Microstructure and nanoindentation creep behavior of IC10 directionally solidified superalloy repaired by laser metal deposition

Highlights: • The microstructure and nanoindentation creep behavior of IC10 alloy repaired by laser metal deposition are studied. • The microstructures are different in different zones (substrate, HAZ, deposited layers) of the repaired alloy. • The creep resistances of different zones are different, and the dominant creep mechanism is dislocation movement. • The bottom zone of the deposition layers presents fine microstructure, high hardness, and superior creep property. In this study, the microstructure and nanoindentation creep behavior of IC10 directionally solidified superalloy repaired by laser surface re-melting combined with quasi-continuous-wave laser metal deposition were investigated in detail. It is found that the primary dendritic arm spacing in the deposition layers is far smaller than that in the substrate (400 μm). Along the deposition height direction, the primary dendritic arm spacing increases from 4.27 to 5.46 μm due to the decreases of cooling rate. The average size of γ′ phases and carbides in deposition layers are also smaller than those in the substrate. Due to the high cooling rate, the average size of pores in bottom zone of deposition layers is larger than that in the middle and top zones. However, it is smaller than that in the substrate. The nanoindentation hardness and creep resistance of deposition layers are superior to those of the substrate and heat affected zone. The dominant creep mechanism of repaired alloy is dislocation movement. The bottom zone of deposition layers presents the fine microstructure, superior nanoindentation hardness and creep properties. These findings could provide technical support in achieving the consistency of microstructure and properties during repairing and additive manufacturing the directionally solidified superalloys.