Influence of additional elements on the oxidation behaviour of TiAl

Taniguchi, Shigeji; Shibata, Toshio

doi:10.1016/0966-9795(96)00017-9

Cited by 85 publications

(44 citation statements)

References 27 publications

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“…However, the mechanical properties of this alloy are greatly affected by the quantity and species of additive elements. [3,4] Besides, these alloys are sensitive with respect to oxidation.…”

Section: Introductionmentioning

confidence: 99%

Oxidation Behavior of TiAl-8Nb Turbine Blade Alloy

Teng

Nakatomi

Seetharaman

2007

Metall Mater Trans B

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The oxidation behavior of the TiAl-8Nb alloy has been investigated by the thermogravimetric method. Isothermal experiments were carried out in the temperature range of 1173 to 1473 K in air as atmosphere. The activation energy of the reaction was calculated from the results of the isothermal experiments. The results show that the reaction rate is controlled during the initial stages by the chemical reaction, while, at the later stages, the diffusion process is likely to be the rate-controlling step. Further, the rate-determining diffusion step is likely to be the self-diffusion of Ti in alloy. The microstructure and composition distribution of the oxide layer were analyzed by scanning electronic microscopy (SEM) and electron dispersion spectroscopy (EDS). A mechanism for oxidation of the TiAl-8Nb alloy in the experimental temperature range is proposed based on the experimental results.

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Section: Introductionmentioning

confidence: 99%

Oxidation Behavior of TiAl-8Nb Turbine Blade Alloy

Teng

Nakatomi

Seetharaman

2007

Metall Mater Trans B

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“…Previous results in [20] showed that the Nb content was much higher than V content in the outermost TiO 2 oxide scales in the specimen oxidized at 900°C. According to the valence-control rule [21], defect concentrations in TiO 2 lattice are reduced depending on the solution of Nb in TiO 2 to form a compact scale on the substrate and hence improve the oxidation resistance. Therefore, the doping effect of Nb was active to improve oxidation resistance of the alloy oxidized at 700°C.…”

Section: Discussionmentioning

confidence: 99%

The Isothermal Oxidation Behavior of a Ti3Al-Nb-V-Mo Alloy

Song¹

2010

TOCORRJ

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Abstract:The isothermal oxidation behavior of Ti-24Al-14Nb-3V-0.5Mo alloy in synthetic air from 700°C to 1000°C was studied. The main emphasis was focused on the effect of microstructure obtained by different processes of melting and hot rolling, i.e. large and duplex of 2 +B2, on the oxidation resistance. Regardless of the microstructure, the overall oxidation process of the specimens exposed at 700°C was dominantly controlled by the beneficial effect of Nb-addition due to the formation of a continuous -Al 2 O 3 layer in the scale. However, both specimens showed poor oxidation resistance above 900°C, especially for the as-rolled specimen, because of higher volume fraction of the 2 -phase. The spallation occurred in both specimens at 1000°C, which was probably relative to the formation of Ti 2 AlN between the thick scale and the substrate except for the TiO 2 and -Al 2 O 3 .

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“…Such growth mode makes oxide boundary bring compression stress, consequently results in Al 2 O 3 film distorted and forms many bulges till cracks are generated at the root, and at the moment TiO 2 grows in the cracks. As TiO 2 grows quickly, it gradually fills up the cracks among the bulges and covers the bulges to form vesicular texture which is composed of TiO 2 and Al 2 O 3 mixture [28,29] . This further certifies the reasons why discontinuous points occur in Figure 3 and pores exist in Figure 9.…”

Section: Oxidation Mechanismmentioning

confidence: 99%

High-temperature oxidation behavior of Al2O3/TiAl matrix composite in air

Fen

Feng

2008

Sci. China Ser. E-Technol. Sci.

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The oxidation behavior of Al 2 O 3 /TiAl in situ composites fabricated by hot-pressing technology was investigated at 900℃ in static air. The results indicate that the mass gains of the composites samples decrease gradually with increasing Nb 2 O 5 content and the inert Al 2 O 3 dispersoids effectively increase the oxidation resistance of the composites. The higher the Al 2 O 3 dispersoids content, the more pronounced the effect. The primary oxidation precesses obey approximately the linear laws, and the cyclic oxidation precesses follow the parabolic laws. The oxidized sample containing Ti 2 AlN and TiAl phases in the scales exhibits excellent oxidation resistance. The oxide scale formed after exposure at 900 for ℃ 120 h is multiple-layered, consisting mainly of an outer TiO 2 layer, an intermediate Al 2 O 3 layer, and an inner TiO 2 +Al 2 O 3 mixed layer. From the outer layer to the inner layer, TiO 2 +Al 2 O 3 mixed layer presents the transit of Al-rich oxide to Ti-rich oxide mixed layer. Near the substrate, cross-section micrograph shows a relatively loose layer, and micro-and macro-pores remain on this layer, which is a transition layer and transferres from Al 2 O 3 +TiO 2 scale to substrate. The thickness of oxide layer is about 20 μm. It is also found that continuous protective alumina scales can not be observed on the surface of oxidation scales. Ti ions diffuse outwardly to form the outer TiO 2 layer, while oxygen ions transport inwardly to form the inner TiO 2 +Al 2 O 3 mixed layer. Under long-time intensive oxidation exposure, the internal Al 2 O 3 scale has a good adhesiveness with the outer TiO 2 scale. No obvious spallation of the oxide scales occurs. The increased oxidation resistance by the presence of in situ Al 2 O 3 particulates is attributed to the enhanced alumina-forming tendency and thin and dense scale formation. Al 2 O 3 particulates enhance the potential barrier of Ti ions from M/MO interface to O/MO interface, thereby the TiO 2 growth rate decreases, which is also beneficial to improve the oxidation resistance. Moreover, the multi-structure of the TiO 2 +Al 2 O 3 mixed layer decreases the indiffusion of oxygen ions and also avails to improve the high temperature oxidation resistance of the as-sintered composites.Al 2 O 3 /TiAl matrix composite, oxidation resistance, high temperature

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Influence of additional elements on the oxidation behaviour of TiAl

Cited by 85 publications

References 27 publications

Oxidation Behavior of TiAl-8Nb Turbine Blade Alloy

Oxidation Behavior of TiAl-8Nb Turbine Blade Alloy

The Isothermal Oxidation Behavior of a Ti3Al-Nb-V-Mo Alloy

High-temperature oxidation behavior of Al2O3/TiAl matrix composite in air

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