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Microstructural evolution during directional solidification (DS) of Ni-base superalloy IN792+Hf has been in- vestigated with an emphasis on theγ′precipitates and MC-type carbides.The quantitative image analyses revealed that the increase in the solidification rate up to 100μm/s at constant thermal gradient of 178 K/cm resulted in a fine and uniform distribution ofγ′precipitates.The relationship between the as-castγ′size and cooling rate was also determined for DS IN792+Hf.In the mean time,the MC carbide size was found to be dependent both on the solidification rate and the S/L interface morphology while the area fraction of MC carbide was significantly influenced by the S/L interface morphology.
Microstructural evolution during directional solidification (DS) of Ni-base superalloy IN792 + Hf has been in- vestigated with an emphasis on the γ’precipitates and MC-type carbides. The quantitative image analysis showed that the increase in the solidification rate up to 100 μm / s at constant thermal gradient of 178 K / cm resulted in a fine and uniform distribution of γ’precipitates. The relationship between the as-castγ’size and cooling rate was also determined for DS IN792 + Hf.In the mean time, the MC carbide size was found to be dependent both on the solidification rate and the S / L interface morphology while the area fraction of MC carbide was significantly influenced by the S / L interface morphology.