Excimer laser treatment of magnesium alloy surface

XeCl excimer laser radiation is employed to produce a melted surface layer on the Mg alloy (AZ91). This layer can render the alloy both corrosion and wear resistant by the way of microstructural refinement. Individual spots as well as overlapping regions are produced using various processing conditions. Both the surface morphologies and the microstructures of the laser melted zones are characterised and correlated with the processing parameters. Meanwhile, authors have developed a technique resulting in melted layer thickness of 50 to 100 μm. The microhardness values of these layers increase to a maximum which is otherwise achievable only through the addition of alloying elements. Detailed transmission electron microscopy reveals the presence of MgO nanoparticles embedded in nanocrystalline grains within the Mg alloy surface layers; the very high microhardness values are attributed to these extreme structural refinement.