Computer modeling of laser melting and spallation of metal targets

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