Abstract
Purpose. Study of microstructure and phase content of Inconel 718 nickel-chromium-iron superalloy obtained via selective laser melting with subsequent hot isostatic pressing (HIP) and standard heat treatment with high-temperature homogenization and two-steps long term ageing.
 Research methods. Microstructure analysis and phase content investigation was carried out with optical and scanning electronic metallography on optical and electronic microscope respectively.
 Results. Material structure of in-built specimens are investigated that is characterized by layer-by-layer fusing in the form of arcuate lines with a presence of epitaxial growth of columnar dendrites. Strengthening of alloy is achieved after heat treatment, basically, due to intermetallic γ″- phase (with Ni3Nb type) precipitation. With metallographic investigation showed that active segregation of niobium in interdendritic spaces, provided due high crystallization rate during selective laser melting and subsequent heat treatment, lead to forming orthorhombic d- phase in alloy structure with lamellar morphology. HIP application before standard for Inconel 718 heat treatment, promotes more homogeneous structure.
 Scientific novelty. New data’s was obtained for phase state of Inconel 718 alloy after HIP and heat treatment. Fine structure of Ni-Cr-Fe-superalloy obtained via selective laser melting was studied.
 Practical value. Obtained results expands possibilities for Inconel 718 alloy application and allow to determine perspectives of practical usage of selective laser melting process for aviation parts production.
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