Microstructural Analysis and Modelling for an additively manufactured Nickel-Based superalloy for Gas Turbine applications

The aim of this thesis is to investigate the relationships between process parameters, microstructure, and defect formation in a Ni-based superalloy produced by Laser Powder Bed Fusion (LPBF). Particular attention was given to the quantitative analysis of melt pool geometry, porosity, and grain morphology, using optical and electron microscopy. Results showed that volumetric energy density (VED) is the most reliable parameter to describe melt pool geometry, with higher VED leading to deeper and narrower pools, while models based solely on laser power or linear energy density proved inadequate. Porosity analysis highlighted a higher susceptibility in thin-wall samples, whereas post-processing heat treatments reduced defects and promoted more homogeneous equiaxed microstructures. Overall, this work provides a methodological framework for the predictive control of melt pool stability and for the optimization of LPBF processes, supporting the development of advanced superalloy components for high-performance applications.