Continuous γ′ precipitation in directionally solidified IN738 LC alloy

Abstract

A microstructural characterisation of continuously precipitated γ′ particles in IN738 LC alloy directionally solidified at various cooling rates has been carried out. With decreasing cooling rate there is a trend for the γ′ morphology to vary from rounded particles to irregular cuboids and, finally, a clusterlike formation. In the interdendritic regions, microsegregation leads to an increase in the γ′ solvus temperature, and γ′ precipitation begins at higher temperatures than in the dendrite cores, resulting in differences in particle size and morphology. Observations on the effects of solution treatment and aging on the development of γ′ dispersions are also reported.