Effect of heat treatment on the microstructures of CMSX-4^® processed through scanning laser epitaxy (SLE)

Engineered components made of superalloys routinely undergo heat treatment procedures to tailor their microstructures and properties. In this study, the effect of heat treatment on the microstructures and microhardness of single-crystal nickel-base superalloy CMSX-4^® is investigated. Samples of CMSX-4^® are fabricated using scanning laser epitaxy (SLE), a laser powder bed fusion (LPBF)-based additive manufacturing process. Microstructural characterizations of the as-deposited and the heat treated CMSX-4^® samples are performed using optical microscopy, scanning electron microscopy, x-ray diffraction, and Vickers microhardness measurements. The results show that the microstructure is homogenized with reductions in the eutectic volume fraction after heat treatment. The microhardness values are also improved upon heat treatment. This work is sponsored by the Office of Naval Research through grant N00014-14-1-0658.