Influence of Al and Nb on castability of a Ni-base superalloy, IN713LC

Abstract

The influence of Al and Nb on the castability of the Ni-base superalloy, IN713LC, has been experimentally studied. It has been observed that increased Al and Nb additions result in decreased inter-dendritic shrinkage porosity. Porosities were observed in the inter-dendritic channels between abutting secondary dendrite arms within the grain as well as at the grain boundary. For the alloys doped with higher Al and Nb concentration, MC carbides form corresponding to a greater weight fraction liquid. The analysis reveals that the increased fraction liquid for the doped composition improves mush permeability and reduces pressure drop in the inter-dendritic liquid and therefore reduces shrinkage porosity.