Influence of the oxidation behavior of Ti–6Al–4V alloy in dry air on the oxide layer microstructure

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.

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Effects of Gas Environments on Porous Silicon Photoluminescence

MRS Proceedings ◽

10.1557/proc-560-191 ◽

1999 ◽

Vol 560 ◽

Author(s):

G. Di Francia ◽

V. La Ferrara ◽

L. Lancellotti ◽

L. Quercia ◽

T. Fasolino

Keyword(s):

Porous Silicon ◽

Oxide Layer ◽

Electrochemical Etching ◽

Peak Wavelength ◽

Laser Illumination ◽

Dry Air ◽

Thin Oxide Layer ◽

Thin Oxide ◽

Photoluminescence Response

ABSTRACTThe photoluminescence response of a series of porous silicon samples, obtained by electrochemical etching of n-type CZ-silicon, has been recorded in various gas environments. A quenching is reported when porous silicon is in the presence of an oxidising ambient (dry air or acetone vapours in dry air). Process reversibility depends on the duration of laser illumination. Quenching is also recorded if porous silicon is in the presence of acetone vapours in nitrogen ambient, where complete reversibility is however shown. Moreover, the peak wavelength is red shifted in dry air and blue shifted in acetone vapours. Irreversible quenching is related to the growth of a thin oxide layer on the emitting nanostrucures.

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Oxidation behavior of bulk Ti3SiC2 at intermediate temperatures in dry air

Journal of Materials Research ◽

10.1557/jmr.2006.0046 ◽

2006 ◽

Vol 21 (2) ◽

pp. 402-408 ◽

Cited By ~ 31

Author(s):

H.B. Zhang ◽

Y.C. Zhou ◽

Y.W. Bao ◽

J.Y. Wang

Keyword(s):

Phase Transformation ◽

Low Temperatures ◽

Driving Force ◽

Oxidation Behavior ◽

Isothermal Oxidation ◽

Oxide Scales ◽

Temperature Oxidation ◽

Dry Air ◽

High Oxidation ◽

Anomalous Oxidation

The isothermal oxidation behavior of bulk Ti3SiC2 at intermediate temperatures from 500 to 900 °C in flowing dry air was investigated. An anomalous oxidation with higher kinetics at lower temperatures was observed. This phenomenon resulted from the formation of microcracks in the oxide scales at low temperatures. The generation of these microcracks was caused by a phase change in the oxide products, i.e., the transformation of anatase TiO2 to rutile TiO2. This phase transformation resulted in tensile stress, which provided the driving force for the formation of the microcracks during oxidation. Despite the existence of microcracks, the intermediate-temperature oxidation of Ti3SiC2 generally obeyed the parabolic rate law and did not exhibit catastrophic destruction due to the fact that cracks occurring in the oxide layers were partially filled with amorphous SiO2. Therefore, further high oxidation kinetics was prevented.

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Oxidation Behavior of Alumina-Forming Austenitic Steels in Superheated Steam at 700 °C

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4044530 ◽

2020 ◽

Vol 6 (3) ◽

Author(s):

Bingjie Xiao ◽

Nick Tepylo ◽

Xiao Huang ◽

Zhangjian Zhou ◽

Sami Penttilä

Keyword(s):

Weight Loss ◽

Weight Gain ◽

Oxide Layer ◽

Internal Oxidation ◽

Oxidation Behavior ◽

Superheated Steam ◽

External Surface ◽

Austenitic Steels ◽

Surface Oxide Layer ◽

Oxide Spallation

Abstract In this study, three alumina-forming austenitic (AFA) steels (Fe-18Ni-12Cr-AlNbC, Fe-18Ni-12Cr-Al, and Fe-18Ni-16Cr-AlNbC) were exposed to superheated steam (SHS) at 700 °C for 1000 h to study their oxidation behavior. The Fe-18Ni-16Cr-AlNbC alloy showed the best performance as it had the least weight gain due to a denser surface oxide layer and the lack of internal oxidation. The Fe-18Ni-12Cr-AlNbC alloy suffered from internal oxidation and had a greater weight gain than Fe-18Ni-16Cr-AlNbC, while Fe-18Ni-12Cr-Al experienced weight loss due to perhaps external oxide spallation, leaving a less protective Fe-oxide on the external surface.

