Formation of surface periodic microstructure at laser irradiation of the multilayer Ni/Cu/Cr system

The effect of periodic pulsed laser irradiation (λ = 1.06 μm and power density of 0.6-0.8 × 104 W/cm2) on the solid-phase reaction in thin-film Ni/Cu/Cr structure (each layer of 100 nm thick) is studied by means of Auger electron spectroscopy and scanning electron microscopy. Thin-film structure is found to transform under irradiation into eutectic Cr-Ni structure with the particles of the leading Cr(Ni) phase having the radii equal to the total thickness of the film (300 nm). Eutectic colonies of these particles form the surface microstructure which consists of periodic arc-shaped bands with bars between them. The laser-induced diffusion is shown to occur under the sign-variable temperature gradient (∼105 K/s), high deformation rate (∼20 s−1), and large dislocation flow (ρv∼1011cm−1s−1) at low deformation degree (∼0.01).