Microstructural evolution of a nickel-base single-crystal superalloy during homogenisation at ultra-high temperature has been investigated using scanning electron microscope and electron probe microanalyzer. The results show that incipient melting occurs and all γ/γ′ eutectics are re-melted into liquid after 1 h homogenisation at 1350°C. The volume fraction of IM decreases gradually with increasing homogenisation time. The IM disappears totally after 14 h homogenisation. Moreover, the formation of the TCP phase is suppressed during long-term thermal exposure at 1100°C for the reduction of element segregation, especially the segregation of refractory element Re was reduced during ultra-high-temperature homogenisation. The microstructure evolution of IM was discussed based on the element diffusion during homogenisation.
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