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.