| Abstract: | In the present research, the Al-Si alloy surface is treated by KrF excimer pulse laser for different number of laser pulses in ambient condition at energy 4.75 J/cm2. The surface microstructural characterization was done by the optical microscope, in situ video recording during laser pulsing, SEM and TEM. The fretting wear test was undertaken to assess the tribological behavior. In situ video recording showed changes in the surface reflectivity with the number of pulses which is related to progressive changes in the surface compositional homogeneity. After ten pulses, signs of rippled structure were observed. The 15 pulse samples showed star-like morphological feature at the central region. The TEM observations showed high density of stacking faults/twins in Si after first pulse treatment. After 15 pulses, nano-crystalline Si precipitates in the size range <5 nm are seen to be homogeneously distributed. A cellular structure with the cell size <100 nm formed in the matrix. These cell boundaries were decorated with the Si nanocrystals. A positive effect in wear resistance property is observed after the 15 pulses treatment. |
