Oxidation Of AI-Cu-Fe Quasicrystals

1998 ◽  
Vol 553 ◽  
Author(s):  
B. I. Wehner ◽  
U. Köster
Keyword(s):  
Oxide Layer ◽  
Oxidation Behavior ◽  
Copper Ions ◽  
High Growth ◽  
High Growth Rate ◽  
Protective Oxide ◽  
Temperature Oxidation ◽  
Concentration Changes ◽  
High Temperature Oxidation Behavior ◽  
In The Beginning

AbstractThe oxidation behavior of i-A163Cu25Fe12 at 800°C in air was investigated by means of TGA, XRD, SEM and TEM. In the beginning a homogeneous oxide layer is formed by the subsequent growth of metastable γ-Al2O3 and Θ-Al2O3. Nucleation of the thermodynamical stable α-Al2O3 occurs at the interface oxide/quasicrystal. The following growth of α-Al2O3 through the oxide layer leads to the formation of oxide nodules. The high growth rate of the α-Al2O3 can be explained by the incorporation of copper ions. The oxidation resistance of the quasicrystal is insufficient at high temperatures, because no protective oxide layer is formed. The high temperature oxidation behavior of Al-Cu-Fe quasicrystal and the aluminides β-FeAl and β-NiAl is compared regarding the oxidation rate, the oxide phases and the concentration changes in the material due to selective oxidation of aluminum.

High-temperature oxidation behavior of arc ion plated NiCoCrAlYSiB coatings on cobalt-based superalloy

2006 ◽  
Vol 21 (3) ◽  
pp. 737-746 ◽  
Author(s):  
Y.J. Tang ◽  
Q.M. Wang ◽  
F.H. Yuan ◽  
J. Gong ◽  
C. Sun
Keyword(s):  
Cross Sections ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Alloy Element ◽  
Oxide Scales ◽  
Protective Oxide ◽  
Temperature Oxidation ◽  
Ion Plating ◽  
Aluminide Coatings ◽  
High Temperature Oxidation Behavior

NiCoCrAlYSiB coatings were deposited on the Co-based superalloy K40 by arc ion plating (AIP). The oxidation behavior of the bare alloy and of the coated specimens was tested in static air for 200 h at 1000 °C and 100 h at 1050 °C. The results showed that the oxidation rate of the system was greatly reduced by the addition of the NiCoCrAlYSiB coatings. Thin and adherent α–Al2O3 scales that formed on the coated specimens protected the substrates from further oxidation attack while non-protective oxide scales, mainly of Cr2O3 and CoCr2O4, appeared on bare K40 alloy. Element profiles on metallographic cross sections indicated that apparent interdiffusion occurred between the coatings and the substrates. The interdiffusion behavior and the resulting microstructure were investigated. As compared to aluminide coatings, NiCoCrAlYSiB coatings have less influence on the substrate microstructure.

Effect of Mo on the High Temperature Oxidation Behavior of Co-Al-W Based Alloys

2013 ◽  
Vol 747-748 ◽  
pp. 754-759 ◽  
Author(s):  
Fei Fan ◽  
Hao Sun ◽  
Di Zhao ◽  
Jiang Bo Sha
Keyword(s):  
High Temperature ◽  
Oxide Film ◽  
Oxide Layer ◽  
Outer Layer ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Oxidation Kinetic ◽  
Complex Oxide ◽  
Temperature Oxidation ◽  
High Temperature Oxidation Behavior

2 at.% and 4 at.% Mo were added to Co-9Al-9W-2Ta-0.02B alloy to replace W (hereafter referred to as the alloys of 2Mo and 4Mo, respectively; Mo-free alloy was referred to as the 0Mo alloy). The effects of Mo additions on the high temperature oxidation behavior of the alloys at 800 °C in air have been studied. The results indicated that, after oxidation in air at 800 °C for 100 h, the oxide film of the 0Mo alloy remained intact, but the cracking and spallation of the oxide film took place in the alloys of 2Mo and 4Mo. Oxidation kinetic curves revealed weight gain per unit area of the 0Mo alloy was 36.86 mg·cm-2, which was lower than that of the alloys of 2Mo (65.16 mg·cm-2) and 4Mo (48.54mg·cm-2). These suggested that the 0Mo alloy displayed superior oxidation resistance compared to the alloys of 2Mo and 4Mo caused by the formation of volatile MoO3 oxide, and sharp compressive stress formed in the outer layer during the oxidation. The oxide layer was composed of three layers of the Co3O4 + CoO outer layer, middle complex oxide layer containing Co, Al and W (Mo), inner Al2O3 layer and γ/Co3W zone adhere to the γ/γ' substrate.

