Tailoring the chemical behavior of aluminum for selective etching by laser interference metallurgy

The chemical behavior of aluminum modified by laser interference metallurgy (LIMET) is investigated. LIMET allows the single-step creation of periodic patterns with a well defined long-range order on material surfaces. This technique can also induce local and periodical oxidation on aluminum surfaces, which follows the ordered array imprinted by laser interference. The thin oxide layer built up during laser structuring enhances the chemical stability of the irradiated zones. Ordered local oxidation permits the selective etching of an exposed aluminum surface. The etch pits are generated preferentially at the interference minima positions. In comparison to conventional methods, this process significantly improves the homogeneity of the initiation sites of pits. Furthermore, LIMET not only influences the first stages of pits initiation, but also the final etch morphology formed during the total electrochemical etching of the surfaces.