Electron microscope characterization of low cycle fatigue in a high-strength multiphase titanium aluminide alloy

Appel, F.; Heckel, Thomas; Christ, Hans‐Jürgen

doi:10.1016/j.ijfatigue.2009.04.001

Cited by 40 publications

(22 citation statements)

References 16 publications

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“…For example, during room temperature cycling, the tensile stress amplitude increased during 641 cycles from 935 to 1050 MPa. Failure typically occurred after N f =500 to 645 cycles, depending on test temperature (Appel et al, 2010). This observation essentially coincides with the data reported in the literature for different other…”

Section: Fatigue Structuressupporting

confidence: 90%

“…Thus, recovery of fatigue structures seems to be more complex. Nevertheless, the observations may explain why in samples fatigued at 850 °C dipoles and debris are completely absent (Appel et al, 2010). At this temperature dynamic recovery has probably fully taken place, which is consistent with the cycling softening observed at this temperature.…”

Section: Recovery Of Fatigue Structuressupporting

confidence: 82%

“…In previous studies Appel et al, 2010;El-Chaikh et al, 2011), the fatigue performance of the high-strength alloy #2b with composition Ti-45Al-8Nb-0.2C was investigated. Fully reversed isothermal tests were performed under strain control at temperatures of 25 °C, 550 °C and 850 °C and a total (elastic plus plastic) strain amplitude of 2 0.7%…”

Section: Low-cycle Fatiguementioning

confidence: 99%

“…Several aspects of work hardening under monotonic loading might also be important for the fatigue performance of the material. Indeed, depending on the test conditions, a TiAl specimen may cyclically harden, cyclically soften or maintain its flow stress (Hénaff and Gloanec, 2005;Heckel and Christ, 2010;Appel et al, 2010;El-Chaikh et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Role of vacancies in work hardening and fatigue of TiAl alloys

Appel

Herrmann

Fischer

et al. 2013

International Journal of Plasticity

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The role of vacancies in work hardening and fatigue of TiAl alloys was investigated by mechanical testing and TEM examination of deformed samples. The evolution of the dislocation glide resistance during straining and after recovery was analyzed in terms of thermodynamic glide parameters. Strain path change tests with respect to temperature and recovery experiments were performed in order to characterize the thermal stability of the produced defect structures. The recovery of the deformation induced defect structure was observed by TEM in situ heating experiments. The recovery kinetics is described on the basis of a recently published simulation study of vacancy annihilation.

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Section: Fatigue Structuressupporting

confidence: 90%

Section: Recovery Of Fatigue Structuressupporting

confidence: 82%

Section: Low-cycle Fatiguementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Role of vacancies in work hardening and fatigue of TiAl alloys

Appel

Herrmann

Fischer

et al. 2013

International Journal of Plasticity

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“…The calculated G/B ratios of B19 TiAl from the EDM is 10.03% and 14.18% lower than the theoretical data of γ-TiAl (0.62) and α 2 -Ti 3 Al (0.65) [42], respectively, indicating that B19 TiAl is more ductile than γ-TiAl and α 2 -Ti 3 Al. Experimentally, Appel et al [3,[8][9][10] have measured the mechanical properties of γ-TiAl-based intermetallics with the microstructure containing B19 phase and found that the existence of B19 structure can give the intermetallics relatively high tensile ductility. According to Pettifor's rule [12], a material has more metallic (angular) bonds and thus is more ductile (brittle) if it has a larger positive (negative) Cauchy pressure.…”

Section: Elastic and Mechanical Propertiesmentioning

confidence: 99%

Ab Initio Study of the Elastic and Mechanical Properties of B19 TiAl

et al. 2017

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Abstract:A theoretical study of the structural, elastic, and mechanical properties of B19 TiAl intermetallic compound with orthorhombic structure has been carried out by using ab initio density functional theory calculations based on the projector augmented wave and the generalized gradient approximation. The optimized structure parameters are found to be in agreement with the available experimental data. The orthorhombic B19 structure of TiAl is found to be mechanically stable at ground state in terms of formation energy and single crystal elastic constants. Additionally, the polycrystalline bulk, shear and Young's moduli, Poisson's ratio, Cauchy pressure, and anisotropy factors are obtained from the single crystal elastic constants. At ground state, the B19 TiAl is found to not only have intrinsic brittleness in terms of Pugh's ratio, Poisson's ratio, and Cauchy pressure, but also exhibit elastic anisotropy in terms of elastic anisotropy factors and orientation dependence of Young's modulus.

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TiAl Intermetallics

Appel

2010

Encyclopedia of Aerospace Engineering

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Intermetallic titanium aluminides offer an attractive combination of low density and good oxidation and ignition resistance with unique mechanical properties. Thus, they are one of the few classes of emerging materials that have the potential to be used in demanding high‐temperature structural applications whenever specific strength and stiffness are of major concern. Advanced TiAl alloys have very complex microstructures with important features at the nanometer scale. There is an intimate correlation between the alloy chemistry, constitution, microstructure, and mechanical properties, which has to be considered in order to meet the desired properties. These concerns are addressed in this chapter through a global commentary on the physical metallurgy of TiAl‐based alloys. Particular emphasis is paid on recent developments of TiAl alloys with enhanced high‐temperature capability for application in aeroengines. Since TiAl alloys are now at the point of application, this chapter serves the materials' engineers as guidance in the huge body of literature concerning gamma titanium aluminide alloys going back nearly 20 years.

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Electron microscope characterization of low cycle fatigue in a high-strength multiphase titanium aluminide alloy

Cited by 40 publications

References 16 publications

Role of vacancies in work hardening and fatigue of TiAl alloys

Role of vacancies in work hardening and fatigue of TiAl alloys

Ab Initio Study of the Elastic and Mechanical Properties of B19 TiAl

TiAl Intermetallics

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