P. S. Komarov

Behavior of aluminum near an ultimate theoretical strength in experiments with femtosecond laser pulses

The dynamics of the motion of the free surface of micron and submicron films under the action of a compression pulse excited in the process of femtosecond laser heating of the surface layer of a target has been investigated by femtosecond interferometric microscopy. The relation between the velocity of the shock wave and the particle velocity behind its front indicates the shock compression to 9–13 GPa is elastic in this duration range. This is also confirmed by the small (≤1 ps) time of an increase in the parameters in the shock wave. Shear stresses reached in this process are close to their estimated ultimate values for aluminum. The spall strength determined at a strain rate of 109 s−1 and a spall thickness of 250–300 nm is larger than half the ultimate strength of aluminum.

Achievement of ultimate values of the bulk and shear strengths of iron irradiated by femtosecond laser pulses

Shock-wave phenomena generated by femtosecond laser pulses in submicron iron film samples have been studied by the interferometric method with the application of frequency-modulated diagnostics in the picosecond time range. The splitting of the shock wave into the elastic and plastic waves with a compression stress of up to 27.5 GPa behind the front of an elastic precursor has been detected. The corresponding maximum shear stress reaches 7.9 GPa, which is even somewhat higher than the calculated ideal shear strength. The measured spall strengths reach 20.3 GPa, which is also comparable to the calculated values of the ideal tensile strength.

Strength properties of an aluminum melt at extremely high tension rates under the action of femtosecond laser pulses

AbstractThe dynamics of the melting of a surface nanolayer and the formation of thermal and shock waves in metals irradiated by femtosecond laser pulses has been investigated both experimentally and theoretically. A new experimental-computational method has been implemented to determine the parameters of laser-induced shock waves in metallic films. Data on the strength properties of the condensed phase in aluminum films at an extremely high strain rate (

Deformation resistance and fracture of iron over a wide strain rate range

\dot V

Strength of metals in liquid and solid states at extremely high tension produced by femtosecond laser heating

/V ∼ 109 s−1)under the action of a laser-induced shock wave have been obtained.

Ultrafast lasers and solids in highly excited states: results of hydrodynamics and molecular dynamics simulations

The evolution of compression pulses generated by a femtosecond laser in micron-thick vanadium film samples has been studied by the interferometric method with continuous recording of motion in the picosecond range. The relation of the velocity of a shock wave and the particle velocity behind its front indicates the elastic character of shock compression at pressures up to 46 GPa, for which the shear stress is 15.8 GPa. The measured spall strength reaches 21.8 GPa at a strain rate of ∼109 s−1. The picosecond dynamics of the reflection coefficient of vanadium, which indicates the excitation of its electronic subsystem under “cold” compression by an ultrashort shock wave, has been detected.

The effect of an ultrashort laser pulse on metals: Two-temperature relaxation, foaming of the melt, and freezing of the disintegrating nanofoam

The results of measurements of the decay of an elastic precursor in iron at the distances from 0.13 to 10 mm and the spall strength of the samples with such thicknesses have been compared with similar data for the nanometer-scale samples. The decay has been described by a unique dependence whose differentiation gives the relationship between the initial plastic strain rate in the range from 103 to 109 s−1 and the compression stress in the elastic shock wave from 1.5 to 27.5 GPa. The dynamic breaking strength (spall strength) varies in this range of shock-wave load time from 1.5 to 20 GPa.

Experimental and theoretical study of Al plasma under femtosecond laser pulses

The destruction of liquid tin at the extremely high strain rate caused by femtosecond laser pulses has been studied. The ablation and cavitation thresholds, as well as tensile stresses responsible for the destruction of liquid tin at a strain rate of ∼109 s–1, have been experimentally determined.