High-temperature oxidation of Al–Cu–Fe–Be quasicrystalline powders

2003 ◽  
Vol 18 (8) ◽  
pp. 1837-1841 ◽  
Author(s):  
E. Fleury ◽  
J. S. Kim ◽  
D. H. Kim ◽  
W. T. Kim
Keyword(s):  
High Temperature ◽  
Oxide Layer ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Icosahedral Phase ◽  
Air Oxidation ◽  
Temperature Oxidation ◽  
Β Phase ◽  
Efficient Protection ◽  
The Stability

The oxidation behavior in air of gas atomized Al–Cu–Fe–Be powders was investigated during isothermal exposures at 750, 800, and 830 °C. Oxidation data obtained at 750 °C for Al–Cu–Fe and Al–Cu–Fe–Cr powders are also presented and used as references. Thermogravimetric analyses showed that Be significantly improved the oxidation resistance of the icosahedral phase at 750 °C. At this temperature the i-phase in Al–Cu–Fe–Be powders was found to be stable even after oxidation for 300 h, while oxidation at and beyond 800 °C led to the formation of a cubic β′-phase. Auger analyses suggested that, in addition to its role on the stability of the icosahedral phase, the presence of Be in the oxide layer provided efficient protection against air oxidation at high temperature.

Influence Mechanism of Cu on High Temperature Oxidation Behavior of Titanium Alloys

2019 ◽  
Vol 944 ◽  
pp. 110-119 ◽  
Author(s):  
Hang Chen ◽  
Guang Bao Mi ◽  
Pei Jie Li ◽  
Chun Xiao Cao
Keyword(s):  
High Temperature ◽  
Grain Boundaries ◽  
Oxide Layer ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Temperature Oxidation ◽  
Oxidation Rates ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Oxidation Surface

The oxidation behavior and mechanism of Ti-Cu alloys (0≤w(Cu)≤20%) in the temperature range of 1000°C～1300°C are studied by thermogravimetric analysis(TGA) combined with SEM, EDS and XRD analysis methods. The results show that the oxidation rates of Ti-Cu alloys increase sharply when the temperature rises above 1000°C. The oxidation products have a three-layer structure, from the outside to the inside, which are dense outer oxide layer of TiO2, porous inner oxide layer of low valence oxide of Ti and Cu-enriched layer. With the increase of the temperature, the thicknesses of oxide layers of Ti-Cu alloy increase and the Cu-enriched phase increases gradually and melts. The melting Cu-enriched phase flows to the oxidation surface along the grain boundaries of the oxide layer. The high temperature oxidation resistance of Ti-Cu alloys declines with the increase of Cu content. The main reason is that more liquid Cu-enriched phase is formed and flows to the oxidation surface along the oxide grain boundaries in the Ti-Cu alloy, and Ti and O ions can diffuse more easily along the liquid Cu-enriched phase, which increases the oxidation rates.

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.

Characterization and Oxidation Damage Modelling of MCrAlY

2006 ◽  
Author(s):  
Emanuele Pietrangeli ◽  
Filippo Cappuccini ◽  
Michelangelo Bellacci ◽  
Federico Iozzelli ◽  
Marco Romanelli
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Oxide Layer ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Surface Oxide ◽  
Life Assessment ◽  
Surface Oxide Layer ◽  
Temperature Oxidation ◽  
Β Phase

Overlay coatings based on the MCrAlY alloy system (M is Ni, CO or both) are among the most important protective coating materials applied in the hottest section of gas turbine to counteract hot corrosion and high temperature oxidation. MCrAlY coatings are arranged in γ/β-phase system, where β-phase is the Al reserve for the surface oxide layer formation. Like any coating designed to resist oxidative environments at high temperatures, MCrAlYs should be capable of developing a thermodynamically stable, slow-growing and adherent surface oxide layer. In the current paper, two HVOF thermal sprayed MCrAlYs deposited on a Ni-based superalloy have been investigated in order to assess the different high temperature oxidation resistance. Isothermal oxidation tests were performed on NiCoCrAlY coating (GT33®) and CoNiCrAlY coating (Amdry995®) at four temperatures for thousand hours. Coating damage was evaluated by measures of outer and inner β-phase depletion, interdiffusion zone thickness and Al reduction. Both coatings have shown optimal microstructural stability but NiCoCrAlY coating, in virtue of greater Ni and Al content, proved superior high temperature oxidation resistance. A useful model for life assessment of gas turbine buckets coatings was extrapolated from microstructure evolution data.

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