Influence of substituting Mo for W on solidification characteristics of Re-containing Ni based single crystal superalloy

The influence of substituting Mo for W on solidification characteristics of Re-containing single crystal superalloy was investigated via experimental analysis and thermodynamic calculation. W-rich single crystal superalloy (Alloy W) and Mo-rich single crystal superalloy (Alloy Mo) both had typical dendritic microstructure, while interdendritic precipitations of Alloy W and Alloy Mo were γ′ phase+γ/γ′ eutectic phases and γ′ phase+NiMo phase, respectively. Meanwhile, W significantly segregated to dendritic region in Alloy W, while Mo segregated to interdendritic region in Alloy Mo. Moreover, substituting Mo for W obviously decreased the microsegregation degree of Re and Al elements. The influence of substituting Mo for W on microsegregation behavior of alloying elements (e.g. Re) effectively decreased the tendency of forming freckle during solidification. Furthermore, substituting Mo for W decreased liquidus temperature and solidus temperature of single crystal superalloy.