Creep behaviour and related high temperature microstructural stability of Ti–46Al–9Nb sheet material

Bystrzanowski, S.; Bartels, A.; Clemens, Helmut; Gerling, R.; Schimansky, F.P.; Dehm, Gerhard; Kestler, H.

doi:10.1016/j.intermet.2004.09.001

Cited by 87 publications

(41 citation statements)

References 28 publications

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“…Similar conclusions have been drawn by [17][18][19][20][21]. On the other hand, in the coarsegrained sample A before DRX, creep is dominated by dislocation climb with a stress exponent of 4.2 [22].…”

Section: Resultssupporting

confidence: 80%

High strain torsion of a TiAl-based alloy

Cao

Klöden

Rybacki

et al. 2008

Materials Science and Engineering: A

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A two-phase lamellar and globular TiAl-based alloy Nb, Ta, B)) with different textures has been deformed in torsion in a Paterson-type rock deformation machine at a temperature of 1173 K under 400 MPa argon confining pressure. The shear stress -shear strain curves with increasing shear strain show a decrease or increase of shear stress in the lamellar and globular case, respectively, to a common steady state value. Activation analysis at high strains yields stress exponents of about 1.8 and an activation energy of 3.29 eV. With increasing shear strain the lamellar structure breaks down and a two-phase fine-grained globular structure develops by recrystallization with a grain size in the order of 2 microns. The weak initial fibre textures at high strains are randomized. The mechanical, microstructural and textural features indicate a transition from dislocation creep to superplastic flow.

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Section: Resultssupporting

confidence: 80%

High strain torsion of a TiAl-based alloy

Cao

Klöden

Rybacki

et al. 2008

Materials Science and Engineering: A

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“…25) Moreover, similar work on TiAl alloy with a high Nb content shows that a stress exponent of about four under a creep condition of 988-1078 K/150-225 MPa is a creep behavior governed by dislocation climb. 14,26) Consequently, the controlling mechanism for creep behavior of Ti40Al-16Nb and Ti-40Al-16Nb-0.4Sc alloys under test conditions herein is dislocation climb.…”

Section: Creep Behaviormentioning

confidence: 87%

Creep Behavior of Ti–40Al–16Nb Intermetallic Alloy and Strengthening Effects of Minor Sc

Zhan

Koo

2006

Mater. Trans.

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The creep behavior of the Ti-40Al-16Nb alloy and the effect of the minor addition of Sc are investigated by creep tests at 1073 K under constant load from 200 to 280 MPa. The creep curve of the alloy with high Nb contents does not exhibit a steady-state region, and the minor addition of Sc added to the alloy has no effect on minimum creep rate. The creep responses of the alloys with high Nb contents are strongly correlated with tertiary creep behavior. The effects of Sc addition are apparent on the properties of tertiary creep rate and rupture life. The tertiary creep rate of the Sc containing alloy is reduced and the creep fracture life is increased. Subgrain structures of dislocations are absent in the alloys with high Nb contents during secondary creep, and the deformation of creep converges mainly at the B2 phase. A stress exponent of 4.5 estimated indicates that the mechanism of controlling creep behavior is dislocation climb. The creep fracture of the alloys is dominated by cleavage fracture over the entire fracture surface. Sc 2 O 3 particles are an effective obstacle to the propagation of cracks and the motion of dislocations.

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“…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].…”

Section: Introductionmentioning

confidence: 99%

“…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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Creep behaviour and related high temperature microstructural stability of Ti–46Al–9Nb sheet material

Cited by 87 publications

References 28 publications

High strain torsion of a TiAl-based alloy

High strain torsion of a TiAl-based alloy

Creep Behavior of Ti–40Al–16Nb Intermetallic Alloy and Strengthening Effects of Minor Sc

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

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Creep behaviour and related high temperature microstructural stability of Ti–46Al–9Nb sheet material

Cited by 87 publications

References 28 publications

High strain torsion of a TiAl-based alloy

High strain torsion of a TiAl-based alloy

Creep Behavior of Ti&ndash;40Al&ndash;16Nb Intermetallic Alloy and Strengthening Effects of Minor Sc

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

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Creep Behavior of Ti–40Al–16Nb Intermetallic Alloy and Strengthening Effects of Minor Sc