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On the use of markers and tracers to establish the growth mechanism of alumina scales during high temperature oxidation
Author(s) -
Young E. W. A.,
Bishop H. E.,
De Wit J. H. W.
Publication year - 1986
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740090306
Subject(s) - nial , oxide , alloy , noble metal , diffusion , metal , chemistry , metallurgy , intermetallic , materials science , chemical engineering , thermodynamics , physics , engineering
Various ‘marker methods’ have been applied to study the oxidation mechanism of NiAl and Ni‐15Cr‐24Al‐.3Y from 1170 K to 1370 K. Experiments were performed using noble metal markers. The behaviour of both vacuum deposited noble metals as well as implanted noble metals was studied. Also 18 O tracers were used. RBS, 18 O(p, α) 15 N resonance spectrometry and SIMS analysis were performed to investigate the alumina scale composition and the position of the marker after oxidation of alloys. The results show that (at 1170 K) NiAl oxidizes mainly by outward diffusion of Al through the oxide scale. It is also shown that noble metal markers may give misleading results. The oxidation mechanism of Ni‐15Cr‐24Al‐.3Y is much more complex. The oxide scale formed on this alloy contains Ni, Cr and Y‐rich oxide regions. These regions contribute to the apparent overall oxidation mechanism of the alloy.