Direct micro-patterning of aluminum substrates via laser interference metallurgy

Laser interference metallurgy (LIMET) holds the challenge to create advanced structures with a well-defined long-range order in the submicrometer scale. In LIMET a spatial variation of laser intensity is created by means of the interference of two or more laser beams. The pattern generated by the intensity distribution is transferred to the material to produce periodic structures. In this work, the mechanisms of structure formation on aluminum surfaces are studied. For this purpose a nanosecond Nd:YAG laser is used. The effects of laser energy density and grating distance on the formation of micro-structures are investigated. Thermal simulations are also performed in order to analyze the experimental results. We propose the combined action of surface-tension-driven flow and recoil pressure induced by material evaporation as the main forces to create the periodic structures.