer (SEM-EDS) and Electron Probe Micro Analyzer (EPMA) techniques were used to verify the uniformity of the Si-Fe-Al alloy samples and the reliability of the interaction coefficient obtained by experiments at 1693 and 1723 K. The X-ray Powder Diffraction (XRD) results displayed the phase transformation from FeAl3Si2 to FeAl2.7Si2.3 to Fe3Al0.3Si0.7 with rising dissolution temperature, and crystallographic data of the phases were obtained by Rietveld refinements.