Epitaxial deposition of nickel-based superalloy René 142 through scanning laser epitaxy (SLE)

Abstract

Single-pass depositions of columnar René 142 on investment cast single-crystal (SX) René N5 substrates having [100] and [001] primary dendrite growth directions were obtained through scanning laser epitaxy (SLE), a laser powder bed fusion (LPBF)-based additive manufacturing (AM) process. The microstructure and the microhardness properties of the René 142 deposits were investigated through high-resolution optical microscopy (HR-OM), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD), electron backscatter diffraction (EBSD), and micro-hardness measurements. HR-OM investigations revealed the capability of SLE in depositing more than 1000 μm of columnar René 142 in a single pass. SEM investigations demonstrated that the primary γ/γ′ precipitates in the deposit region were 90% finer in size compared to the substrate. XRD investigation revealed the presence of a strong [200] peak and EBSD analysis confirmed SX René 142 growth. Microhardness measurements showed an increase in the hardness values by ∼10% in the deposit region compared to the cast substrate. The results showed that the SLE process has tremendous potential in producing epitaxial deposits of nickel-based superalloys and, therefore, the findings reported in this work can pave ways to fabricate components with dissimilar-chemistry high-γ′ nickel-based superalloys using an LPBF-based AM process.