Effect of Zr on solidification and microstructure of a Ni-based superalloy with high Al and Ti contents

The total content of Al and Ti in advanced Ni-based wrought superalloys is up to 7.5wt.%, which makes it easier form harmful nonequilibrium eutectic (γ+γ′) η phase. It has been reported that the addition certain amount Zr can modify precipitation phases obviously, but mechanism still controversial. effect ranging from <0.0006wt.% 0.150wt.% on solidification behavior, segregation microstructure a superalloy with high contents was investigated, eliminating interferences C B. Results show increase significantly promotes formation (γ+γ′), Zr-rich phase interdendritic region. Besides phase, dissolves slightly γ′ obviously An interesting phenomenon discovered increases area fraction liquid pools enlarges forming range γ dendrites, suggests markedly retards solidification. affects mainly due retard dissolution them. residual undercooling. serve as element for obvious decreases critical concentration its precipitation.