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

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 mu m). Along the deposition height direction, the primary dendritic arm spacing increases from 4.27 to 5.46 mu m due to the decreases of cooling rate. The average size of gamma' 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.

Automated summary

The study found that repairing IC10 directionally solidified superalloy using laser surface re-melting combined with quasi-continuous-wave laser metal deposition results in finer microstructure, superior hardness, and creep resistance in the deposition layers, with the bottom zone exhibiting the best properties.