An electron microscope study of deformation and crack propagation in (α<sub>2</sub>+ γ) titanium aluminides

Appel, F.; Christoph, U.; Wagner, Richard

doi:10.1080/01418619508239929

Cited by 61 publications

(14 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The process was found to be closely related to mismatch structures and coherency stresses present at the semicoherent interfaces. [3,8,18,23,24] The coherency stresses are comparable with the yield stress of the material and give rise to the formation of loop structures adjacent to the interfaces (Fig. 1c).…”

Section: Generation Of Perfect Dislocationsmentioning

confidence: 67%

“…[17] At room temperature multiplication has been found to be closely related to jogs in screw dislocations, which were probably generated by cross slip. [3,18] Possible mechanisms are schematically sketched in Figure 3a. Since the jogs are immobile in the direction of the motion of the screw dislocations, dislocation dipoles are trailed at the jogs.…”

Section: Generation Of Perfect Dislocationsmentioning

confidence: 99%

“…In this context TEM observations of crack tips have been performed on twophase titanium aluminides with different microstructures. [18] Figure 21 demonstrates a high-resolution image of a crack, which propagated in a thin foil of a lamellar alloy. The crack followed {111} c planes which indicates that c-TiAl is prone to cleavage fracture on these planes.…”

Section: Fracture Toughnessmentioning

confidence: 99%

See 2 more Smart Citations

Recent Progress in the Development of Gamma Titanium Aluminide Alloys

Appel¹,

Brossmann²,

Christoph³

et al. 2000

Adv. Eng. Mater.

Self Cite

353

103

View full text Add to dashboard Cite

Intermetallic titanium aluminides offer an attractive combination of low density and good oxidation and ignition resistance with unique mechanical properties. These involve high strength and elastic stiffness with excellent high temperature retention. 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. However, in order to effectively replace the heavier nickel‐base superalloys currently in use, titanium aluminides must combine a wide range of mechanical property capabilities. Advanced alloy designs are tailored for strength, toughness, creep resistance, and environmental stability. These concerns are addressed in the present paper through global commentary on the physical metallurgy and associated processing technologies of γ‐TiAl‐base alloys. Particular emphasis is paid on recent developments of TiAl alloys with enhanced high‐temperature capability.

show abstract

Section: Generation Of Perfect Dislocationsmentioning

confidence: 67%

Section: Generation Of Perfect Dislocationsmentioning

confidence: 99%

Section: Fracture Toughnessmentioning

confidence: 99%

See 1 more Smart Citation

Recent Progress in the Development of Gamma Titanium Aluminide Alloys

Appel¹,

Brossmann²,

Christoph³

et al. 2000

Adv. Eng. Mater.

Self Cite

353

103

View full text Add to dashboard Cite

show abstract

“…It is possible for in situ SEM measurements of stable crack growth to be made with micromechanical methods [105]. However, for meaningful FCG data to be achieved, the plastic zone should be considerably smaller than the testpiece dimensions, and though this is achievable for brittle ceramics [105], the plastic zone radius of γ -TiAl alloys in fatigue is several microns [106], which is at the limit for a micromechanical testpiece.…”

Section: Fatigue Of Polysynthetically Twinned Crystalsmentioning

confidence: 99%

“…The study of the HCF behaviour of γ -TiAl alloys has generally focused on plasticity in the region of a crack tip, rather than in the bulk of the material [66,106]. This is possibly because in common engineering alloys, achieving HCF loading to over 10 7 cycles often means operating at stresses considerably below the yield stress, so that to exceed the local critical resolved shear stress for slip, stress concentration at a crack tip, a hard particle or a crystal boundary is required.…”

Section: Towards a Microscopic Model For Hcf Loading Of Tial Alloys: mentioning

confidence: 99%

Recent progress in the high-cycle fatigue behaviour of γ-TiAl alloys

Edwards

2018

Materials Science and Technology

View full text Add to dashboard Cite

The high-cycle fatigue (HCF) properties of γ -TiAl (gamma titanium aluminide) alloys are reviewed, particularly with regards to the deformation mechanisms active in the near-threshold cyclic loading regime. By examining the influence of lamellar orientation and thickness on the HCF threshold, in addition to more conventional microstructural considerations such as the grain size or the volume fraction of lamellar colonies, factors to improve the γ -TiAl microstructure for HCF are assessed. Finally, experimental methods and loading strategies are surveyed to identify techniques for improving HCF testing of γ -TiAl alloys. In this, we consider both the conservativism of differing approaches and the possibility to measure with suitable resolution the local mechanical behaviour under HCF of the lamellar γ -TiAl microstructure. ARTICLE HISTORY

show abstract