Experimental Determination of Phase Equilibria in Fe-Cr-Ni-Al System

Alloys Fe-18Cr-9Ni-3Al, Fe-16Cr-18Ni-5Al, and Fe-20Cr-20Ni-5Al wt.% were prepared by vacuum arc melting and heat treated at 600 °C/514 days, 800 °C/56 days, 1000 °C/32 days, and 1100 °C/15 days. The microstructures of the samples were characterized to identify the equilibrium phases at each temperature. The compositions of the phases were measured with SEM-EDS. Solidus and liquidus were determined using DSC. The experimental results were compared with equilibrium thermodynamic calculations. Significant differences were observed for solidus, solvus temperatures, and compositions of the equilibrium phases.