Physical constants, deformation twinning, and microcracking of titanium aluminides

Yoo, M.H.; Fu, C. L.

doi:10.1007/s11661-998-0158-2

Cited by 141 publications

(59 citation statements)

References 84 publications

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“…Elastic constants of γ and r-phases have been approximated at 1050°C following He et al (1997);Tanaka (1996);Tang et al (2011);Yoo and Fu (1998), Table 2. For this alloy, C 11 = C 22 , C 23 = C 13 , and C 55 = C 44 .…”

Section: Components Of the Elasticity Tensormentioning

confidence: 99%

Reviewing the class of Al-rich Ti-Al alloys: modeling high temperature plastic anisotropy and asymmetry

Chowdhury

Altenbach

Krüger

et al. 2017

Mech Adv Mater Mod Process

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In the last decades, the class of Ti-rich TiAl-based intermetallic materials has replaced many contemporary alloys till 900°C. Due to higher oxidation resistance, 20% lower density and higher (about 150°C more) operating temperature possibility of Al-rich TiAl alloys over Ti-rich side, phases from the Al-rich region of this alloy system are considered to be highly potential candidates for high temperature structural applications. Although there are a lot of works about Ti-rich alloys, however, investigation from the Al-rich side is very limited. This work reviews the class of Al-rich TiAl alloys in terms of phases, microstructures, morphology, deformation mechanisms, mechanical behaviors along with a possible micromechanical modeling approach. Single crystal like Ti-61.8at.%Al alloy from the Al-rich family has been chosen as an example for modeling high temperature anisotropy and tension-compression asymmetry. A possible comparison with Ti-rich side is also presented.

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Section: Components Of the Elasticity Tensormentioning

confidence: 99%

Reviewing the class of Al-rich Ti-Al alloys: modeling high temperature plastic anisotropy and asymmetry

Chowdhury

Altenbach

Krüger

et al. 2017

Mech Adv Mater Mod Process

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“…is an athermal stress contribution to work hardening due to dislocation accumulation and the formation of sessile dislocation locks (Hemker et al, 1993;Veyssière and J. Douin, 1995;Yoo and Fu, 1998;Appel and Wagner, 1998).…”

Section: Deformation Experimentsmentioning

confidence: 99%

“…Unlike superdislocations, the ordinary dislocations are not dissociated because the complex superlattice stacking fault (CSF) that would be involved in the dissociation has a very high energy (Yoo and Fu, 1998). Thus, the dislocations need not be constricted before cross slipping, which makes the process easier.…”

Section: Jog Dragging and Debris Hardeningmentioning

confidence: 99%

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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“…However, magnesium has certain limitations when compared with other metallic systems and polymers [6]. Since magnesium has a hexagonal close packed (hcp) structure, it has a limited number of active slip systems at room temperature [8,9] which leads to failure in polycrystalline Mg-alloys at ambient conditions before dislocation glide can occur [10][11][12]. In an effort to overcome these low strength shortcomings, recent studies have considered the effects of adding certain alloying elements to magnesium, such as Al-Zn, Al-Si, Al-Ca, Al-Sr, Sn-Ca, Zr-Y, and minute traces of other rare-earth (RE) elements [6,[13][14][15][16][17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Atomic-scale investigation of creep behavior in nanocrystalline Mg and Mg–Y alloys

2015

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Magnesium (Mg) and its alloys offer great potential for reducing vehicular mass and energy consumption due to their inherently low densities. Historically, widespread applicability has been limited by low strength properties compared to other structural Al-, Ti-and Fe-based alloys. However, recent studies have demonstrated high-specific-strength in a number of nanocrystalline Mg-alloys. Even so, applications of these alloys would be restricted to low-temperature automotive components due to microstructural instability under high temperature creep loading. Hence, this work aims to gain a better understanding of creep and associated deformation behavior of columnar nanocrystalline Mg and Mg-yttrium (Y) (up to 3at.%Y(10wt.%Y)) with a grain size of 5 nm and 10 nm. Using molecular dynamics (MD) simulations, nanocrystalline magnesium with and without local concentrations of yttrium is subjected to constant-stress loading ranging from 0 to 500 MPa at different initial temperatures ranging from 473 to 723 K. In pure Mg, the analyses of the diffusion coefficient and energy barrier reveal that at lower temperatures (i.e., T < ~423K) the contribution of grain boundary diffusion to the overall creep deformation is stronger that the contribution of lattice diffusion. However, at higher temperatures (T > ~423K) lattice diffusion dominates the overall creep behavior. Interestingly, for the first time, we have shown that the(101 ̅ 1), (101 ̅ 2),(101 ̅ 3) and (101 ̅ 6) boundary sliding energy is reduced with the addition of yttrium. This softening effect in the presence of yttrium suggests that the experimentally observed high temperature beneficial effects of yttrium addition is likely to be attributed to some combination of other reported creep strengthening mechanisms or phenomena such as formation of stable yttrium oxides at grain boundaries or increased forest dislocation-based hardening.

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Physical constants, deformation twinning, and microcracking of titanium aluminides

Cited by 141 publications

References 84 publications

Reviewing the class of Al-rich Ti-Al alloys: modeling high temperature plastic anisotropy and asymmetry

Reviewing the class of Al-rich Ti-Al alloys: modeling high temperature plastic anisotropy and asymmetry

Role of vacancies in work hardening and fatigue of TiAl alloys

Atomic-scale investigation of creep behavior in nanocrystalline Mg and Mg–Y alloys

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