Growth and collapse of nanovoids in tantalum monocrystals

Tang, Yizhe; Bringa, Eduardo M.; Remington, B. A.; Meyers, Marc A.

doi:10.1016/j.actamat.2010.11.001

Cited by 88 publications

(87 citation statements)

References 72 publications

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“…[18][19][20] The current study seeks to evaluate the failure process of tantalum under low rate loading at room temperature both as a means to understand the material's reliability for applications where these environments are relevant, and as a point of departure to later examine highertemperature behavior. Tantalum possesses good ductility at room temperature and maintains modest ductility even down to cryogenic temperatures.…”

Section: Introductionmentioning

confidence: 99%

The Morphology of Tensile Failure in Tantalum

Boyce

Clark

et al. 2013

Metall Mater Trans A

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The deformation, crack nucleation, coalescence, and rupture process of pure tantalum (99.9 pct) were studied under room temperature quasistatic loading using several in situ and ex-situ techniques including optical metallography, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission-electron microscopy (TEM). The fracture surface of tantalum forms a ridge-and-valley morphology that is distinct from conventional notions of ductile dimple microvoid coalescence, and also distinct from spall damage formed during dynamic shock conditions. Failure proceeds by void nucleation at a dislocation cell wall or in subgrain interiors. Coalescence appears to involve a two-stage damage progression: first individual voids coalesce along the tensile axis forming diamond-shaped multivoid cavities; then cavities link-up by intercavity necking. Final rupture occurs when the intercavity necks thin tõ 100-nm films and fail by crystallographic cleavage. This final tearing process was observed using in situ TEM tensile deformation of a thin tantalum film. The detailed microstructural and morphological observations of the current study can be used to guide the development of improved models for tearing of ductile metals.

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Section: Introductionmentioning

confidence: 99%

The Morphology of Tensile Failure in Tantalum

Boyce

Clark

et al. 2013

Metall Mater Trans A

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“…Moreover, despite that defects have signicant effects on dynamic materials properties and processes, [15][16][17][18] including high strain rate loading, studies along this line on MgO are rare. On the one hand, high level concentration of vacancies will form in materials serviced under extreme environment due to the irradiation of neutrons or highenergy particles.…”

Section: Introductionmentioning

confidence: 99%

Schottky defects induced effects on the behaviors of high velocity shock compression of MgO

et al. 2017

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Molecular dynamics (MD) simulation was performed on high velocity plane shock compression of sodium chloride MgO along [100] lattice direction using a long-range coulombic potential. It was found that the shock compressions of MgO revealed three distinct regions depending on piston velocities, i.e., single elastic shock wave, two-wave structure consisting of an elastic wave followed by a plastic deformation wave, and single plastic deformation shock wave. The critical pressure of 120 GPa was obtained for the transition from elastic to plastic deformation under the high strain rate of 10 10 s À1. For getting a better understanding the experimental results, we also investigated the effects of Schottky defects in MgO single crystal on the Hugoniot Elastic Limit (HEL), the velocity of shock wave and the critical piston velocity (CPV) resulting in plastic deformation. Our results demonstrated that the HEL decreases from 120 GPa to 100 GPa, and the CPV decreases a little from 2.8 km s À1 to 2.2 km s À1. Significantly, a double yielding phenomenon occurs for shock wave propagating in MgO sample with Schottky defects, i.e., homogeneous nucleation of dislocations accompanied by vacancy emission of dislocations, which has never been reported before. This work helps to clarify the contradictory results of HEL of MgO in the literature and to understand the plastic deformation mechanism of MgO.

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“…27 Interacting of multiple voids was also found to decrease the stress required for the onset of plasticity under adiabatic uniaxial compression, compared to that for isolated void. [34][35][36][37]39 However, the scaling laws and the underlying atomistic mechanisms of nanoporous metals under adiabatic uniaxial strain compression are still open to further investigations. In this regards, the focus of this paper is to understand the effects of the relative density and the void diameter on the adiabatic uniaxial compression behaviors and the related atomic-level deformation mechanisms in nanoporous copper using MD simulations.…”

Section: Introductionmentioning

confidence: 99%

“…[25][26][27][28] Previous MD simulations have been conducted to investigate the collapse of a single nanovoid or a collection of nanovoids in both fcc and bcc metals at high strain rates. 27,[29][30][31][32][33][34][35][36][37][38][39] These studies have focused on dislocation activities and the resulting porosity evolution in nanoporous metals. Under high rate loading, the void surfaces were found to be dislocation sources, and their collective interaction leading to very high dislocation densities.…”

Section: Introductionmentioning

confidence: 99%

Scaling laws and deformation mechanisms of nanoporous copper under adiabatic uniaxial strain compression

Yuan

2014

AIP Advances

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A series of large-scale molecular dynamics simulations were conducted to investigate the scaling laws and the related atomistic deformation mechanisms of Cu monocrystal samples containing randomly placed nanovoids under adiabatic uniaxial strain compression. At onset of yielding, plastic deformation is accommodated by dislocations emitted from void surfaces as shear loops. The collapse of voids are observed by continuous emissions of dislocations from void surfaces and their interactions with further plastic deformation. The simulation results also suggest that the effect modulus, the yield stress and the energy aborption density of samples under uniaxial strain are linearly proportional to the relative density ρ. Moreover, the yield stress, the average flow stress and the energy aborption density of samples with the same relative density show a strong dependence on the void diameter d, expressed by exponential relations with decay coefficients much higher than -1/2. The corresponding atomistic mechanisms for scaling laws of the relative density and the void diameter were also presented. The present results should provide insights for understanding deformation mechanisms of nanoporous metals under extreme conditions.

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Growth and collapse of nanovoids in tantalum monocrystals

Cited by 88 publications

References 72 publications

The Morphology of Tensile Failure in Tantalum

The Morphology of Tensile Failure in Tantalum

Schottky defects induced effects on the behaviors of high velocity shock compression of MgO

Scaling laws and deformation mechanisms of nanoporous copper under adiabatic uniaxial strain compression

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