Oxidation Resistance Improvement of Ni-Base Single-Crystal Superalloy Melted in a CaO Crucible

Takuya Sugiyama, Satoshi Utada, Tadaharu Yokokawa, Makoto Osawa, Kyoko Kawagishi, Shinsuke Suzuki, Hiroshi Harada

Research output: Contribution to journalArticle

Abstract

An advanced Ni-base single-crystal superalloy, TMS-238, has the highest temperature capability, but there is still potential to improve its high-temperature properties. In the present study, aiming for that further improvement, TMS-238 was melted in a CaO crucible, which replaced an Al2O3 crucible. Creep tests at 1100 °C/137 MPa and cyclic oxidation tests at 1100 °C were conducted to compare the high-temperature properties of TMS-238 melted in an Al2O3vs a CaO crucible. Regardless of the melting crucible, the creep properties of the samples were equivalent. Meanwhile, TMS-238 melted in a CaO crucible exhibited better oxidation resistance. Although the composition of the oxide scale was almost the same, the sample melted in an Al2O3 crucible had its oxide scale spalled, while a continuous oxide scale was formed on the sample melted in a CaO crucible. Dissolved Ca capturing S as CaS and preventing segregation of S at the metal-oxide interface is a possible reason for the improvement of the oxide scale adhesiveness. The results indicated that melting in a CaO crucible can improve the oxidation resistance of the original superalloys while maintaining their creep properties.

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oxidation resistance
Crucibles
Oxidation resistance
heat resistant alloys
crucibles
Superalloys
Single crystals
Oxides
single crystals
creep properties
High temperature properties
Creep
oxides
Melting
melting
creep tests
metal oxides
Metals
Oxidation
oxidation

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys

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Oxidation Resistance Improvement of Ni-Base Single-Crystal Superalloy Melted in a CaO Crucible. / Sugiyama, Takuya; Utada, Satoshi; Yokokawa, Tadaharu; Osawa, Makoto; Kawagishi, Kyoko; Suzuki, Shinsuke; Harada, Hiroshi.

In: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, 01.01.2019.

Research output: Contribution to journalArticle

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