scholarly journals High Temperature Oxidation Behavior of an Equimolar Cr-Mn-Fe-Co High-Entropy Alloy

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4259
Author(s):  
Lin Wang ◽  
Quanqing Zeng ◽  
Zhibao Xie ◽  
Yun Zhang ◽  
Haitao Gao
Keyword(s):  
High Temperature ◽  
Oxide Layer ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
High Entropy Alloy ◽  
Spinel Type ◽  
Temperature Oxidation ◽  
Outward Diffusion ◽  
High Entropy ◽  
High Temperature Oxidation Behavior

The oxidation behavior of an equimolar Cr-Mn-Fe-Co high-entropy alloy (HEA) processed by 3D laser printing was investigated at 700 °C and 900 °C. The oxidation kinetics of the alloy followed the parabolic rate law, and the oxidation rate constant increased with the rising of the temperature. Inward diffusion of oxygen and outward diffusion of cations took place during the high-temperature oxidation process. A spinel-type oxide was formed on the surface, and the thickness of the oxide layer increased with the rising of experimental temperature or time. The exfoliation of the oxide layer took place when the test was operated at 900 °C over 12 h. During oxidation tests, the matrix was propped open by oxides and was segmented into small pieces. The formation of loose structures had great effects on the high-temperature oxidation resistance of the HEA.

High Temperature Oxidation Behavior of Si-Mo Ferritic Ductile Cast Iron

2010 ◽  
Vol 654-656 ◽  
pp. 542-545 ◽  
Author(s):  
Kyeong Hwan Choe ◽  
Sang Mok Lee ◽  
Kyong Whoan Lee
Keyword(s):  
Cast Iron ◽  
High Temperature ◽  
Oxide Layer ◽  
Test Temperature ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Ductile Cast Iron ◽  
Ferrous Alloy ◽  
Temperature Oxidation ◽  
High Temperature Oxidation Behavior

High temperature oxidation behavior of Si-Mo ferritic ductile cast iron was investigated in the point of the effect of chromium and vanadium addition. The addition of Cr promoted the formation of as-cast pearlite around carbide which exists in cell boundary, which was eliminated during annealing process. The addition of vanadium promoted the precipitation of tiny carbide and reduced the grain size of ferrite. As the test temperature increased, the change of volume increased, on the other hand, the change of weight decreased above 1173K. In the case of Cr added specimen, the change of weight decreased with the increase of test temperature because of the presence of Cr oxide layer. The vanadium added specimens showed higher increase in the weight and volume change. The oxide layer of vanadium added specimen had very porous structure and showed severe internal oxidation. It is due to the catastrophic oxidation characteristic of vanadium alloyed ferrous alloy.

scholarly journals High-Temperature Oxidation Behavior and Kinetics of Forged 12Cr-MoVW Steel

2017 ◽  
Vol 62 (2) ◽  
pp. 1099-1104
Author(s):  
Yong Hwan Kim ◽  
Jeong-Jung Oak ◽  
Ki-Chang Bae ◽  
Wook Jin Lee ◽  
Yong Ho Park
Keyword(s):  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
X Ray Diffraction ◽  
Protective Oxide ◽  
Cross Sectional ◽  
Temperature Oxidation ◽  
Protective Oxide Layer ◽  
X Ray ◽  
High Temperature Oxidation Behavior ◽  
Kinetics Of

AbstractThe oxidation kinetics of forged 12Cr-MoVW steel was investigated in an air (N2+O2) atmosphere at 873-1073 K (Δ50 K) using thermogravimetric analysis. The oxidized samples were characterized using X-ray diffraction, and the surface and cross-sectional morphologies were examined using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The forged 12Cr-MoVW steel samples exhibited parabolic behavior and a low oxidation rate compared with their as-cast counterparts. A protective oxide layer was uniformly formed at relatively low temperature (≤973 K) for the forged samples, which thus exhibited better oxidation resistance than the as-cast ones. These oxides are considered solid-solution compounds such as (Fe, Cr)2O3.

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