Ultrashort shock waves in nickel induced by femtosecond laser pulses

Demaske, Brian; Zhakhovsky, V. V.; Inogamov, N. A.; Oleynik, Ivan

doi:10.1103/physrevb.87.054109

Cited by 86 publications

(37 citation statements)

References 33 publications

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“…it is the dynamic yield point. The subsequent plastic wave is commonly ascribed to the generation and motion of dislocations, the agents of plasticity in crystalline solids [9].The cause of its attenuation remains unclear after six decades [4][5][6][7][8]. Clifton and Markenscoff [4] calculated analytically the amplitude attenuation of a planar elastic shock wave caused by the destructive interference of elastic wavelets emanating from pre-existing dislocations set into motion by the passage of a shock wave of infinite strain rate; dislocation generation by the shock was neglected.…”

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confidence: 99%

Attenuation of the Dynamic Yield Point of Shocked Aluminum Using Elastodynamic Simulations of Dislocation Dynamics

et al. 2015

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When a metal is subjected to extremely rapid compression, a shock wave is launched that generates dislocations as it propagates. The shock wave evolves into a characteristic two-wave structure, with an elastic wave preceding a plastic front. It has been known for more than six decades that the amplitude of the elastic wave decays the further it travels into the metal: this is known as "the decay of the elastic precursor". The amplitude of the elastic precursor is a dynamic yield point because it marks the transition from elastic to plastic behaviour. In this letter we provide a full explanation of this attenuation using the first method of dislocation dynamics to treat the time dependence of the elastic fields of dislocations explicitly. We show that the decay of the elastic precursor is a result of the interference of the elastic shock wave with elastic waves emanating from dislocations nucleated in the shock front. Our simulations reproduce quantitatively recent experiments on the decay of the elastic precursor in aluminum, and its dependence on strain rate.The dynamic behaviour of crystalline solids subjected to shock compression plays a central role in diverse applications, including bird strikes in aerospace [1], crashworthiness in the automobile industry [2], and manufacturing processes such as laser shock peening [3], amongst many others. Upon being shocked within a range of strain rates and pressures of typically 10 6 − 10 10 s −1 and 5 − 50GPa [1], the shock front in crystalline materials often displays a characteristic two-wave structure near the loading surface: the plastic wave front leading to the Hugoniot shocked state is preceded by an elastic precursor wave [1]. The amplitude of the elastic precursor wave decays as the wave front advances[1, 4]-a phenomenon known as the 'decay of the elastic precursor'. The amplitude of the elastic wave marks the onset of plasticity, i.e. it is the dynamic yield point. The subsequent plastic wave is commonly ascribed to the generation and motion of dislocations, the agents of plasticity in crystalline solids [9].The cause of its attenuation remains unclear after six decades [4][5][6][7][8]. Clifton and Markenscoff [4] calculated analytically the amplitude attenuation of a planar elastic shock wave caused by the destructive interference of elastic wavelets emanating from pre-existing dislocations set into motion by the passage of a shock wave of infinite strain rate; dislocation generation by the shock was neglected. Consequently, the elastic precursor decay was attributed to the density and initial velocity of pre-existing dislocations. Armstrong et al.[10] studied the dislocation relaxation mechanisms during high strain rate shock loading, concluding that dislocation generation dominates plastic relaxation under shock loading. This is because the number of pre-existing dislocations is about two to three orders of magnitude less than that generated during the shock [1,4,7].In this letter we show that we can account for the experimentally observed residual disloca...

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confidence: 99%

Attenuation of the Dynamic Yield Point of Shocked Aluminum Using Elastodynamic Simulations of Dislocation Dynamics

et al. 2015

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“…This is a stage when mainly thermal evolution transfers to mainly mechanical evolution. Profiles of ion thermodynamic parameters T i , E i , p i have kinks [15,19]. Before the transition those kinks "sit" at the points of solidus and liquidus.…”

Section: Model and Equationsmentioning

confidence: 99%

“…Decrease of shear-stress jump and widening of transition layer act as stabilizing factors. Irradiation of dislocation from a melting front above some threshold for uniaxial stress p xx has been observed in [15].…”

Section: Model and Equationsmentioning

confidence: 99%

Two-temperature hydrodynamics of laser-generated ultrashort shock waves in elasto-plastic solids

