Effect of Al-15Zr Master Alloy and Extrusion Process on Microstructure and Mechanical Properties of Al-6%Mg Alloy

In current research different amounts of Al-15Zr master alloy were added to Al-6%Mg alloy to obtain various Zr concentrations (0.01, 0.03, 0.05, 0.1, 0.2, 0.3% weight percent). The microstructural study was carried out on Al-6%Mg extruded alloy. It was found that with the increase of Al-15Zr master alloy, Al (α) matrix morphology was changed from dendritic to equiaxed grains due to the suppression of grain growth by the formation of homogeneous Zr containing disperoids at grain boundary. The grain size of as-cast alloys was significantly decreased by adding Al-15Zr master alloy to same extent. An increase in the amount of Zr content resulted in improvement of ultimate tensile strength (UTS) and elongation (%El) values. Fractographic examinations of the alloy showed a ductile mode of fracture via introducing more homogenous fine dimples after grain refining process.