Effect of Changing Filler Rod on Microstructure and Corrosion Behavior of Al/Mg2si Surface Composite Fabricated By Tig Welding

Al / mg2si surface composite was fabricated by tungsten inert gas (tig) welding at a current intensity of 150 a using three types of filler rods including 1100, 4047 and a combination of 4047 and 5356 filler rods. the phases created were identified by the x-ray diffraction (xrd) method and the microstructures of the 3 samples were investigated by optical and scanning electron microscopes. their corrosion behavior was also tested by a potentiostat instrument. the corresponding results showed that changing the filler rods used led to changes in the morphology of the resultant coatings. in addition, although sample 3 (coated with a combination of 4047 and 5356 filler rods with the maximum amounts of si, mg, fe, and cu) had the greatest gas porosities in the weld zone, it exhibited a good distribution of dissolved magnesium and silicon precipitates. the weld zone of this sample included the α-al matrix, al-si eutectic and mg2si precipitates. in this case, the corrosion resistance of the coatings also increased.