Modeling Microstructural and Mechanical Properties of Solidified Al-Sn-Cu System

Abstract

In this study,three samples were created using gravity die casting, i.e.,two modelsof immiscible alloys, Alloy1 (Al-12wt.%Sn-8wt.%Cu) and Alloy2 (Al-20wt.%Sn-10wt.%Cu),along with a control sample of pure Al.These gravity die-cast samples,homogenized at 700°Cfor 2hours,are analyzed formechanical properties and microstructures.Optical microscopy and scanning electron microscopy with energy dispersive spectroscopy (EDS) were used to analyze the changes in the Al-Sn-Cu solidified system resulting from the addition of specific alloying elements. Both Alloy1 and Alloy2 showed better mechanical properties than the control sample of pure Al. The tensile strength of Alloy2 shows a decrease from 110.878 MPato 105.750 MPacompared to Alloy1. However, there isan increase in the yield strength from 30.239 MPa to 32.362 MPa when the addition of tin exceeds 12% and copper exceeds 8%, respectively, which might be because of the alpha-phase solid solution’s interdendritic region that produces lattice strains.The impact resistance and ductility of the alloy are compromised as the hardness increases with the addition of more alloying elements. Alloy2 exhibited the highest hardness at 50.92 HB. The Brinell hardness values suggest these alloys arepotential candidatesto replace antifriction bronzes. However, hard CuAl2 is produced at the grain boundaries when copper percentages are increased, reducingthe impact properties. The effects of different alloying constituents and melt treatment on the microstructural control of Al-Sn-Cu solidified alloy werealso studied. The aluminum matrix with a semi-continuous network (reticular) distribution of tin on the grain boundary was observed. The grain size gradually decreased from 19.65 μm to 16.94 μm and became more equiaxed for Al-20wt.%Sn-10wt.%Cu than Al-12wt.%Sn-8wt.%Cu. The bond between tin and matrix improved with the increasing alloying element. The data obtained from this experiment will undoubtedly contribute to future research in this field