The analysis of the redistribution of alloy elements during eutectic growth of high chromium cast iron by the use of Thermo-Calc

Abstract

The thermodynamic partition coefficients of Fe-Cr-Mo/V-C quaternary eutectic alloys obtained by numerical simulation were compared to the experimental values. It was found that the partition coefficients of Cr to primary γ, γ+-M7C3 and γ+M3C eutectics are similar to k values of Cr to Fe-Cr-C eutectic alloy, so Mo and V have less influence on the k values of Cr. The thermodynamic k values of Mo to both carbides are less than unit. They decrease as Cr content becomes higher and they are in a good agreement with the experimental results. However, the thermodynamic k values of V are smaller than the experimental ones, and the thermodynamic k values to eutectic are less than unit, though the experimental k values are larger than unit.The redistribution of these elements during eutectic solidification was evaluated by the thermodynamic k values. The distribution of Mo in eutectic carbides and γ agrees well with the experimental results. On the other hand, the distribution of V in eutectic γ and carbides shows different segregation tendency from the experimental result. When the modified database is used, the Thermo-Calc k values and the distribution of V during solidification are close to experimental results.