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Title: Isothermal Nature of Martensite Formation in Pt-Modified beta-NiAl Alloys

Abstract

No abstract prepared.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
909367
Report Number(s):
IS-J 7204
Journal ID: ISSN 1359-6454; ACMAFD; TRN: US200722%%1236
DOE Contract Number:
DE-AC02-07CH11358
Resource Type:
Journal Article
Resource Relation:
Journal Name: Acta Materialia
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; MARTENSITE; MATERIALS

Citation Formats

D.J. Sordelet, M.F. Besser, R.T. Ott, B.J. Zimmerman, W.D. Porter, and B. Gleeson. Isothermal Nature of Martensite Formation in Pt-Modified beta-NiAl Alloys. United States: N. p., 2007. Web. doi:10.1016/j.actamat.2006.11.038.
D.J. Sordelet, M.F. Besser, R.T. Ott, B.J. Zimmerman, W.D. Porter, & B. Gleeson. Isothermal Nature of Martensite Formation in Pt-Modified beta-NiAl Alloys. United States. doi:10.1016/j.actamat.2006.11.038.
D.J. Sordelet, M.F. Besser, R.T. Ott, B.J. Zimmerman, W.D. Porter, and B. Gleeson. Tue . "Isothermal Nature of Martensite Formation in Pt-Modified beta-NiAl Alloys". United States. doi:10.1016/j.actamat.2006.11.038.
@article{osti_909367,
title = {Isothermal Nature of Martensite Formation in Pt-Modified beta-NiAl Alloys},
author = {D.J. Sordelet and M.F. Besser and R.T. Ott and B.J. Zimmerman and W.D. Porter and B. Gleeson},
abstractNote = {No abstract prepared.},
doi = {10.1016/j.actamat.2006.11.038},
journal = {Acta Materialia},
number = ,
volume = ,
place = {United States},
year = {Tue Jan 30 00:00:00 EST 2007},
month = {Tue Jan 30 00:00:00 EST 2007}
}
  • Oxide growth stresses were measured in situ at 1100 C on commercial Pt-modified NiAl and NiCoCrAlY bond coat alloys using synchrotron X-rays. Measurements were taken on samples that had no preoxidation, as well as on samples that had experienced 24 one-hour thermal exposures at 1150 C, a condition known to induce rumpling in the Pt-modified NiAl alloy, but not in the NiCoCrAlY alloy. The NiCoCrAlY alloy showed continuous stress relaxation under all conditions, whereas the Pt-modified NiAl alloys would typically stabilize at a fixed (often non-zero) stress suggesting a higher creep strength in the 'Thermally Grown Oxide' on the lattermore » alloy, though the precise behavior was dependent on initial surface preparation. The formation of martensite in the Pt-modified NiAl alloys was also observed upon cooling and occurred at temperatures below 200 C for all of the samples observed. Based on existing models, this M{sub s} temperature is too low to account for the rumpling observed in these alloys.« less
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  • Molybdenum oxycarbide formed from oxidized Mo{sub 2}C or reduced MoO{sub 3} is an active and very selective catalyst for the isomerization of n-heptane compared to supported Pt. Deactivation experiments performed on the catalysts with different concentrations of organosulfur compounds show that molybdenum oxycarbide exhibits a very high resistance to deactivation, whereas with platinum-based catalysts deactivation occurs even at low sulfur concentration in the feed. Deactivation can be slowed by increasing the hydrogen partial pressure from 6 to 20 bar. In these conditions, the molybdenum oxycarbide shows no deactivation with sulfur concentrations up to 120 ppm of S. In addition, themore » deactivated molybdenum catalysts can be easily regenerated by mild oxidative treatment under flowing air at atmospheric pressure and 723 K for 2 h followed by a reactivation period under the hydrogen and hydrocarbon mixture.« less