Interfaces in Oxides Formed on NiAlCr Doped with Y, Hf, Ti, and B. (20th March 2017)

• Record Type: Journal Article
• Authors: Boll, Torben; Unocic, Kinga A.; Pint, Bruce A.; Stiller, Krystyna
• Editors: Thuvander, Mattias; Cairney, Julie; Gerstl, Stephan
• Is Part Of: Microscopy and microanalysis. Volume 23:Number 2(2017)
• Page Start: 396
• Page End: 403
• Publication Date: 2017-03-20
• Subjects: oxidation, -- diffusion, -- grain boundaries, -- reactive elements, -- atom probe tomography; Microscopy -- Periodicals; Microchemistry -- Periodicals; 502.82
• DOI: 10.1017/S1431927617000186
• Languages: English
• ISSNs: 1431-9276

Abstract

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, t he 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 O2 at 1, 100°C for 100 h. All specimens showed an outer region consisting of different spinel oxides with relatively small grains and the protective Al2 O3 -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.