Dissimilar laser cladding of Inconel 718 powder on A-286 substrate: Microstructural evolution

In this work, laser cladding of a Ni-based superalloy powder (Inconel 718) on a Fe-based superalloy (A-286) substrate was performed. The microstructural evolution was studied by optical and electron microscopy techniques, aided by energy dispersive spectroscopy. Additionally, the microhardness along the as-deposited parts was analyzed and correlated with the observed microstructure. It was found that other than austenitic dendrites, Nb-rich carbides, interdendritic Laves networks, and Ti (C, N) were formed; the latter was aided by the presence of pre-existing TiC particles in the substrate. Additionally, a slag oxide layer was seen on the clad surface of the fusion zone. The formation mechanisms of an unmixed zone in the shape of beach and peninsula are discussed.