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Effect of the /theta/-/alpha/-Al/sub 2/O/sub 3/ transformation on the oxidation behavior of /beta/-NiAl + Zr

Journal Article · · Oxid. Met.; (United States)
DOI:https://doi.org/10.1007/BF00846690· OSTI ID:5677290
Isothermal oxidation of NiAl + Zr has been performed over the temperature range of 800-1,200/degree/C and studied by TGA, XRD, and SEM. A discontinuous decrease in growth rate of two orders of magnitude was observed at 1,000/degree/C due to the formation of /alpha/-Al/sub 2/O/sub 3/ from /theta/-Al/sub 2/O/sub 3/. This transformation also resulted in a dramatic change in the surface morphology of the scales, as a whisker topography was changed into a weblike network of oxide ridges and radial transformation cracks. It is believed that the ridges are evidence for a short-circuit outward aluminum diffusion growth mechanism that has been documented in a number of /sup 18/O tracer studies.
Research Organization:
NASA Lewis Research Center, Cleveland, OH (USA)
OSTI ID:
5677290
Journal Information:
Oxid. Met.; (United States), Journal Name: Oxid. Met.; (United States) Vol. 31:3-4; ISSN OXMEA
Country of Publication:
United States
Language:
English