Ilnitsky

Хохлов

Inogamov

et al. 2014

J. Phys.: Conf. Ser.

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View the article online for updates and enhancements. Abstract. Shock-wave generation by ultrashort laser pulses opens new doors for study of hidden processes in materials happened at an atomic-scale spatiotemporal scales. The poorly explored mechanism of shock generation is started from a short-living two-temperature (2T) state of solid in a thin surface layer where laser energy is deposited. Such 2T state represents a highly non-equilibrium warm dense matter having cold ions and hot electrons with temperatures of 1-2 orders of magnitude higher than the melting point. Here for the first time we present results obtained by our new hybrid hydrodynamics code combining detailed description of 2T states with a model of elasticity together with a wide-range equation of state of solid. New hydro-code has higher accuracy in the 2T stage than molecular dynamics method, because it includes electron related phenomena including thermal conduction, electron-ion collisions and energy transfer, and electron pressure. From the other hand the new code significantly improves our previous version of 2T hydrodynamics model, because now it is capable of reproducing the elastic compression waves, which may have an imprint of supersonic melting like as in MD simulations. With help of the new code we have solved a difficult problem of thermal and dynamic coupling of a molten layer with an uniaxially compressed elastic solid. This approach allows us to describe the recent femtosecond laser experiments. IntroductionShock compression of solids was being studied intensively last several decades [1]. Hugoniot Elastic Limit (HEL) is a key concept in this branch of science. Above the HEL uniaxially deformed state becomes impossible -instead, isotropization of stresses and deformations takes place. For such metals as aluminum, nickel, and so on, the usual values of HEL are small -this means that an elastic shock wave (SW) driven by piston at a stress near HEL has velocity D el only 1 − 2% higher than elastic sound speed c el . Until recently, before works [2-6], the elastic branch of Hugoniot was widely accepted as a linear function for stresses below the common HEL. This is why a strong elastic SW firstly observed in the excellent pump-probe experiments with femtosecond lasers done by Evans et al. [7] and Gahagan et al. [8] was not recognized as an elastic wave. Such an elastic SW moves with velocity notably higher the longitudinal sound speed, and notably faster than the plastic SW with the same amplitude of pressure. Estimating those papers we can say today that they were well ahead of their time. Recent calculations [9] show that in the experiments [7] degree of nonlinearity of elastic SW was significant D el /c el −1 ≈ 0.1−0.2. In

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“…Recent experimental and theoretical studies of micrometer-sized metal films under ultra-short picosecond shear and tensile stresses demonstrated that materials can exhibit the very high shear and spall strengths closely approaching the corresponding theoretical ultimate mechanical properties [1][2][3][4][5][6]. Non-mechanical response of shocked materials, including non-equilibrium polymorphic phase transitions and melting, has also attracted the particular attention [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

The behavior of iron under ultrafast shock loading driven by a femtosecond laser

Ашитков

Zhakhovsky²,

Inogamov

et al. 2017

AIP Conference Proceedings

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Abstract. The results of experimental and theoretical investigations of shock-wave propagation in bcc iron under ultra-short loads driven by femtosecond laser pulses are presented. Chirped pulse interferometry was used for continuous diagnostics of movement in a picosecond range of the rear-side surface of thin iron films. The evolution of ultra-short elastic-plastic shock waves in samples with different thicknesses and purity has been studied. The obtained HEL and spall strength are close to ultimate values of shear and tensile stresses. Response of single-crystal iron to ultra-short shock loading/unloading was also explored in micron-sized films by molecular dynamics simulations. The experimental and simulation results on shock-induced elastic-plastic transformation and phase transition from bcc to hcp iron in a picosecond range of loading are discussed.

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Ultrashort shock waves in nickel induced by femtosecond laser pulses

Cited by 86 publications

References 33 publications

Attenuation of the Dynamic Yield Point of Shocked Aluminum Using Elastodynamic Simulations of Dislocation Dynamics

Attenuation of the Dynamic Yield Point of Shocked Aluminum Using Elastodynamic Simulations of Dislocation Dynamics

Two-temperature hydrodynamics of laser-generated ultrashort shock waves in elasto-plastic solids

The behavior of iron under ultrafast shock loading driven by a femtosecond laser

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