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Elemental Sub-Lattice Occupation and Microstructural Evolution in γ/γ′ Co–12Ti–4Mo–Cr Alloys

Published online by Cambridge University Press:  23 April 2021

Hye Ji Im
Affiliation:
Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
Surendra K. Makineni
Affiliation:
Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, India
Chang-Seok Oh
Affiliation:
Korea Institute of Materials Science, Changwon 51508, Republic of Korea
Baptiste Gault
Affiliation:
Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany Department of Materials, Royal School of Mines, Imperial College, Prince Consort Road, London SW7 2BP, UK
Pyuck-Pa Choi*
Affiliation:
Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
*
*Author for correspondence: Pyuck-Pa Choi, E-mail: p.choi@kaist.ac.kr

Abstract

We report on comparative atom probe tomography investigations of γ/γ′-forming Co–12Ti–4Mo–Cr alloys. Moderate additions of Cr (2 and 4 at%) reduced the γ/γ′ lattice misfit and increased the γ′ volume fraction of a Co–12Ti–4Mo alloy significantly. These microstructural changes were accompanied by changes in the elemental partitioning between γ and γ′ and site-occupancy in γ′. Spatial distribution maps revealed that Mo occupied both Co and Ti sub-lattice sites in γ′. In agreement with the experimental data, thermodynamic calculations predicted a stronger tendency for Mo to occupy the Co-sites than for Cr and an increase in Cr fraction on the Ti-sites with increasing Cr content.

Type
Applications in Alloys
Copyright
Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of the Microscopy Society of America

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Elemental Sub-Lattice Occupation and Microstructural Evolution in γ/γ′ Co–12Ti–4Mo–Cr Alloys
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