Formation mechanism and stability of austenitic islands in carbides in a Ni-Cr-Fe based high-temperature austenitic alloy undergoing carburization

SCRIPTA MATERIALIA

卷:197

Article

Shu, Shipeng¹  Hu, Xiaobing¹  Kazemzadeh-Atoufi, Maryam¹  Liu, Tao^1,2  Shang, Anyu¹  Davis, Mark B.⁴  Ziebarth, Robin⁵  Dhingra, Sandeep⁵  Morgan, Robert D.⁵  Du, Yao⁴  Voorhees, Peter W.¹  Seidman, David N.^1,3 

[1] Northwestern Univ, Dept Mat Sci & Engn, 2220 Campus Dr, Evanston, IL 60208 USA

[2] Chongqing Univ, Coll Mat Sci & Engn, Chongqing 400044, Peoples R China

[3] Northwestern Univ, Ctr Atom Probe Tomog, 2220 Campus Dr, Evanston, IL 60208 USA

[4] Dow Chem Co USA, Freeport, TX 77541 USA

[5] Dow Chem Co USA, Midland, MI 48674 USA

关键词: High-temperature alloys;    Phase transformation;    Analytical electron microscopy;    Atom-probe tomography;    Dual-beam FIB tomography;   

DOI  :  10.1016/j.scriptamat.2021.113792

来源: Elsevier

【 摘 要 】

We investigate a phase transformation in a Ni-Cr-Fe-based high-temperature alloy during the technologically important carburization process, with multi-length scale experimental techniques. The study focuses on the formation and stability of novel austenitic islands formed within carbide structures during the M23C6 to M7C3 phase-transformation. We demonstrate that the austenitic islands nucleate near the M23C6/M7C3 transformation front, from a supersaturation of metal atoms in the M23C6-carbide as M7C3 grows. After formation, the austenitic islands equilibrate their composition with the matrix temporally but remain relatively stable inside the carbides due to their large sizes (a few hundred nanometers in diameter) and a weak Gibbs-Thomson effect. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

【 授权许可】

Free