Thermomechanical fatigue behaviour of a third generation γ-TiAl intermetallic alloy

Bauer, V.; Christ, Hans‐Jürgen

doi:10.1016/j.intermet.2008.11.013

Cited by 43 publications

(24 citation statements)

References 18 publications

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“…Thus, the reduced TMF performance under OP conditions has to be attributed to the influence of tensile mean stress and environmental effect, which promote the rapid initiation of fatigue cracks. These results are in good accordance with the observations presented in [3], which were obtained on the alloy TNB-V5. The development of mean stress for all TMF tests conducted is represented in Fig.…”

Section: Influence Of Environmentsupporting

confidence: 93%

“…This manifests itself in longer lifetimes at higher temperatures if detrimental effects of air are excluded. Results of LCF tests on TNB-V5 (Ti-45Al-5Nb) support the trend in ratios between fatigue lives in air and vacuum at 650 and 750°C [3]. At 850°C, however, a decrease in lifetime is observed again.…”

Section: Influence Of Environmentsupporting

confidence: 65%

“…This alloy belongs to the so-called 3rd generation γ-TiAl based alloys with a high content of niobium [1]. Previous investigations on a similar alloy, TNB-V5, have indicated the superiority in terms of fatigue strength of this TiAl class compared to earlier generations [2][3][4]. However, today's alloys still cannot fulfil their full potential since they lack sufficient oxidation resistance at temperatures greater than 700°C (1300°F).…”

Section: Introductionmentioning

confidence: 99%

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Thermomechanical Fatigue of the TiAl Intermetallic Alloy TNB-V2

Heckel

Christ

2009

Exp Mech

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TiAl is supposed to substitute Ni or Ti alloys in energy conversion systems, such as aero engines. These components are subjected to thermomechanical fatigue (TMF), whereas this mechanical behaviour may substantially differ from isothermal low cycle fatigue (LCF). Therefore, it is necessary to assess TMF properties, in order to establish a reliable and precise lifetime prediction model. In this study the γ-base TiAl intermetallic alloy TNB-V2 was subjected to fully-reversed TMF tests under total strain control at strain amplitude of 0.7%, accompanied by LCF tests in air and vacuum. Temperature ranged from 550°C to 850°C. In TMF tests a continuous built-up of compressive (in-phase) or tensile (out-of-phase) mean stresses is observed. The lifetime ratio between IP and OP is 30-200, depending on temperature range. Substantially longer lifetimes of OP-TMF tests in vacuum are observed. Fracture always occurs in a transcrystalline mode. A lifetime description at 550°C based on the BasquinCoffin-Manson equation reveals that the fatigue behaviour is governed by the amount of elastic strain even at low cycles, and the transition lifetime was found to be at 5 cycles. A damage parameter based on the equation of Smith, Watson and Topper is able to describe LCF and inphase TMF lifetimes reasonably.

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Section: Influence Of Environmentsupporting

confidence: 93%

Section: Influence Of Environmentsupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

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Thermomechanical Fatigue of the TiAl Intermetallic Alloy TNB-V2

Heckel

Christ

2009

Exp Mech

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“…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.…”

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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“…Christ et al studied the influence of temperature, environment, and temperature-strain cycle (IP and OP) on the TMF behavior of the c-TiAl alloys XD 47-2-2, [15][16][17] c-MET, and c-PX [13,14,[18][19][20][21] in the temperature range from 450°C to 800°C. Skrotzki et al studied the TMF behavior of TNB-V5 under axial (IP and OP) and axial-torsional loading conditions in the temperature range 400°C to 800°C.…”

Section: Introductionmentioning

confidence: 99%

Thermomechanical Fatigue Behavior of the Intermetallic γ-TiAl Alloy TNB-V5 with Different Microstructures

Roth

Biermann

2010

Metall Mater Trans A

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The cyclic deformation and fatigue behavior of the c-TiAl alloy TNB-V5 is evaluated under thermomechanical load for three different microstructures. For this purpose, strain-controlled thermomechanical fatigue (TMF) tests were carried out with different temperature-strain cycles, different temperature ranges from 400°C to 800°C (673 K to 1073 K), and with two different strain ranges to set a fatigue-life relation. Cyclic deformation curves, stress-strain hysteresis loops, and fatigue lives of the tests are presented. The microstructures near-gamma (NG) and duplex (DP) show comparable fatigue lives under all test parameters. The microstructure fullylamellar (FL) offers longer fatigue lives at the same loading conditions. For a general life prediction, the damage parameter of Smith, Watson, and Topper, P SWT vs fatigue life, is well suitable, if the testing and the application temperature ranges, respectively, include temperatures above the ductile-brittle transition (approximately 750°C). In the completely brittle material behavior regime the quality of the lifetime prediction is unacceptable. The damage parameter P HL by Haibach and Lehrke shows a comparable correlation to the fatigue life as P SWT . The results are discussed with microstructural investigations.

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Thermomechanical fatigue behaviour of a third generation γ-TiAl intermetallic alloy

Cited by 43 publications

References 18 publications

Thermomechanical Fatigue of the TiAl Intermetallic Alloy TNB-V2

Thermomechanical Fatigue of the TiAl Intermetallic Alloy TNB-V2

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

Thermomechanical Fatigue Behavior of the Intermetallic γ-TiAl Alloy TNB-V5 with Different Microstructures

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