Effects of Silver Content and Cooling Rate on Electrical Conductivity and Tensile Properties of Al-Si(-Ag) Alloys
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JMEPEG https://doi.org/10.1007/s11665-020-05141-w
Effects of Silver Content and Cooling Rate on Electrical Conductivity and Tensile Properties of Al-Si(-Ag) Alloys Leonardo Fernandes Gomes, Paulo Se´rgio da Silva Jr., Amauri Garcia, and Jose´ Eduardo Spinelli (Submitted July 1, 2020; in revised form August 14, 2020) 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 Al5 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. Keywords
Al-Si-Ag alloys, electrical microstructure, tensile properties
conductivity,
1. Introduction Attempts have been made to design high-strength and highductility Al alloys by governing their microstructure features, as a result of the implementation of more rigorous requirements regarding improvements in fuel economy and reduction in gas emissions. There is a growing movement to replace steel and cast iron in vehicles with lightweight metals, such as Al casting alloys. Nonetheless, due to the presence of improper microstructures and casting defects, these alloys do not always possess appropriate mechanical properties (Ref 1). Therefore, an important question in understanding the different properties of these materials is the study of solidification behavior of multicomponent alloys systems. Many commercial materials properties are determined by the microstructure that evolves during solidification and in consecutive processing stages. The comprehension of how multiphase microstructures form and how they can be controlled Leonardo Fernandes Gomes, Graduate Program in Materials Science and Engineering, Federal University of Sa˜o Carlos, Sa˜o Carlos, SP 13565-905, Brazil; Paulo Se´rgiodaSilva Jr., Department of Physics, Federal University of Sa˜o Carlos - UFSCar, Sa˜o Carlos, SP 13565-905, Brazil; A
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