Inconel 718 alloy samples were fabricated by selective laser melting (SLM). Microstructure and precipitation in solution-heat-treated- and double-aging-SLM-made Inconel 718 were studied by scanning and transmission electron microscopy. Electron microscope observations showed that disc-shaped and cuboidal γ″, and circular γ′ precipitates with an average size of 10–50 nm developed within cellular γ austenite matrix. The simulated, experimentally observed electron diffraction patterns, and dark-field imaging further revealed that the precipitation of three variants of γ″ in the γ matrix occurred. The coarser acicular γ″, and globular as well as plate-like δ phases precipitated at grain boundaries and also within the interior of austenite matrix. The morphology, distribution and crystallography of these precipitates and their formation mechanisms were analyzed and discussed.
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This is a manuscript of an article published as Cao, G. H., T. Y. Sun, C. H. Wang, Xing Li, M. Liu, Z. X. Zhang, P. F. Hu, A. M. Russell, R. Schneider, D. Gerthsen, Z. J. Zhou, C. P. Li, and G. F. Chen. "Investigations of γ′, γ ″and δ precipitates in heat-treated Inconel 718 alloy fabricated by selective laser melting." Materials Characterization 136 (2018): 398-406. DOI: 10.1016/j.matchar.2018.01.006. Posted with permission.