Creep deformation in two-phase titanium aluminide alloys

Appel, F.; Christoph, U.; Oehring, Michael

doi:10.1016/s0921-5093(01)01633-1

Cited by 47 publications

(27 citation statements)

References 23 publications

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“…[20][21][22][23] The essence of the arguments is that the phase separation upon cooling described by the phase diagram often cannot be established within the constraints of processing routes, because the kinetics of the transformation is sluggish. [24,25] This can result in significant fractions of Ti Al antisite defects. At a sufficiently high concentration, the antisite defects form a percolating substructure of antistructural bridges along which long-range diffusion can occur.…”

Section: A Effects Of Phase Constitution On the Evolution Of The Micmentioning

confidence: 99%

Microstructural evolution during hot working of ti aluminide alloys: Influence of phase constitution and initial casting texture

Imayev

Oehring³

et al. 2005

Metall Mater Trans A

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The hot-working behavior of ␥(TiAl)-based alloys was investigated in order to understand fundamental aspects of the evolution of the microstructure and to establish guidelines for advanced alloy design and processing. The investigations involved a wide range of Al compositions and are based on metallographic investigations of the deformed samples. Particular emphasis was placed on the effects of phase composition and casting texture. It was found that the behavior of dynamic recrystallization was significantly influenced by the Al content of the alloys. Under the same deformation conditions, dynamic recrystallization was fastest for alloys with nearly stoichiometric composition, whereas the recrystallization kinetics decreased for lower or higher Al contents. This result can be attributed to the effect of the Al concentration on the micromechanisms of deformation and diffusion as well as on the initial cast microstructure, which changed from fully lamellar to equiaxed near-␥ microstructures by raising the Al content from 45 to 50 at. pct. Further, it was observed that the casting texture, i.e., the orientation of lamellae with respect to the deformation axis, significantly influenced the recrystallization behavior. In this respect, the development of shear bands due to kinking and bending of lamellae is concluded to play an important role in the recrystallization behavior and seems, in general, to be a particular feature of the microstructural evolution of lamellar alloys on hot working.

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Section: A Effects Of Phase Constitution On the Evolution Of The Micmentioning

confidence: 99%

Microstructural evolution during hot working of ti aluminide alloys: Influence of phase constitution and initial casting texture

Imayev

Oehring³

et al. 2005

Metall Mater Trans A

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“…Microstructural instabilities have also been reported to occur at high temperatures. [3,15,17] At temperatures above 923 K (650°C) (T > 0.4T m ), c-TiAl alloys are susceptible to creep. These materials usually exhibit a limited secondary-creep region, characterized by the absence of a steady state, in which the creep rate reaches a minimum and then increases with strain leading to the tertiary stage.…”

Section: Introductionmentioning

confidence: 99%

Effect of Stress Level on the High Temperature Deformation and Fracture Mechanisms of Ti-45Al-2Nb-2Mn-0.8 vol. pct TiB2: An In Situ Experimental Study

Muñoz‐Moreno

Pérez‐Prado

LLorca

et al. 2012

Metall Mater Trans A

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The effect of the applied stress on the deformation and crack nucleation and propagation mechanisms of a c-TiAl intermetallic alloy (Ti-45Al-2Nb-2Mn (at. pct)-0.8 vol. pct TiB 2 ) was examined by means of in situ tensile (constant strain rate) and tensile-creep (constant load) experiments performed at 973 K (700°C) using a scanning electron microscope. Colony boundary cracking developed during the secondary stage in creep tests at 300 and 400 MPa and during the tertiary stage of the creep tests performed at higher stresses. Colony boundary cracking was also observed in the constant strain rate tensile test. Interlamellar ledges were only found during the tensile-creep tests at high stresses (r > 400 MPa) and during the constant strain rate tensile test. Quantitative measurements of the nature of the crack propagation path along secondary cracks and along the primary crack indicated that colony boundaries were preferential sites for crack propagation under all the conditions investigated. The frequency of interlamellar cracking increased with stress, but this fracture mechanism was always of secondary importance. Translamellar cracking was only observed along the primary crack.

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“…c phase transformation has been observed during long-term creep since the microstructure of the initial materials is in non-equilibrium [25,26]. Thus, the transformation needs both a change of stacking sequence and change of composition (by diffusion) [27]. It was suggested that dislocations, stacking faults, grain boundaries, and other structural defects are preferential sites for the nucleation of martensite [28].…”

Section: Torsion-induced Phase Transformationmentioning

confidence: 99%

Microstructural evolution of TiAl-based alloys deformed by high-pressure torsion

et al. 2015

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Creep deformation in two-phase titanium aluminide alloys

Cited by 47 publications

References 23 publications

Microstructural evolution during hot working of ti aluminide alloys: Influence of phase constitution and initial casting texture

Microstructural evolution during hot working of ti aluminide alloys: Influence of phase constitution and initial casting texture

Effect of Stress Level on the High Temperature Deformation and Fracture Mechanisms of Ti-45Al-2Nb-2Mn-0.8 vol. pct TiB2: An In Situ Experimental Study

Microstructural evolution of TiAl-based alloys deformed by high-pressure torsion

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