Comparison of Nb- and Ta-effectiveness for improvement of the cyclic oxidation resistance of TiAl-based intermetallics

Vojtěch, Dalibor; Popela, T.; Kubásek, Jiří; Maixner, J.; Novák, Pavel

doi:10.1016/j.intermet.2010.11.025

Cited by 69 publications

(23 citation statements)

References 26 publications

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“…The correlation coefficients of these fits r 2 are better than 0.96. As shown by Mitoraj and Godlewska [12] for Ti-46Al-8Ta (at.%), Luo et al [16] for Ti--46.5Al-3Ta-2Cr-0.2W (at.%) and Vojtěch et al [14] for Ti-44.8Al-6.6Ta (at.%) alloys, early stages of the oxidation follow the linear kinetic model with a constant of n = 1 indicating that the forming oxidation scale is not protective. The similar sharp linear increase of the oxidation rate is also observed in the sample oxidized at 800…”

Section: Oxidation Kineticsmentioning

confidence: 82%

“…Since the experimental data taken from the work [12] are highly dispersed, the parabolic rate constants k p are only estimated using regression analysis to be 3.136 × 10 iment, sample handling during cyclic oxidation experiments and measurements of the weight gain. Vojtěch et al [14] studied high-temperature cyclic oxidation behaviour of the Ti-44.8Al-6.6Ta (at.%) alloy at 800-1000…”

Section: Oxidation Kineticsmentioning

confidence: 99%

“…• C [12][13][14]. Ta was found to be more effective in terms of increasing high-temperature oxidation resistance than Nb, particularly at 1000…”

Section: Introductionmentioning

confidence: 99%

“…• C [14]. Although all studies describe positive effect of Ta on oxidation resistance of TiAl-based alloys, the experimental results are limited to short oxidation time (up to 380 h) and oxidation kinetics lacks clear explanation due to a large fluctuation of experimental results.…”

Section: Introductionmentioning

confidence: 99%

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Cyclic oxidation behaviour of intermetallic Ti-46Al-8Ta alloy in air

Pelachová¹,

Lapin²

2016

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The cyclic oxidation behaviour of intermetallic Ti-46Al-8Ta (at.%) alloy was studied in the air. Long-term oxidation experiments were carried out on the samples with convoluted type of γ(TiAl) + α2(Ti3Al) microstructure at temperatures ranging from 700 to 800• C for oxidation time up to 3100 h. The oxidation kinetics was determined from the weight gain measurements as a function of oxidation time and temperature. The parabolic rate constants and activation energy for oxidation were calculated and discussed. The experimental results showed that the spallation had no significant effect on oxidation kinetic curves at 700 and 760• C up to 3100 h but affected the measured kinetics at 800• C for oxidation time longer than 500 h. The EDS and X-ray diffraction observations showed that the scales consisted of TiO2, α-Al2O3, Ti2AlN, TaAlTi and TiN phases.K e y w o r d s : titanium aluminides, TiAl, cyclic oxidation, microstructure

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Section: Oxidation Kineticsmentioning

confidence: 82%

Section: Oxidation Kineticsmentioning

confidence: 99%

“…• C [12][13][14]. Ta was found to be more effective in terms of increasing high-temperature oxidation resistance than Nb, particularly at 1000…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cyclic oxidation behaviour of intermetallic Ti-46Al-8Ta alloy in air

Pelachová¹,

Lapin²

2016

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“…To improve the high-temperature oxidation behaviour of these materials, additions of various alloying elements are applied. Previously, it was reported that niobium and tantalum increase the high-temperature oxidation resistance [2] and creep behaviour [3] of Ti-Al alloys. It led to the development of new generation of Ti-Al alloys [4].…”

Section: Introductionmentioning

confidence: 99%

EFFECT OF ALLOYING ELEMENTS ON PROPERTIES OF PM Ti-Al-Si ALLOYS

Novák¹,

Kříž²,

Michalcová³

et al. 2013

Acta Metall Slovaca

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This work was devoted to the description of the effect of alloying by transition metals (Cr, Cu, Fe) on the structure and properties of TiAl15Si15 alloy. Alloying elements does not form separate phases, being dissolved in titanium silicide or aluminide. Cu was found predominantly in aluminide phase, while iron was found to bethe silicide-former. Chromium dissolved in both aluminide and silicide in almost comparable amounts. All applied alloying elements increased the wear resistance, but reduced the room-temperature compression strength. The addition of iron and chromium strongly increase the thermal stability at 1000°C by stabilizing the silicide phase.Keywords: reactive sintering; mechanical properties testing; intermetallic compounds; oxidation 1 Introduction Alloys based on titanium aluminides (Ti 3 Al and TiAl) are modern materials for hightemperature applications. Due to low density, good mechanical properties and oxidation resistance at high temperatures, these alloys already found its application in the aerospace industry. The application limits of Ti 3 Al phase are 760°C in inert atmosphere (creep limit) and approx. 600°C in air (oxidation limit) [1]. Application range of TiAl phase is 750°C in air and approx. 900°C in inert atmosphere or vacuum [1]. It shows that the temperature range of application of all Ti-Al phases is strongly limited by their high-temperature oxidation. To improve the high-temperature oxidation behaviour of these materials, additions of various alloying elements are applied. Previously, it was reported that niobium and tantalum increase the high-temperature oxidation resistance [2] and creep behaviour [3] of Ti-Al alloys. It led to the development of new generation of Ti-Al alloys [4]. However these heavy and expensive elements undesirably increase the density and cost. Other possibility how to improve hightemperature behaviour is alloying with silicon. When Ti-Al-Si alloys are produced by conventional melting metallurgy techniques, coarse sharp-edged particles of Ti 5 Si 3 silicide are formed, having negative impact on mechanical properties such as ductility or fracture toughness. Simple production route leading to the fine structure is a reactive sintering powder metallurgy. In our previous works [5], [6], production route for Ti-Al-Si alloys with aluminium content between 8 and 20 wt. % and silicon in the range of 10-20 wt. % was developed and roomtemperature properties were described [5]. There are many papers dealing with the influence of various alloying elements on the structure and selected properties of Ti-Al and Ti-Si binary alloys. In addition to the effect of Nb and Ta,

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