Segregation of niobium and aluminum in GH783 alloy ingots

Investigation was made on the segregations of Nb and Al elements in GH783 alloy consumable electrode by means of SEM examination and EDX analysis. Nb-enriched eutectic was generally observed between the dendrites within the casting grains of the GH783 alloy ingot, and can be eliminated completely by long time homogenization treatment at temperature of about 1180 °C. Al-enriched β phase was found along grain boundaries in the samples of the consumable electrode before and after homogenization treatment, and its amount was largely dependent on cooling rate of the alloy from high temperature. It was concluded that the precipitation of β phase along grain boundaries was related to the segregation of aluminum atoms at grain boundaries during cooling of the alloy from high temperature. Analysis was made on both the occurrence of eutectic reaction between dendrites in the grains during solidification and the precipitation of Al-enriched β phase along grain boundaries when the alloy cooling from high temperature.