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

Accepted version
Peer-reviewed

Repository DOI


Type

Article

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Authors

Divya, VD 
Muñoz-Moreno, R 
Messé, OMDM 
Barnard, JS 
Baker, S 

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 < 100 > 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.

Description

Keywords

Nickel-based superalloys, Laser processing, Additive manufacture, Microstructure, Texture, Electron microscopy

Journal Title

Materials Characterization

Conference Name

Journal ISSN

1044-5803
1873-4189

Volume Title

114

Publisher

Elsevier BV
Sponsorship
European Commission (619993)
The authors acknowledge funding from the EU under the Seventh Framework Programme (FP7) through the ASLAM project (CfP topic number: JTI-CS-2013-01-SAGE-06-006Project reference number: 619993). The authors would also like to acknowledge Rolls-Royce plc. for providing conventionally cast CM247LC.