Interfaces in Oxides Formed on NiAlCr Doped with Y, Hf, Ti, and B

Journal Article · Mon Mar 20 04:00:00 UTC 2017 · Microscopy and Microanalysis

DOI: https://doi.org/10.1017/S1431927617000186 · OSTI ID:1394441

Boll, Torben ^[1]; Unocic, Kinga A. ^[2]; Pint, Bruce A. ^[2]; Stiller, Krystyna ^[1]

---

1. Chalmers Univ. of Technology, Goteborg (Sweden)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Abstract This study applies atom probe tomography (APT) to analyze the oxide scales formed on model NiAlCr alloys doped with Hf, Y, Ti, and B. Due to its ability to measure small amounts of alloying elements in the oxide matrix and its ability to quantify segregation,the technique offers a possibility for detailed studies of the dopant’s fate during high-temperature oxidation. Three model NiAlCr alloys with different additions of Hf, Y, Ti, and B were prepared and oxidized in O₂at 1,100°C for 100 h. All specimens showed an outer region consisting of different spinel oxides with relatively small grains and the protective Al₂O₃-oxide layer below. APT analyses focused mainly on this protective oxide layer. In all the investigated samples segregation of both Hf and Y to the oxide grain boundaries was observed and quantified. Neither B nor Ti were observed in the alumina grains or at the analyzed interfaces. The processes of formation of oxide scales and segregation of the alloying elements are discussed. The experimental challenges of the oxide analyses by APT are also addressed.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1394441
• Journal Information: Microscopy and Microanalysis, Journal Name: Microscopy and Microanalysis Journal Issue: 02 Vol. 23; ISSN 1431-9276; ISSN applab
• Publisher: Microscopy Society of America (MSA)Copyright Statement
• Country of Publication: United States
• Language: English