Eutectic Al-Si-Cu-Fe-Mn alloys with enhanced mechanical properties at room and elevated temperature

In this paper, we report a novel kind of eutectic Al-Si-Cu-Fe-Mn alloy with ultimate tensile strength up to 336 MPa and 144.3 MPa at room temperature and 300 degrees C, respectively. This kind of alloy was prepared by metal mold casting followed by T6 treatment. The microstructure is composed of eutectic and primary Si, alpha-Fe, Al2Cu and alpha-Al phases. Iron-rich phases, which were identified as BCC type of alpha-Fe (Al-15(Fe,Mn)(3)Si-2), exist in blocky and dendrite forms. Tiny blocky Al2Cu crystals disperse in alpha-Fe dendrites or at the grain boundaries of a-Al. During T6 treatment, Cu atoms aggregate from the super-saturation solid solution to form GP zones, theta '' or theta'. Further analysis found that the enhanced mechanical properties of the experimental alloy are mainly attributed to the formation of a-Fe and copper-rich phases. (C) 2011 Elsevier Ltd. All rights reserved.