Molecular dynamics simulations of void shrinkage in γ-TiAl single crystal

Xu, Ximing; Tang, Fuling; Han, Xue; Yu, Wei-Yuan; Zhu, Liang; Zhou, Rui

doi:10.1016/j.commatsci.2015.05.007

Cited by 23 publications

(3 citation statements)

References 35 publications

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“…The direction of macroscopic loading can lead to the shrinkage of existing voids. Xu et al [132] studied nano-voids within a γ-TiAl matrix under uniaxial compression and reported three stages in the shrinkage process. In the first stage, i.e., elastic deformation, the void was shown to shrink along the loading direction while expanding in the transverse direction.…”

Section: Void Nucleation and Growth Mechanisms At Nano-and Sub-micron...mentioning

confidence: 99%

Void Nucleation and Growth from Heterophases and the Exploitation of New Toughening Mechanisms in Metals

2023

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Heterophases, such as precipitates, inclusions, second phases, or reinforcement particles, often drive void nucleation due to local incompatibilities in stresses/strains. This results in a significant life-limiting condition, as voids or their coalescence can lead to microcracks that reduce the ductility and fatigue life of engineering components. Continuum-mechanics-based analytical models have historically gained momentum due to their relative ease in predicting failure strain. The momentum of such treatment has far outpaced the development of theories at the atomic and micron scales, resulting in an insufficient understanding of the physical processes of void nucleation and growth. Evidence from the recent developments in void growth theories indicates that the evolution of voids is intrinsically linked to dislocation activity at the void–matrix interface. This physical growth mechanism opens up a new methodology for improving mechanical properties using hydrostatic pressurization. According to the limited literature, with a hydrostatic pressure close to 1 GPa, aluminium matrix composites can be made 70 times more ductile. This significant ductility enhancement arises from the formation of dislocation shells that encapsulate the heterophases and inhibit the void growth and coalescence. With further investigations into the underlying theories and developments of methods for industrial implementations, hydrostatic pressurization has the potential to evolve into an effective new method for improving the ductility and fatigue life of engineering components with further development.

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Section: Void Nucleation and Growth Mechanisms At Nano-and Sub-micron...mentioning

confidence: 99%

Void Nucleation and Growth from Heterophases and the Exploitation of New Toughening Mechanisms in Metals

2023

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“…It has been proved to be reliable, e.g. the EAM has been used to study void shrinkage in γ-TiAl single crystal [25].…”

Section: Model and Interatomic Potentialmentioning

confidence: 99%

The effect of residual stress on Σ3(111) twin boundaries fracture behavior in γ-TiAl with molecular dynamics simulation

Feng

Song

et al. 2019

Modelling Simul. Mater. Sci. Eng.

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In this paper, molecular dynamics (MD) simulations are performed to study the influence of residual stress on fracture behavior in γ-TiAl alloy with ∑3(111) twin boundaries. The tensile processes are simulated at 1, 300, 1050 K after the residual stress is introduced by prepressing. The evolution of microdefects during tensile fracture is observed, and the distribution of residual stress in three direction is characterized. Results show that the introduced residual stress is symmetrically distributed on both sides of ∑3(111) twin boundaries. The residual compressive stress can prevent the nucleation of micro-cracks and increase the yield strength. The fracture mode of the γ-TiAl alloy with ∑3(111) twin boundaries during tensile load at 1 K is the nucleation of microcracks at grain boundaries followed by intergranular fracture. The ∑3(111) twin boundaries have good thermal stability. The residual compressive stress is completely released and the amplitude of residual tensile stress increases at 1050 K, and the γ-TiAl alloy with ∑3(111) twin boundaries exhibits good ductility.

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“…The atomistic pathway of void collapse mechanisms under uniaxial loading in fcc [ 26 , 27 , 36 ] and bcc [ 37 ] metals are investigated in the previous works. Other reports, such as that of Xu et al [ 38 ], analyzed the dependency of the specimen size, strain rate and the initial void volume fraction on the void collapse for

-TiAl single crystals. Zhang et al [ 39 ] investigated the influence of void density on the dislocation mechanism responsible for void shrinkage in nickel single crystals.…”

Section: Introductionmentioning

confidence: 99%

Influence of Temperature on Void Collapse in Single Crystal Nickel under Hydrostatic Compression

et al. 2021

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Employing atomistic simulations, we investigated the void collapse mechanisms in single crystal Ni during hydrostatic compression and explored how the atomistic mechanisms of void collapse are influenced by temperature. Our results suggest that the emission and associated mutual interactions of dislocation loops around the void is the primary mechanism of void collapse, irrespective of the temperature. The rate of void collapse is almost insensitive to the temperature, and the process is not thermally activated until a high temperature (∼1200–1500 K) is reached. Our simulations reveal that, at elevated temperatures, dislocation motion is assisted by vacancy diffusion and consequently the void is observed to collapse continuously without showing appreciable strain hardening around it. In contrast, at low and ambient temperatures (1 and 300 K), void collapse is delayed after an initial stage of closure due to significant strain hardening around the void. Furthermore, we observe that the dislocation network produced during void collapse remains the sample even after complete void collapse, as was observed in a recent experiment of nickel-base superalloy after hot isostatic pressing.

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Molecular dynamics simulations of void shrinkage in γ-TiAl single crystal

Cited by 23 publications

References 35 publications

Void Nucleation and Growth from Heterophases and the Exploitation of New Toughening Mechanisms in Metals

Void Nucleation and Growth from Heterophases and the Exploitation of New Toughening Mechanisms in Metals

The effect of residual stress on Σ3(111) twin boundaries fracture behavior in γ-TiAl with molecular dynamics simulation

Influence of Temperature on Void Collapse in Single Crystal Nickel under Hydrostatic Compression

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