Effect of environment on the scale formed on oxide dispersion strengthened FeCrAl at 1050°C and 1100°C

K. A. Unocic; E. Essuman; S. Dryepondt; B. A. Pint

doi:10.3184/096034012X13317275660176

Effect of environment on the scale formed on oxide dispersion strengthened FeCrAl at 1050°C and 1100°C

K. A. Unocic, E. Essuman, S. Dryepondt, B. A. Pint

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Abstract

The surface scale formed on specimens of a commercial oxide dispersion strengthened (ODS) FeCrAl alloy (PM2000™) exposed for 1 and 500 h at 1050°C in dry O₂, Air10%H₂O and Ar10%H₂O consisted of a two-layer a-Al₂O₃ structure with a columnar grain inner layer and a finer grain outer layer. The alumina scales formed in Air10%H₂O and Ar10%H₂O were slightly more than half of the thickness of the scale formed in dry O₂. The same two-layer structure was also observed after exposure for 500 h at 1100°C in dry O ₂ and 50%CO₂+50%H₂O. The alumina scales formed in both atmospheres were similar in thickness. Oxides rich in Y and Ti at the gas - scale interface grew in size and number with time in each case. Using analytical transmission electron microscopy, alumina grain boundary segregation of both Y and Ti was evident near the gas interface but only Y segregation was detected near the metal interface. This difference was attributed to Ti depletion in the adjacent metal and the rapid outward flux of the smaller Ti ion through the scale.

Original language	English
Pages (from-to)	171-180
Number of pages	10
Journal	Materials at High Temperatures
Volume	29
Issue number	3
DOIs	https://doi.org/10.3184/096034012X13317275660176
State	Published - Aug 2012

Keywords

Alumina
CO-HO
Dry air
Fecral
Oxidation
Oxide dispersion strengthened alloys
Water vapour

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title = "Effect of environment on the scale formed on oxide dispersion strengthened FeCrAl at 1050°C and 1100°C",

abstract = "The surface scale formed on specimens of a commercial oxide dispersion strengthened (ODS) FeCrAl alloy (PM2000{\texttrademark}) exposed for 1 and 500 h at 1050°C in dry O2, Air10%H2O and Ar10%H2O consisted of a two-layer a-Al2O3 structure with a columnar grain inner layer and a finer grain outer layer. The alumina scales formed in Air10%H2O and Ar10%H2O were slightly more than half of the thickness of the scale formed in dry O2. The same two-layer structure was also observed after exposure for 500 h at 1100°C in dry O 2 and 50%CO2+50%H2O. The alumina scales formed in both atmospheres were similar in thickness. Oxides rich in Y and Ti at the gas - scale interface grew in size and number with time in each case. Using analytical transmission electron microscopy, alumina grain boundary segregation of both Y and Ti was evident near the gas interface but only Y segregation was detected near the metal interface. This difference was attributed to Ti depletion in the adjacent metal and the rapid outward flux of the smaller Ti ion through the scale.",

keywords = "Alumina, CO-HO, Dry air, Fecral, Oxidation, Oxide dispersion strengthened alloys, Water vapour",

author = "Unocic, {K. A.} and E. Essuman and S. Dryepondt and Pint, {B. A.}",

year = "2012",

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language = "English",

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AU - Unocic, K. A.

AU - Essuman, E.

AU - Dryepondt, S.

AU - Pint, B. A.

PY - 2012/8

Y1 - 2012/8

N2 - The surface scale formed on specimens of a commercial oxide dispersion strengthened (ODS) FeCrAl alloy (PM2000™) exposed for 1 and 500 h at 1050°C in dry O2, Air10%H2O and Ar10%H2O consisted of a two-layer a-Al2O3 structure with a columnar grain inner layer and a finer grain outer layer. The alumina scales formed in Air10%H2O and Ar10%H2O were slightly more than half of the thickness of the scale formed in dry O2. The same two-layer structure was also observed after exposure for 500 h at 1100°C in dry O 2 and 50%CO2+50%H2O. The alumina scales formed in both atmospheres were similar in thickness. Oxides rich in Y and Ti at the gas - scale interface grew in size and number with time in each case. Using analytical transmission electron microscopy, alumina grain boundary segregation of both Y and Ti was evident near the gas interface but only Y segregation was detected near the metal interface. This difference was attributed to Ti depletion in the adjacent metal and the rapid outward flux of the smaller Ti ion through the scale.

AB - The surface scale formed on specimens of a commercial oxide dispersion strengthened (ODS) FeCrAl alloy (PM2000™) exposed for 1 and 500 h at 1050°C in dry O2, Air10%H2O and Ar10%H2O consisted of a two-layer a-Al2O3 structure with a columnar grain inner layer and a finer grain outer layer. The alumina scales formed in Air10%H2O and Ar10%H2O were slightly more than half of the thickness of the scale formed in dry O2. The same two-layer structure was also observed after exposure for 500 h at 1100°C in dry O 2 and 50%CO2+50%H2O. The alumina scales formed in both atmospheres were similar in thickness. Oxides rich in Y and Ti at the gas - scale interface grew in size and number with time in each case. Using analytical transmission electron microscopy, alumina grain boundary segregation of both Y and Ti was evident near the gas interface but only Y segregation was detected near the metal interface. This difference was attributed to Ti depletion in the adjacent metal and the rapid outward flux of the smaller Ti ion through the scale.

KW - Alumina

KW - CO-HO

KW - Dry air

KW - Fecral

KW - Oxidation

KW - Oxide dispersion strengthened alloys

KW - Water vapour

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JO - Materials at High Temperatures

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Effect of environment on the scale formed on oxide dispersion strengthened FeCrAl at 1050°C and 1100°C

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