Refining effect of melt overheating treatment on γ′ phase in ni-based single crystal superalloy

Using microscope and scanning electron microscopy, the effect of melt overheating treatment on the size and morphology of γ′ phase in Ni-based single crystal superalloy is studied in this paper. The results show that as the melt overheating temperature increases from 1500°C to 1640°Cand 1780°C, the primary arm spacing decreases from 177 μm to 150 μm and 125 μm respectively. Meanwhile, Ti enrichment in the interdendrite area and W segregation are all decreased. It can be seen that γ′ phase in both dendrite trunk and interdendrite area are all refined while the morphology of γ′ phase in interdendrite area become cubic. The calculation result shows that the γ-γ′ mismatches both in dendritic trunk and interdendrite area are all gradually decreased.