The Effect of Magnesium and Strontium Over-Alloying on the Mechanical Properties of AlSi9Cu3(Fe) Aluminum Alloy

The effect of magnesium and strontium over-alloying and heat treatment on the mechanical properties of a secondary aluminum alloy was investigated on both tensile strength and ductility. In this study, a gearshift holder was manufactured by vacuum-assisted cold chamber high-pressure die casting (VHPDC) by FémAlk Zrt. Using the same die, the part was produced from the secondary versions of the aluminum alloy AlSi9Cu3(Fe) (EN AC-46000) with increased magnesium and strontium concentrations. The cast parts were subjected to different heat treatments (T4, T1, T5, or T6), and they were investigated by microstructural and mechanical aspects. The aim was to replace a primary aluminum alloy and achieve a yield strength of 180 MPa and an elongation at break of 6%, by the over-alloying and proper heat treatment of the secondary alloy. The heat treatment could alter the morphology of silicon particles from small plate-like areas to globular shapes, resulting in more ductile behavior compared to the as-cast condition. The results show that the best combination was magnesium and strontium over-alloying in the T6 condition. This study is preliminary in this state, and further work is being conducted.