Molecular dynamics studies of the roles of microstructure and thermal effects in spallation of aluminum

Liao, Yi; Xiang, Meizhen; Zeng, Xiangguo; Chen, Jun

doi:10.1016/j.mechmat.2015.01.007

Cited by 66 publications

(14 citation statements)

References 57 publications

(64 reference statements)

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“…The lack of publications is due to the difficulties in consolidating NC metals because of their poor thermal microstructural stability as well as overall sample dimensions. Consequently, the vast majority of literature has been devoted to computational modeling efforts of simulated microstructures [18][19][20][21][22][23][24][25][26][27][28][29][30][31] . With regard to the limited experimental studies, the work has utilized laser-driven compression of physically deposited thin films or electrodeposits (<500 µm) 32 .…”

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confidence: 99%

Stable microstructure in a nanocrystalline copper–tantalum alloy during shock loading

et al. 2020

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The microstructures of materials typically undergo significant changes during shock loading, causing failure when higher shock pressures are reached. However, preservation of microstructural and mechanical integrity during shock loading are essential in situations such as space travel, nuclear energy, protection systems, extreme geological events, and transportation. Here, we report ex situ shock behavior of a chemically optimized and microstructurally stable, bulk nanocrystalline copper-tantalum alloy that shows a relatively unchanged microstructure or properties when shock compressed up to 15 GPa. The absence of shockhardening indicates that the grains and grain boundaries that make up the stabilized nanocrystalline microstructure act as stable sinks, thereby annihilating deformation-induced defects during shock loading. This study helps to advance the possibility of developing advanced structural materials for extreme applications where shock loading occurs.

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confidence: 99%

Stable microstructure in a nanocrystalline copper–tantalum alloy during shock loading

et al. 2020

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“…The atomic interactions in Al are described by an accurate embedded atom method (EAM) potential developed by Winey et al [30]. The validity of the EAM potential under strong shock conditions is confirmed by comparing Hugoniot curves (P-V and P-T curves) and the melting curve with experimental data in our previous work [31]. orientations are in accordance with the X1, X2, and X3 coordinate axes of the 3D…”

Section: Introductionmentioning

confidence: 63%

Shock responses of nanoporous aluminum by molecular dynamics simulations

Xiang

Cui

Yang

et al. 2017

International Journal of Plasticity

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Abstract:We present systematic investigations on the shock responses of nanoporous aluminum (np-Al) by nonequilibrium molecular dynamics simulations. The dislocation nucleation sites are found to concentrate in low latitude region near the equator of the spherical void surfaces. We propose a continuum wave reflection theory and a resolved shear stress model to explain the distribution of dislocation nucleation sites. The simulations reveals two mechanisms of void collapse: the plasticity mechanism and the internal jetting mechanism. The plasticity mechanism, which leads to transverse collapse of voids, prevails under relatively weaker shocks; while the internal jetting mechanism, which leads to longitudinal filling of the void vacuum, plays more significant role as the shock intensity increases. In addition, an abnormal thermodynamic phenomenon (i.e., arising of temperature with pressure dropping) in shocked np-Al is discovered. This phenomenon is incompatible with the conventional Rankine-Hugoniot theory, and is explained by the nonequilibrium processes involved in void collapse. The influences of void collapse on spall fracture of np-Al is studied. Under the same loading velocity, the spall strength of np-Al is found to be lower than that of single-crystal Al; but the spall resistance is higher in np-Al than in single-crystal Al. This is explained by the combined influences of thermal dissipation and stress attenuation during shock wave propagation in np-Al.

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“…Simulations reported are performed for aluminum (Al), with interatomic interaction described by the embedded-atom method (EAM) in the form suggested in Ref [9]. Some of the properties of the EAM Al material relevant to the melting process are given in Ref [10]. Prior to simulations, the lattice constant for bulk crystal is determined as a function of temperature.…”

Section: Molecular Simulations and Continuum Modelingmentioning

confidence: 99%

Heterogeneous melting kinetics in polycrystalline aluminum

et al. 2020

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The heterogeneous melting kinetics of polycrystalline aluminum is investigated by a theoretical model which represents the overall melting rate as a functional of the Weibull grain-sizedistribution. It is found that the melting process is strongly affected by the mean-grain-diameter, but is insensitive to the shape parameter of the Weibull distribution. The temperaturetime-transformation (TTT) diagrams are calculated to probe dependence of the characteristic timescale of melting on the overheating temperature and the mean-grain-diameter. The model predicts that the heterogeneous melting time of polycrystalline aluminum exponentially depends on temperature in high temperature range and the exponent constant is an intrinsic material constant independent of the mean-grain-diameter. Comparisons between TTT diagrams of heterogeneous melting and homogenous melting are also provided.

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Molecular dynamics studies of the roles of microstructure and thermal effects in spallation of aluminum

Cited by 66 publications

References 57 publications

Stable microstructure in a nanocrystalline copper–tantalum alloy during shock loading

Stable microstructure in a nanocrystalline copper–tantalum alloy during shock loading

Shock responses of nanoporous aluminum by molecular dynamics simulations

Heterogeneous melting kinetics in polycrystalline aluminum

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