Comparison of Microstructures and Properties for a Ni-Base Superalloy (Alloy 625) Fabricated by Electron Beam Melting

Nickel-based superalloys processed by additive manufacturing have demonstrated directional solidification, which has been shown to equal or improve mechanical properties compared to cast and wrought alloys. Inconel 625 cylinders have been manufactured by electron beam melting (EBM) and selective laser melting (SLM) and compared. EBM cylinders were built in the Z-axis direction (parallel to the build direction), and SLM cylinders were built in XY-axis (perpendicular to build direction) and Z-axis directions. The microstructures of as-fabricated as well as fabricated and HIPed cylinders were characterized by light optical metallography (LOM), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive (X-ray) spectroscopy (EDS). EBM fabricated components contained columnar plates of ?¢¢ (Ni3Nb) precipitates while SLM components contained columnar arrays of fine ?¢¢ nanoparticles. The EBM fabricated and HIPed samples and SLM fabricated and HIPed samples exhibited equiaxed grains, but both components contained complex arrays of dissimilar precipitates.