ISSN:
1573-4889
Keywords:
18O tracer dffusion
;
Al2O3 scales
;
NiCrAl alloys
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Diffusion processes in Al 2 O 3 scales formed on NiCrAl + Zr alloys were studied by the proton activation technique employing the 18 O isotope as a tracer. The 18 O profiles identified a zone of oxide penetration beneath the external scale. Both this subscale formation and the outer Al 2 O 3 scale thickness were shown by this technique to increase with Zr content in the alloy. Estimated k p 's from scale thicknesses were in agreement with gravimetric measurements for various Zr levels. Alternate exposures in O and 18 O revealed that oxygen inward transport was the primary growth mechanism. A qualitative analysis of these 18 O profiles indicated that the oxygen transport was primarily via short-circuit paths, such as grain boundaries.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00742122
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