Nanometer-scale precipitations in a selective electron beam melted nickel-based superalloy

Shubham Chandra (1) , Xipeng Tan (1) , R. Lakshmi Narayan (2) , Marion Descoins (3) , Dominique Mangelinck (3) , Shu Beng Tor (1) , Erjia Liu (1) , Gerald Seet (1)

1 School of Mechanical and Aerospace Engineering [Singapore]
2 IIT Delhi - Indian Institute of Technology Delhi
3 IM2NP - Institut des Matériaux, de Microélectronique et des Nanosciences de Provence

The nanometer-scale (nano-scale) microstructural evolution in an additively manufactured Re-free Ni-based superalloy, with single crystal compositions, is investigated through field emission scanning electron microscopy, transmission electron microscopy, and atom probe tomography. We find that nano-scale primary γ′ precipitation occurs in the fine as-built microstructure, leading to an exceptional microhardness of 480.0 ± 6.7 HV at room temperature. Presence of ultra-fine γ′ precipitates, ~ 20 nm in size, is observed in the bottom few layers of the as-built samples, which is hitherto undocumented and contrary to the widespread consensus regarding hierarchical γ′ phase evolution in additively manufactured Ni-based superalloys. Moreover, considerable precipitation of tantalum-rich C14 Laves phase at the grain boundaries and interdendritic regions in the as-built samples emphasizes the need for additive manufacturing specific alloy design.

Mots clés: Additive manufacturing; Electron beam melting; Superalloy; Nano-scale; Precipitation

Domaines: Matériaux

Shubham Chandra, Xipeng Tan, R. Lakshmi Narayan, Marion Descoins, Dominique Mangelinck, et al.. Nanometer-scale precipitations in a selective electron beam melted nickel-based superalloy. Scripta Materialia, 2021, 194, pp.113661. ⟨10.1016/j.scriptamat.2020.113661⟩. ⟨hal-03454753⟩