Fabrication of Hard Alloys Patterns with Fractal Structures on Light Metal Substrates through Reaction Diffusion

Abstract

  Fractal patterns composed of hard alloys were created on light metal substrates for surface stress control by using a laser scanning stereolithography and reaction diffusion treatments. Photo sensitive urethane resin including pure copper particles of 75 μm in average diameter was spread on tensile specimens of pure aluminum with 100 μm in layer thickness. Hilbert fractal curves with self-similarities of 1, 2 and 3 in stage number were drawn by single stroke scanning of an ultra violet laser beam of 100 μm in spot size. Self similar patterns composed of copper aluminides were created through heat treatments at 600°C above eutectic temperature for 8 hs in an argon atmosphere. Microstructures and composite distributions were observed by a scanning electron microscopy and energy dispersive X-ray spectroscopy, Measured mechanical properties by tensile tests were compared with simulated ones by finite element method. Above mentioned fractal patterning of hard alloys can be expected to strengthen the light metals efficiently through controlling of surface stress distributions.