Effects of Silver Content and Cooling Rate on Electrical Conductivity and Tensile Properties of Al-Si(-Ag) Alloys

In recent years, new designing of components provided by electronics and automotive industries has required higher mechanical properties and electrical conductivity. Some of the examples are mobile phone frames, automotive powertrain components and new aluminum (Al) housing components. Silver (Ag) and Al have similarities in terms of crystal lattices and atoms diameters. Consequently, the addition of Ag in Al alloys may result in improved properties. The present research focuses on better understanding of the effects of Ag additions and cooling rate variations on the length scale of the dendritic microstructure constituting a Al-5 wt.% Si alloy. One of the factors to be considered during examination of as-cast Al-Si(-Ag) alloys microstructures is the interdendritic spacing. This factor, in combination with the second phases and solid solution, is able to control the application properties. In the present investigation, the ultimate tensile strength increases from 142 MPa for the Al-5 wt.% Si-0.1 wt.% Ag alloy to 154 MPa for the Al-5 wt.% Si-2.0 wt.% Ag alloy. This difference is not observed for ductility, which is preserved essentially unchanged into an improved value of 22% for both Ag-containing alloys. The less Ag-modified alloy samples (0.1 Ag) enhanced electrical conductivity by about 2% and 4% IACS as compared to those of the Al-5 wt.% Si and the Al-5 wt.% Si-2.0 wt.% Ag alloys samples, respectively.