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Influence of Processing Parameters on Morphology and Structure of Single Spot Excimer Laser Melted Mg Alloy Surfaces
Bhaskar Majumdar, Rolf Galun, Barry L. Mordike and Andreas Weisheit

The present investigation deals with the surface melting of Mg alloy using an excimer laser. All experiments were carried out to expose the material by laser on a single spot condition. We have aimed at understanding the effect of processing parameters on the melting behaviour of AZ91 alloy surface. The surface roughness, melt depth and structure have been correlated with the processing parameters. The topological features i.e, structure of surface and surface roughness are found to be dependent on the intensity of the laser power. There exists a linear relation between melt depth and laser energy density, the slope of the line obtained from experimentally measured value coincides with the theoretically calculated one but discrepancy exists in the absolute value of melt depth. The transmission electron microscopic investigation reveals the presence of nanocrystalline oxides and nitrides in submicron sized grains of Mg solid solution. The submicron grain size is independent of processing parameters.

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