Advanced design of periodical architectures in bulk metals by means of Laser Interference Metallurgy

Patterning of high-resolution features on large-area metallic substrates has been performed by means of the Laser Interference Metallurgy method. Due to the intensity distribution of the interference pattern, this technique allows to locally and periodically heat the material surface to temperatures higher than the melting point with a long-range order. In this study, commercial stainless steel, copper and aluminum substrates were irradiated using single pulses of a nanosecond Nd:YAG laser with two and three laser-beam configurations operating at 355 nm of wavelength. Thermal simulations have been performed by finite element method and compared to the experiments. The results indicate that the structuring is produced by a surface tension driven mechanism induced by the thermal gradient. Moreover, metals with short thermal diffusion lengths present very homogeneous structures and the structure depth that can be achieved at relatively high laser fluences during single-pulse experiments is on the order of the diffusion length.