Microstructure of selective laser melted CM247LC nickel-based superalloy and its evolution through heat treatment

By V. Divya, R. Muñoz-Moreno, O. Messé, J. Barnard, S. Baker, T. Illston, Howard J. Stone. 2016

240 citations recorded by the source corpus.

Abstract The selective laser melting of high temperature alloys is of great interest to the aerospace industry as it offers the prospect of producing more complex geometries than can be achieved with other manufacturing methods. In this study, the microstructure of the nickel-based superalloy, CM247LC, has been characterised following selective laser melting and after a post deposition heat treatment below the γʹ solvus temperature. In the as-deposited state, scanning electron microscopy with electron backscatter diffraction revealed a fine, cellular microstructure with preferential alignment of 〈001〉 along the build direction. A high dislocation density was seen at the periphery of the cells, indicating substantial localised deformation of the material. Fine primary MC carbides were also observed in the inter-cellular regions. High-resolution transmission electron microscopy identified the occurrence of very fine γʹ precipitates, approximately 5 nm in diameter, dispersed within the gamma phase. After heat treatment, the elongated cell colonies were observed to partially coalesce, accompanied by a decrease in dislocation density, producing columnar grains along the build direction. Cuboidal γʹ precipitates approximately 500 nm in diameter were observed to form in the recrystallised grains, accompanied by larger γʹ precipitates on the grain boundaries.

Subfields: Mechanical Engineering, Mechanics of Materials

View Paper: https://www.semanticscholar.org/paper/d41cd35f27ca73144393dbb951095068c6c9790f

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In Mechanical Engineering

In Mechanics of Materials

Citations in the corpus

Improving the fatigue behaviour of a selectively laser melted aluminium alloy: Influence of heat treatment and surface quality (2016, background): “SLM parts can suffer from cracks [16], pores [17], poor surface roughness, and high residual stresses [18] arising from the high energy density {energy density = laser power / (scan speed * hatch spacing * layer thickness) [19]} induced by the process and subsequent fast solidification [20, 21] and ”
Effect of laser rescanning on the grain microstructure of a selective laser melted Al-Mg-Zr alloy (2018, background): “[3] Electron beam melting (EBM) of Ni-based superalloys has resulted in in-situ precipitation [4] but superalloys fabricated with SLM have minimal to no precipitation.[5] This difference in precipitation behavior can be attributed to the high preheat temperatures in the EBM process that leads to in-”