Solidification behavior of Ni-base superalloy Udimet 720Li

•We have identified the solidification procedure of the superalloy Udimet 720Li.•We have identified the phases formed during the solidification of superalloy U720Li.•We have discussed the formation mechanism of the γ′/γ eutectic and η phase.

A series of experiments have been conducted to investigate the solidification behavior of Ni-base superalloy Udimet 720Li. The results show that solidification of the alloy proceeds as follows: Liquid (L) → L + γ, L → L + γ + MC-Carbide, L → L + γ/γ′-Eutectic, L → η-phase. The formation of γ/γ′-Eutectic is induced by the rejection of γ′ phase forming elements into the liquid during primary γ phase precipitation. The limited solubility of Ti in primary γ phase and γ/γ′ Eutectic is the main reason that leads to the formation of η-phase. Boride and enrichment of boron have not been detected in the sample. The solidification is terminated by the formation of η-phase. γ′ phase precipitates in the matrix during subsequent cooling.