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

Research output: Contribution to journalArticlepeer-review

2 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 languageEnglish
Article number113616
JournalScripta Materialia
Volume194
DOIs
Publication statusPublished - 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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