On the Effect of Cooling Conditions and Variation of Alloying Elements on the Microstructural and Mechanical Properties of Al-7Si Cast Alloys

摘要

In order to study the isolated influence of microstructure and alloying elemets on the mechanical properties of Al-7%Si based alloys, the level of defects arising from the melt handling and cast process needs to be minimized. Therefore, gradient solidification technology has been applied, providing tensile test samples with a low content of defects and a well-fed homogenous microstructure. In the present work, the influence of cooling rate and Mg, Cu, Fe and Mn on the as-cast microstructure formations and mechanical properties such as ultimate tensile strength, yield strength, elongation to fracture etc. has been elucidated. While Cu and Mg strengthen the material, Fe deteriorates mostly the elongation. The length of Al_5FeSi-needles appears to be a function of the cooling rate and not of the content of iron in the melt.