Abstract:Directional solidified nickel-base superalloy CMSX-6 specimens were prepared by high rate solidification in VDF-10 directional solidification furnace. Microstructure and tensile properties of the sample in different parts before and after heat treatment were studied respectively. The results show that the former solidified part is denser and primary dendrite arm spacing is narrow, with few eutectic structure and high tensile strength, low elongation. With almost fully homogeneous structure, the alloy no longer shows typical dendritic morphology after heat treatment, significant refinement and homogenization are achieved to γ' phase, and γ/γ' eutectic is dissolved with some homogenization micropores. Tensile strength is slightly improved after heat treatment, but elongation is obviously improved. The fracture mode of specimen is brittle fracture. The cast is of positive break type and the heat treatment state presents shear fracture.