Grain boundary segregation of cation dopants in {alpha}-Al{sub 2}O{sub 3} scales

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:459331

Pint, B A; Alexander, K B

A Fe-20at.%Cr-10%Al matrix was dispersed with a wide range of different oxides in order to study the effect of oxygen-active dopants on the high-temperature growth and adhesion of {alpha}-Al{sub 2}O{sub 3} scales. Effect of these various cation dopants on the alumina scale microstructure was correlated with dopant ion segregation to the {alpha}-Al{sub 2}O{sub 3} grain boundaries using analytical electron microscopy. Elements such as Mn and V showed little effect on the oxide scale and were not observed to segregate. Elements such as Y and Gd resulted in finer, more columnar {alpha}-Al{sub 2}O{sub 3} grains and were segregated to scale grain boundaries. However, Ti, Ta, Ca, and Nb also were found to segregate but had a lesser effect on scale morphology. This indicates that cation segregation to scale grain boundaries is not a sufficient condition to achieve beneficial oxidation effects. The driving force for segregation in growing alumina scales is discussed.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States); Oak Ridge Inst. for Science and Education, TN (United States)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 459331
• Report Number(s): CONF-961040--20; ON: DE97002971
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
ALUMINIUM OXIDES
CHROMIUM ALLOYS
DISPERSION HARDENING
DOPED MATERIALS
IRON BASE ALLOYS
OXIDATION
SCALING
SEGREGATION