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

作者：Divya V D^*; Munoz Moreno R; Messe O M D M; Barnard J S; Baker S; Illston T; Stone H J

来源：Materials Characterization, 2016, 114: 62-74.

DOI：10.1016/j.matchar.2016.02.004

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

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 gamma' 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 gamma' 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 gamma' precipitates approximately 500 nm in diameter were observed to form in the recrystallised grains, accompanied by larger gamma' precipitates on the grain boundaries.

• 出版日期2016-4