Quantitative analysis of sulfur segregation at the oxide/substrate interface in Ni-base single crystal superalloy

Chihiro Tabata; Kyoko Kawagishi; Jun Uzuhashi; Tadakatsu Ohkubo; Kazuhiro Hono; Tadaharu Yokokawa; Hiroshi Harada; Shinsuke Suzuki

doi:10.1016/j.scriptamat.2020.11.003

Quantitative analysis of sulfur segregation at the oxide/substrate interface in Ni-base single crystal superalloy

Chihiro Tabata, Kyoko Kawagishi^*, Jun Uzuhashi, Tadakatsu Ohkubo, Kazuhiro Hono, Tadaharu Yokokawa, Hiroshi Harada, Shinsuke Suzuki

^*Corresponding author for this work

School of Fundamental Science and Engineering

Research output: Contribution to journal › Article › peer-review

8 Citations (Scopus)

Abstract

Oxidation resistance of Ni-base single crystal superalloy is substantially improved when melted using a CaO crucible compared to that melted using an Al₂O₃ crucible. In order to understand the underlying mechanism, sulfur segregation at the oxide/substrate interfaces was characterized using aberration corrected scanning transmission electron microscope with energy dispersive X-ray spectroscopy (STEM-EDS) and three-dimensional atom probe (3DAP). Although sulfur segregation at the interface was detected in both samples, the peak concentration of sulfur was found to be much lower in the sample melted in the CaO crucible, and CaS inclusions were found near the sub-grain boundaries. These experimental results suggest that the improvement in the cyclic oxidation resistance using the CaO crucible is attributed to the suppression of S segregation at the oxide/substrate interface by the trapping of S by dissolved Ca.

Original language	English
Article number	113616
Journal	Scripta Materialia
Volume	194
DOIs	https://doi.org/10.1016/j.scriptamat.2020.11.003
Publication status	Published - 2021 Mar 15

Keywords

3DAP
Nickel
Oxidation
Sulfur segregation
Superalloy

ASJC Scopus subject areas

Materials Science(all)
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering
Metals and Alloys

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10.1016/j.scriptamat.2020.11.003

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title = "Quantitative analysis of sulfur segregation at the oxide/substrate interface in Ni-base single crystal superalloy",

abstract = "Oxidation resistance of Ni-base single crystal superalloy is substantially improved when melted using a CaO crucible compared to that melted using an Al2O3 crucible. In order to understand the underlying mechanism, sulfur segregation at the oxide/substrate interfaces was characterized using aberration corrected scanning transmission electron microscope with energy dispersive X-ray spectroscopy (STEM-EDS) and three-dimensional atom probe (3DAP). Although sulfur segregation at the interface was detected in both samples, the peak concentration of sulfur was found to be much lower in the sample melted in the CaO crucible, and CaS inclusions were found near the sub-grain boundaries. These experimental results suggest that the improvement in the cyclic oxidation resistance using the CaO crucible is attributed to the suppression of S segregation at the oxide/substrate interface by the trapping of S by dissolved Ca.",

keywords = "3DAP, Nickel, Oxidation, Sulfur segregation, Superalloy",

author = "Chihiro Tabata and Kyoko Kawagishi and Jun Uzuhashi and Tadakatsu Ohkubo and Kazuhiro Hono and Tadaharu Yokokawa and Hiroshi Harada and Shinsuke Suzuki",

note = "Funding Information: This research was financially supported by Japan Science and Technology Agency (JST), under the Advanced Low Carbon Technology Research and Development Program (ALCA) “Development of direct and complete recycling method for superalloy turbine airfoils” [grant number JPMJAL1302 ]. The authors would also like to thank Dr. Makoto Osawa and Dr. Yuhi Mori for the helpful discussions, Mr. Yuji Takata for the preparation of the single-crystal superalloys, and Mr. Takuma Kohata for the EPMA analysis. Publisher Copyright: {\textcopyright} 2020",

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month = mar,

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doi = "10.1016/j.scriptamat.2020.11.003",

language = "English",

volume = "194",

journal = "Scripta Materialia",

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T1 - Quantitative analysis of sulfur segregation at the oxide/substrate interface in Ni-base single crystal superalloy

AU - Tabata, Chihiro

AU - Kawagishi, Kyoko

AU - Uzuhashi, Jun

AU - Ohkubo, Tadakatsu

AU - Hono, Kazuhiro

AU - Yokokawa, Tadaharu

AU - Harada, Hiroshi

AU - Suzuki, Shinsuke

N1 - Funding Information: This research was financially supported by Japan Science and Technology Agency (JST), under the Advanced Low Carbon Technology Research and Development Program (ALCA) “Development of direct and complete recycling method for superalloy turbine airfoils” [grant number JPMJAL1302 ]. The authors would also like to thank Dr. Makoto Osawa and Dr. Yuhi Mori for the helpful discussions, Mr. Yuji Takata for the preparation of the single-crystal superalloys, and Mr. Takuma Kohata for the EPMA analysis. Publisher Copyright: © 2020

PY - 2021/3/15

Y1 - 2021/3/15

N2 - Oxidation resistance of Ni-base single crystal superalloy is substantially improved when melted using a CaO crucible compared to that melted using an Al2O3 crucible. In order to understand the underlying mechanism, sulfur segregation at the oxide/substrate interfaces was characterized using aberration corrected scanning transmission electron microscope with energy dispersive X-ray spectroscopy (STEM-EDS) and three-dimensional atom probe (3DAP). Although sulfur segregation at the interface was detected in both samples, the peak concentration of sulfur was found to be much lower in the sample melted in the CaO crucible, and CaS inclusions were found near the sub-grain boundaries. These experimental results suggest that the improvement in the cyclic oxidation resistance using the CaO crucible is attributed to the suppression of S segregation at the oxide/substrate interface by the trapping of S by dissolved Ca.

AB - Oxidation resistance of Ni-base single crystal superalloy is substantially improved when melted using a CaO crucible compared to that melted using an Al2O3 crucible. In order to understand the underlying mechanism, sulfur segregation at the oxide/substrate interfaces was characterized using aberration corrected scanning transmission electron microscope with energy dispersive X-ray spectroscopy (STEM-EDS) and three-dimensional atom probe (3DAP). Although sulfur segregation at the interface was detected in both samples, the peak concentration of sulfur was found to be much lower in the sample melted in the CaO crucible, and CaS inclusions were found near the sub-grain boundaries. These experimental results suggest that the improvement in the cyclic oxidation resistance using the CaO crucible is attributed to the suppression of S segregation at the oxide/substrate interface by the trapping of S by dissolved Ca.

KW - 3DAP

KW - Nickel

KW - Oxidation

KW - Sulfur segregation

KW - Superalloy

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Quantitative analysis of sulfur segregation at the oxide/substrate interface in Ni-base single crystal superalloy

Abstract

Keywords

ASJC Scopus subject areas

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