Effect of Ternary Scandium and Quaternary Zirconium and Titanium Additions on the Tensile and Precipitation Properties of Binary Cast Al-6Mg Alloys

Effect of ageing on the mechanical properties of Al-6Mg alloy doped with 0.4 wt% scandium and with or without trace zirconium and titanium is studied. As cast, samples were aged isochronally for 60 minutes at different temperatures up to 500°C. The evaluation of tensile properties of the aged Al-6Mg (Sc, Zr, Ti) alloys was conducted by employing an Instron testing machine. Various strain rate of the tensile testing were used to find out the values of strain rate sensitivity of the experimental alloys. The influence of scandium is more pronounced on yield strength than on the tensile strength. Alloys with scandium, zirconium and titanium content have shown higher yield strength and the values of ‘m’ at peak-aged condition has been found to be comparatively high at quaternary addition. The fracture of the experimental alloys occurs through micro void coalescence. The transmission electron micrograph is seen to contain second phase constituent at the grain boundaries.