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

SCRIPTA MATERIALIA

卷:194

Article

Chandra, Shubham¹  Tan, Xipeng¹  Narayan, R. Lakshmi²  Descoins, Marion³  Mangelinck, Dominique³  Tor, Shu Beng¹  Liu, Erjia¹  Seet, Gerald¹ 

[1] Nanyang Technol Univ, Singapore Ctr 3D Printing, Sch Mech & Aerosp Engn, 50 Nanyang Ave, Singapore 639798, Singapore

[2] Indian Inst Technol, Dept Mat Sci & Engn, New Delhi 110016, India

[3] Univ Aix Marseille, IM2NP, UMR 7334 CNRS, F-13397 Marseille 20, France

关键词: Additive manufacturing;    Electron beam melting;    Superalloy;    Nano-scale;    Precipitation;   

DOI  :  10.1016/j.scriptamat.2020.113661

来源: Elsevier

【 摘 要 】

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. gamma' 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. gamma' precipitates, similar to 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. gamma' 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. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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