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

SCRIPTA MATERIALIA

卷:194

Article

Tabata, Chihiro^1,2  Kawagishi, Kyoko^1,3  Uzuhashi, Jun¹  Ohkubo, Tadakatsu¹  Hono, Kazuhiro¹  Yokokawa, Tadaharu¹  Harada, Hiroshi¹  Suzuki, Shinsuke^2,3,4 

[1] Natl Inst Mat Sci NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 3050047, Japan

[2] Waseda Univ, Dept Appl Mech & Aerosp Engn, Shinjuku Ku, 3-4-1 Okubo, Tokyo 1698555, Japan

[3] Waseda Univ, Dept Mat Sci, Shinjuku Ku, 3-4-1 Okubo, Tokyo 1698555, Japan

[4] Waseda Univ, Kagami Mem Inst Mat Sci & Technol, Shinjuku Ku, 2-8-26 Nishiwaseda, Tokyo 1690051, Japan

关键词: Nickel;    Superalloy;    Oxidation;    3DAP;    Sulfur segregation;   

DOI  :  10.1016/j.scriptamat.2020.11.003

来源: Elsevier

【 摘 要 】

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. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

【 授权许可】

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