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Study on Laser-Induced Oxidation of Ti6Al4V Alloy Under Two Different Reactive Atmospheres

Journal of Micro and Nano-Manufacturing ◽

10.1115/1.4046037 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Wei Zhao ◽

Guolong Zhao ◽

Ning He ◽

Liang Li ◽

Asif Iqbal

Keyword(s):

Laser Irradiation ◽

Oxide Layer ◽

Laser Fluence ◽

Oxidation Behavior ◽

Phase Identification ◽

Oxidation Reactions ◽

X Ray Diffraction ◽

Cross Sectional ◽

Subsurface Layers

Abstract The oxidation behavior of Ti6Al4V titanium alloy under laser irradiation in atmospheric and oxygen-assisted conditions was studied. A nanosecond-pulsed Yb: glass fiber laser was used. The thickness of oxide layer, microstructure, and phase composition of the material after laser irradiation were investigated. The characterization of the surface and subsurface microstructure, as well as the cross-sectional morphology were performed using scanning electron microscopy (SEM). The phase identification was performed using X-ray diffraction (XRD). The combined effects of accumulated laser fluence and reactive atmosphere on the oxidation behavior of Ti6Al4V were also studied in detail. With an increase in accumulated laser fluence, a porous and easily removable oxide layer gradually formed on the surface, whereas a compact oxide layer was also formed. At high accumulated laser fluence, the thickness of the porous oxide layer increased dramatically, while the change of thickness of compact oxide layer was not obvious. The reactive atmosphere also had a significant influence on the microstructure of the surface and subsurface layers. SEM and XRD results revealed existence of strong oxidation reactions that underwent in the condition of assisted oxygen delivery at a fixed accumulated laser fluence. The oxide layer was composed mainly of anatase and rutile titanium oxides.

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Oxidation Behavior of Fe–Al, Fe–Si and Fe–Al–Si Intermetallics

Materials ◽

10.3390/ma12111748 ◽

2019 ◽

Vol 12 (11) ◽

pp. 1748 ◽

Cited By ~ 9

Author(s):

Pavel Novák ◽

Kateřina Nová

Keyword(s):

Chemical Composition ◽

Aluminum Oxide ◽

Oxide Layer ◽

Power Plants ◽

Oxidation Behavior ◽

Ternary Alloys ◽

Synergic Effect ◽

Secondary Oxidation ◽

Oxidation Protection ◽

Phase And Chemical Composition

Iron aluminides are still deeply investigated materials for their use in power plants, automotive and chemical industry, and other sectors. This paper shows that it is possible to strongly improve their oxidation behavior by the addition of silicon. The description of the synergic effect of aluminum and silicon on the oxidation behavior of Fe–Al–Si alloys at 800 °C in air is presented. The oxidation rate, microstructure, phase, and chemical composition of these ternary alloys are compared with the binary Fe–Al and Fe–Si alloys. Results showed that the oxidation of Fe–Al–Si ternary alloys provides an oxide layer based on aluminum oxide with a low concentration of iron and silicon. Below this oxide layer, there is a layer of silicides formed as a result of depletion by aluminum, which forms a secondary oxidation protection.

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Improvement in the Oxidation Resistance of β-SiAlON Ceramics Produced from Mechanically Milled Powders

Journal of Nano Research ◽

10.4028/www.scientific.net/jnanor.18-19.281 ◽

2012 ◽

Vol 18-19 ◽

pp. 281-290

Author(s):

Onur Eser ◽

S. Kurama

Keyword(s):

Oxidation Resistance ◽

High Temperature Oxidation ◽

Oxidation Behavior ◽

Oxidation Process ◽

Isothermal Oxidation ◽

High Energy ◽

Particle Sizes ◽

Temperature Oxidation ◽

Dry Air ◽

Milled Powders

In the present study the oxidation behavior of β-SiAlON ceramics, which were produced from conventional and high energy mechanical milled powders, was investigated. High energy mechanically milled powders have lower particle sizes ( 130 nm) than those of conventional powders (216 nm) and fully densified at lower temperatures with less amount of additives. The amount of additive is an important parameter to improve the high temperature oxidation resistance of SiAlON ceramics. The cyclic and isothermal oxidation tests were carried out at 1300 and 1400°C in dry air environment. The weight gain of oxidized samples was measured during the oxidation process. The alteration of oxide layer was analyzed by XRD and SEM. The results indicate that oxidation resistance of the samples produced from mechanically milled powders with less amount of additive is higher than that of conventional one. Therefore, β-SiAlON ceramics which were sintered at 100°C lower temperatures with less amount of additive (3.5 wt. % Y2O3), showed a better oxidation resistance.

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