Sputtered intermetallic Ti–Al–X coatings: phase formation and oxidation behavior

Leyens, Christoph; Schmidt, Michael; Peters, M.; Kaysser, W. A.

doi:10.1016/s0921-5093(97)00652-7

Cited by 60 publications

(18 citation statements)

References 11 publications

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“…[7,8] Also, conventional aluminide coatings, manufactured by pack or chemical vapor deposition aluminizing, exhibit poor longterm properties, mainly due to the formation of very brittle phases (TiAl 3 and TiAl 2 ) in the coating layer. [9] Therefore, a number of recent studies [10][11][12][13] have been aimed at the development of alumina-forming TiAl-based alloys, which are expected to be more suitable as coating materials due to their similarity to high-strength ␥-TiAl alloys with respect to their physical and chemical properties.…”

Section: Introductionmentioning

confidence: 99%

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Fundamental considerations for the development of oxidation-resistant alloys and coatings based on γ-TiAl

Singheiser

Niewolak

Shemet

et al. 2003

Metall Mater Trans A

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Alloys based on ␥-TiAl are promising high-temperature materials that may replace conventional heatresistant steels and superalloys in applications where high strength in combination with low density is required. However, an important hindrance to the use of ␥-TiAl alloys at high temperatures is their relatively poor oxidation resistance and sensitivity against environmentally induced embrittlement. This material degradation is related to the poor protective properties of the mixed TiO 2 /Al 2 O 3 surface scales which form on the surface during high-temperature exposure. Recently, it was shown that protective alumina scale formation on ␥-TiAl can be obtained by small additions of Ag. This effect was found to be related to the formation of Z phase in the subscale depletion layer at the expense of ␣ 2 -Ti 3 Al. It was found that the beneficial effect of Ag can be suppressed if the alloys contain additional ␣ 2 -stabilizing elements, such as Nb, as is the case for most (semi)commercial, high-strength alloys. Therefore, recent efforts have concentrated on developing Ag-containing ␥-TiAl alloys as oxidation-resistant coatings for high-strength titanium aluminides. Preliminary results using magnetron sputtering have shown that, due to the similarities in chemical and physical properties of the coating and base material, the Ag-containing material offers promising potential to be qualified as a coating material for reducing the oxidation-induced degradation of titanium aluminides.

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Section: Introductionmentioning

confidence: 99%

“…Both types of materials have, therefore, been proposed as coating materials for high-strength ␥-TiAl and Ti-based alloys. [10][11][12][13][14][15] However, a major disadvantage of the Ti-Al-Cr coatings is the required high Cr content of around 10 at. pct to obtain protective alumina formation.…”

Section: Introductionmentioning

confidence: 99%

Fundamental considerations for the development of oxidation-resistant alloys and coatings based on γ-TiAl

Singheiser

Niewolak

Shemet

et al. 2003

Metall Mater Trans A

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“…When no external heating is used during the coating deposition, substrate temperatures are comparatively low due to impinging species and argon ions as well as latent heat of condensation. Therefore, the microstructure change of the substrate alloy can be avoided during deposition, which is sometimes a problem for plasma spraying and evaporation techniques on heat sensitive materials [17]. Some researchers studied the oxidation of TiAl alloy and its coating [4−5, 8, 12], but few investigated the influence of the surface treatment on the oxidation behavior.…”

Section: Introductionmentioning

confidence: 99%

Influence of surface finish and annealing treatment on oxidation behavior of Ti-48Al-8Cr-2Ag alloy

Liu

2009

J. Cent. South Univ. Technol.

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The effect of surface finish and annealing treatment on the oxidation behavior of Ti-48Al-8Cr-2Ag (molar fraction, %) alloy was investigated at 900 and 1 000 ℃, respectively in air. Thermal gravimetric analysis (TGA) was conducted for the characterization of oxidation kinetics. The microstructures of oxide scales were studied by scanning electron microscopy (SEM) and transmission election microscopy (TEM) techniques. Unfavorable effect of the annealing treatment on the oxidation behavior of the coating was also investigated. The results indicate that the oxidation behavior of the alloy is influenced by surface finish and annealing treatment. The oxidation rate of ground sample is lower than that of the polished alloy at 1 000 ℃ in air. The former forms a scale of merely Al 2 O 3 , and the latter forms a scale of the mixture of Al 2 O 3 and TiO 2 . Annealing can improve the formation of TiO 2 .

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“…However, due to their low room temperature ductility these materials are difficult to manufacture: shape forming and joining. Thus, it is reasonable to develop strategies for the deposition of thin films based on titanium aluminides [3]. During the last decade, the authors have used TieAl system thin films as predictive alloys, first for developing new doping strategies and secondly to evaluate their physical and chemical properties for new applications [4,5].…”

Section: Introductionmentioning

confidence: 99%

Nanometric multilayers: A new approach for joining TiAl

et al. 2006

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A novel intermetallic alloy diffusion bonding procedure is being developed. The innovative aspect relies on the use of sputtered nanometallic multilayers made up of the elements present in the bulk intermetallics to enhance the bonding mechanisms. For this purpose a deep knowledge of the multilayer thin films is required, focusing on thermal phase stability and grain size evolution. g-TiAl was selected for this study and Ti/Al multilayer thin films with nanometric period (L ¼ 4 nm) were deposited onto Tie(45e49)Ale(3e2)Nbe2Cr (at.%) substrates by d.c. magnetron sputtering. The as-deposited titanium and aluminium nanolayers with crystallite sizes of 5e50 nm evolve toward the equilibrium g-TiAl structure after heat treatment for at least up to 600 C at a 10 C min ÿ1 heating rate. Whatever the heating temperature and holding time, between 600 and 1000 C, the g-TiAl phase is stable. During the thermal cycle the growth of the nanometric grains is promoted, this effect being more pronounced as the temperature and holding time increase. Consequently, the hardness decreases from 11.9 GPa (600 C, 1 h) to 6.5 GPa (1000 C, 3 h). This study allowed the thermal treatment required to join g-TiAl parts to be established.

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Sputtered intermetallic Ti–Al–X coatings: phase formation and oxidation behavior

Cited by 60 publications

References 11 publications

Fundamental considerations for the development of oxidation-resistant alloys and coatings based on γ-TiAl

Fundamental considerations for the development of oxidation-resistant alloys and coatings based on γ-TiAl

Influence of surface finish and annealing treatment on oxidation behavior of Ti-48Al-8Cr-2Ag alloy

Nanometric multilayers: A new approach for joining TiAl

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