Laser Interference metallurgy -: using interference as a tool for micro/nano structuring

Interfering laser beams of a high-power pulsed laser provide the opportunity of applying a direct lateral interaction with the surface microstructure of metals in micro/nanoscale based on photo-thermal nature mechanisms. This "Laser interference metallurgy" allows the creation of periodic patterns of features with a well defined long-range order on metallic surfaces at the scale of typical microstructures (from the sub micrometer level up to micrometers). This technique is an approach to initiate metallurgical processes such as melting, recrystallization, recovery, and defect and phase formation in the lateral scale of the microstructure itself and with an additional long range order given by the interference periodicity. In this work, the laser interference theory is described and used to calculate multi-beam interference patterns. A method to calculate the numbers of laser beams as well as the geometrical arrangement of the beams to obtain a desired periodical pattern prior to experiments is presented. The formation of long-range-ordered intermetallic compounds as well as macroscopic and microscopic variations of mechanical properties on structured metallic thin films are presented as examples.