Effect of niobium on the structure and high-temperature oxidation of TiAl–Ti5Si3 eutectic alloy

Vojtěch, Dalibor; Čížkovský, J.; Novák, Pavel; Šerák, Jan; Fabián, T.

doi:10.1016/j.intermet.2008.04.005

Cited by 26 publications

(14 citation statements)

References 16 publications

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“…In contrast, Nb-enrichment up to about 10% is observed in a thin zone near the scale/metal interface. As indicated before, niobium dissolves preferentially in rutile where it substitutes Ti atoms in their lattice positions, due to the similarity between atomic radii of Ti and Nb [6]. The observed reduction of Nb concentration in the scales towards their surface can be attributed to a significantly slower diffusivity of Nb, as compared to, for example, Al which is present in a relatively high percentage in the whole volume of scales (Figs.…”

Section: Composition Of Scalessupporting

confidence: 53%

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

et al. 2011

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Section: Composition Of Scalessupporting

confidence: 53%

“…Niobium is known to enhance aluminum activity, i.e. its outward diffusion rate, therefore, it supports preferential oxidation of Al to Al 2 O 3 [6]. Alumina present in scales shows a protection against oxygen inward diffusion towards the metallic substrate, because of a very low diffusivity of O in Al 2 O 3 [9].…”

Section: Composition Of Scalesmentioning

confidence: 99%

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

et al. 2011

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“…[5][6][7][8][9][10][11][12][13] The principle of the method is based on the high affinity of silicon and aluminium to titanium. During the immersion of titanium and its alloys in the aluminum melt comprising silicon, a reaction forming a Ti-Al-Si phase at the interface takes place.…”

Section: Introductionmentioning

confidence: 99%

High-temperature oxidation of silicide-aluminide layer on the TiAl6V4 alloy prepared by liquid-phase siliconizing

Kubatík¹

2016

Mater. Tehnol.

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The method of coating with silicon from the liquid phase (also called the hot-dip method) was presented by several authors who indicated that this was an effective and inexpensive technique capable of producing Ti-Al-Si layers on titanium and titanium-alloy substrates that are rich in ternary phases. The present study examines the effects of the preparation conditions on the structure and properties of the layers. These layers provide excellent protection from high-temperature oxidation, even at a temperature of 950°C. It was proved with SEM and X-ray analyses that the original t2 ternary phase almost completely decomposed into pure Ti5Si4 and TiSi silicides at the temperature of 950°C. The formed layer, consisting of silicide sub-layers, exhibited superior protective properties in high-temperature applications. Keywords: TiAl6V4, silicides, high-temperature oxidation, liquid-phase siliconizing Metodo prekrivanja s silicijem iz teko~e faze (v~asih imenovano hot-dip metoda) je predstavilo ve~avtorjev, ki so potrdili, da je to u~inkovita in poceni tehnika, s katero je mogo~e izdelati Ti-Al-Si plasti na podlagi iz titana in titanovih zlitin, ki vsebujejo ternarne faze. Predstavljena {tudija preiskuje vpliv pogojev priprave na strukturo in lastnosti plasti. Te plasti zagotavljajo odli~no za{~ito pred visokotemperaturno oksidacijo, celo pri temperaturi 950°C. S SEM in z rentgensko analizo je bilo dokazano, da se prvotna ternarna faza t2, pri temperaturi 950°C, skoraj v celoti razgradi v~isti Ti5Si4 in TiSi silicid. Nastala plast, ki jo sestavlja ve~podplasti je pokazala odli~ne za{~itne lastnosti pri visokotemperaturni uporabi. Klju~ne besede: TiAl6V4, silicidi, visokotemperaturna oksidacija, silikoniziranje v teko~i fazi

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“…Iron also reduces the grain size of titanium silicides produced by this process [9]. With the exception of the papers dealing with the niobium addition [10], there is a lack of information about the possibilities of the improvement of Ti-Al-Si alloys' properties by the addition of quaternary alloying element. This paper aims to describe the effect of selected transition metals (Cr, Cu, Fe) on microstructure, phase composition, mechanical properties and thermal stability of Ti-Al-Si alloys prepared by reactive sintering.…”

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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Effect of niobium on the structure and high-temperature oxidation of TiAl–Ti5Si3 eutectic alloy

Cited by 26 publications

References 16 publications

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

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

High-temperature oxidation of silicide-aluminide layer on the TiAl6V4 alloy prepared by liquid-phase siliconizing

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

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