Effects of Be and Fe on the mechanical and corrosion behaviors of A357 alloys

This work investigated how Be and Fe affect the morphologies of iron intermetallics and silicon particles in addition to the mechanical and corrosion behaviors of A357 alloys. Experimental results show that many plate-like shape and Chinese-script shape iron-bearing phases were found in A357 alloys. These structures are replaced by a nodular shape Mg-free structure of iron-bearing constituents when Be is added. Adding Be to the alloy can increase the level of solid Mg solution, change the morphology of silicon particles to a small and globular shape, subsequently reducing the amount of iron-bearing phases. Be can also enhance the precipitation kinetics and increase the quantity of Mg2Si precipitates to improve the tensile properties of A357 alloys. The corrosion behavior of A357 alloy was affected by the morphology of the silicon particles and the amount of iron-bearing phases. The corrosion resistance improved when the amount of iron-bearing phases was reduced and the silicon particles were spheroidized and refined. Consequently, results reveal that both the addition of Be and the reduction of Fe improve the mechanical and corrosion resistance properties of A357 alloys.