Computer modeling of laser melting and spallation of metal targets

Leonid V. Zhigilei; Dmitriy S. Ivanov; Elodie Leveugle; Babak Sadigh; Eduardo M. Bringa

doi:10.1117/12.548821

20 September 2004 Computer modeling of laser melting and spallation of metal targets

Leonid V. Zhigilei, Dmitriy S. Ivanov, Elodie Leveugle, Babak Sadigh, Eduardo M. Bringa

Proceedings Volume 5448, High-Power Laser Ablation V; (2004) https://doi.org/10.1117/12.548821
Event: High-Power Laser Ablation, 2004, Taos, New Mexico, United States

Abstract

The mechanisms of melting and photomechanical damage/spallation occurring under extreme superheating/deformation rate conditions realized in short pulse laser processing are investigated in a computational study performed with a hybrid atomistic-continuum model. The model combines classical molecular dynamics method for simulation of non-equilibrium processes of lattice superheating and fast phase transformations with a continuum description of the laser excitation and subsequent relaxation of the conduction band electrons. The kinetics and microscopic mechanisms of melting are investigated in simulations of laser interaction with free-standing Ni films and bulk targets. A significant reduction of the overheating required for the initiation of homogeneous melting is observed and attributed to the relaxation of laser-induced stresses, which leads to the uniaxial expansion and associated anisotropic lattice distortions. The evolution of photomechanical damage is investigated in a large-scale simulation of laser spallation of a 100 nm Ni film. The evolution of photomechanical damage is observed to take place in two stages, the initial stage of void nucleation and growth, when both the number of voids and the range of void sizes are increasing, followed by the void coarsening, coalescence and percolation, when large voids grow at the expense of the decreasing population of small voids. In both regimes the size distributions of voids are found to be well described by the power law with an exponent gradually increasing with time. A good agreement of the results obtained for the evolution of photomechanical damage in a metal film with earlier results reported for laser spallation of molecular systems and shock-induced back spallation in metals suggests that the observed processes of void nucleation, growth and coalescence may reflect general characteristics of the dynamic fracture at high deformation rates.

Citation Download Citation

Leonid V. Zhigilei, Dmitriy S. Ivanov, Elodie Leveugle, Babak Sadigh, and Eduardo M. Bringa "Computer modeling of laser melting and spallation of metal targets", Proc. SPIE 5448, High-Power Laser Ablation V, (20 September 2004); https://doi.org/10.1117/12.548821

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