Fundamental studies on the transient stages of scale growth in Fe-22 wt.% Cr alloys

L. M. Fernandez Diaz, J. Zhu, G. R. Holcomb, P. D. Jablonski, D. E. Alman, S. Sridhar

Research output: Contribution to journalArticlepeer-review

Abstract

It is known that additions of reactive elements such as Ce, La or Y improve the properties of protective oxide-scales on Ni and Fe based alloys [1-3] by increasing oxide adhesion, decreasing the transient time until a continuous Cr2O3 layer is formed and decreasing the parabolic rate constant. Nevertheless, the precise roles played by these reactive elements to improve scales and the precise mechanisms by which they are incorporated into the scale during the surface treatment processes are unknown. Although they are believed to be associated with transport properties in the scale, it is not clear how this occurs or why it improves oxidation resistance. This project is aimed to gain understanding of the scale evolution in Fe-22 wt.% Cr alloys at 800 °C in dry air during the transient stage after 15 minutes of oxidation. The effect of La (120 and 290 ppm) and Ce (270 and 610 ppm) additions added during melt-stage processing are investigated. The surface oxidation process was imaged in-situ through a Confocal Scanning Laser Microscope (CSLM) and the results were correlated with post-experiment characterization through FEG-SEM and FIB-SEM combined with 3D reconstruction. The roles of rare-earth oxide particles on nucleation of Cr2O3 and blockage of short-circuit diffusion paths in the oxide scale and underlying metal are discussed.

Original languageEnglish (US)
Pages (from-to)425-431
Number of pages7
JournalDefect and Diffusion Forum
Volume283-286
DOIs
StatePublished - 2008
Externally publishedYes

Keywords

  • CrOscale growing
  • Fe based alloys
  • High temperature oxidation
  • Reactive elements

ASJC Scopus subject areas

  • Radiation
  • Materials Science(all)
  • Condensed Matter Physics

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