Abstract:The solidification process of cast Ni-base superalloy IN792 was comparatively investigated by differential scanning calorimeter (DSC) and isothermal solidification quenching (ISQ) experiment. The distribution characteristics of elements in solidified solid and residual liquid at different temperatures were also concerned. The isothermal solidification microstructure, the phase precipitation diagram, the solidification characteristic curve and the segregation behavior of elements at different temperatures in liquidus and solidus range were obtained. The results of ISQ indicate that the IN792 alloy possesses a liquidus temperature of 1328 ℃. The onset of MC carbides and eutectic (γ+γ’) formation take place at 1310 and 1225 ℃, respectively. The secondary γ’ is precipitated at 1190 ℃. The macro-solidus temperature determined by DSC was 1250 ℃. The volume fraction of residual liquid at this temperature can reach about 5%. The end of the solidification happened at 1180℃, designated as micro-solidus temperature. No liquid remained at this temperature. There is a 70 ℃ gap between macro and micro-solidus temperature. The hot tearing tends to occur in this temperature range. About 85 vol% solid phase was formed within a range of 30 ℃ below the liquidus temperature. In 1300~1270 ℃ range, the residual liquid in the interdendritic region changed from connected channels to the isolated micro-liquid pools, which is related to the formation of micro-porosity defect. The distribution coefficient of element W and Co are more than 1, indicating that they tend to distribute in solid phase in dendritic region, which are negative segregation elements. The distribution coefficients of element Zr, Mo, Ti, Ta and Cr are less than 1, indicating that they tend to distribute in liquid phase in interdendritic region, which are positive segregation elements. The element Al tends to distribute to liquid phase at the beginning of the solidification, and then be prone to concentrate in the solid phase in the dendritic region and transform to a negative segregation element followed by the solidification temperature decreased. The distribution coefficient of element Al and Ni increases but Mo and Cr decreases followed by the solidification temperature decreasing in 1325~1210 ℃ range. On the contrary, The distribution of element Al and Ni decreases but Mo and Cr increases followed by the solidification temperature decreasing in 1210~1180 ℃ range