Excimer laser crystallization of quasicrystalline coatings on engineering substrates
Quasicrystals (QC) are materials with a unique combination of material properties including low friction, non-wetting behavior, high hardness and low thermal conductivity. However, very limited ductility and high temperature annealing requirements have limited its application. In this work, the laser crystallization of the amorphous quasicrystalline thin films deposited by magnetron sputtering on aluminum, steel, and titanium substrates was investigated using a 248-nm excimer laser. The effect of laser glazing on the crystallographic properties and the mechanical properties of the crystallized layers were studied along with laser annealing as a function of the laser fluence, pulse repetition rate and scan rate. The thermal phenomena associated with laser crystallization were identified using a 2-D ANSYS finite element model of numerically solving the governing heat flow equation. Further, X-ray diffraction, solidifications structure and ripple formation provided the evidence that the phase change from amorphous to crystalline involved the formation of liquid phase which also caused surface roughening.