Effects of Sc(Zr) on the microstructure and mechanical properties of as-cast Al-Mg alloys

摘要

Both the addition of 0.6% Sc and simultaneous addition of 0.2% Sc and 0.1% Zr exerted a remarkable effect on grain refinement of as-cast Al-Mg alloys, changing typical dendritic microstructure into fine equiaxed grains. Such effect was found to be related to the formation of primary particles, which acted as heterogeneous nucleation sites for alpha-Al matrix during solidification. Primary particles formed in Al-Mg-Sc-Zr alloy could be identified as the eutectic structure consisting of multilayer of 'Al-3(Sc, Zr) + alpha-Al + Al-3(Sc, Zr)', with a 'cellular-dendritic' mode of growth. In addition, an attractive comprehensive property of as-cast Al-5Mg alloy due to the addition of 0.2% Sc and 0.1% Zr was obtained.