TY - JOUR
T1 - An electron microscopy investigation of the transient stage oxidation products in an Fe-22Cr alloy with ce and la additions exposed to dry air at 1073 K (800 °c)
AU - Zhu, Jingxi
AU - Fernández Díaz, Laura M.
AU - Holcomb, Gordon R.
AU - Jablonski, Paul D.
AU - Cowen, Christopher J.
AU - Alman, David E.
AU - Laughlin, David E.
AU - Sridhar, Seetharaman
PY - 2011/1
Y1 - 2011/1
N2 - In this study, the effects of Ce (270 ppm) and La (120 ppm) mischmetal additions on the transient oxidation of an Fe-22Cr alloy were investigated. The oxidation process was imaged in situ using a confocal scanning laser microscope. The oxidation microstructures were studied by scanning electron microscopy, energy dispersive X-ray analysis, and transmission electron microscopy with the help of focused ion beam in situ lift-out specimen preparation. The Ce and La, referred to as reactive elements, were found in nonmetallic inclusion particles in the forms of oxides, sulfides, and phosphates. An affected zone formed around rare earth (RE)-containing inclusion particles at the alloy free surface during the transient oxidation. This zone consisted of an internal Cr-oxide formed beneath the particle as well as a thinner external oxide scale on the surface compared with the surroundings. The relation of this microstructure to oxidation kinetics is discussed. With time, the RE elements diffused into the scale from the RE particles on the alloy surface during the high-temperature exposure. A diffusion mechanism is presented to describe these observations.
AB - In this study, the effects of Ce (270 ppm) and La (120 ppm) mischmetal additions on the transient oxidation of an Fe-22Cr alloy were investigated. The oxidation process was imaged in situ using a confocal scanning laser microscope. The oxidation microstructures were studied by scanning electron microscopy, energy dispersive X-ray analysis, and transmission electron microscopy with the help of focused ion beam in situ lift-out specimen preparation. The Ce and La, referred to as reactive elements, were found in nonmetallic inclusion particles in the forms of oxides, sulfides, and phosphates. An affected zone formed around rare earth (RE)-containing inclusion particles at the alloy free surface during the transient oxidation. This zone consisted of an internal Cr-oxide formed beneath the particle as well as a thinner external oxide scale on the surface compared with the surroundings. The relation of this microstructure to oxidation kinetics is discussed. With time, the RE elements diffused into the scale from the RE particles on the alloy surface during the high-temperature exposure. A diffusion mechanism is presented to describe these observations.
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U2 - 10.1007/s11661-010-0493-y
DO - 10.1007/s11661-010-0493-y
M3 - Article
AN - SCOPUS:78650731602
SN - 1073-5623
VL - 42
SP - 121
EP - 137
JO - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
JF - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
IS - 1
ER -