Effect of cryogenic and heat treatment on microstructure and mechanical properties of Al-7Si-1,5Cu-Mg

An Al-7Si-1.5Cu-Mg alloy was synthesized through the modification of a commercial A356 alloy with the inclusion of alloying elements. This alloy underwent a treatment regime comprising solid solution, cryogenic treatment, and ageing. The results indicate that cryogenic treatment increased nucleation rate of precipitates, which increases the number of precipitates and reduces their sizes, ultimately improving the mechanical properties and reduce secondary dendrite arm spacing of the alloy. Under the optimal treatment conditions (solid solution at 520 °C for 10 hours, followed by deep cooling for 48 hours, and ageing at 160 °C for 10 hours), the secondary dendrite arm spacing of the alloy was reduced by approximately 37,5 %, exhibiting hardness of 102,8 HV and plasticity of 4,2 %