Experimental Investigation and Thermodynamic Reassessment of the Cu-Fe-Si System

Based on a critical evaluation of experimental data available in the literature, the isothermal section at 1023 K of the Cu-Fe-Si system was measured using a combination of X-ray analysis, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analysis, and electroprobe microanalysis (EPMA). In addition, fifteen alloys along two vertical sections at 30 and 70 at. pct Cu were subjected to differential thermal analysis (DTA), in order to provide new phase-transition temperatures. A thermodynamic modeling for the Cu-Fe-Si system was then conducted by considering reliable experimental data from the literature and the present work. All the calculated phase equilibria and thermodynamic properties agree well with the experimental ones. It is noteworthy that a stable liquid miscibility gap appears in the computed ternary phase diagrams, even though it is metastable in the three-boundary binaries. Significant improvements have been made compared with the previous assessments. The presently obtained parameters were also successfully applied to two technical cases in material design.