Enhancement of the mechanical properties in Al-Si-Cu-Fe-Mg alloys with various processing parameters

Abstract

In this research, various processing conditions were implemented to enhance the mechanical properties of Al-Si alloys. The silicon content was varied from hypoeutectic (Si-10 wt.%) to eutectic (Si-12.6 wt.%) and hypereutectic (Si-14 wt.%) for the preparation of Al-XSi-3Cu-0.5Fe-0.6Mg (X = 10-14%) alloys using die casting. Subsequently, these alloys were hot-extruded with an optimum extrusion ratio (17:1) at 400 °C tomatch the output extruded bar to the compressor size. An analysis of themicrostructural features alongwith a chemical compositional analysiswere carried out using scanning electronmicroscope along with energy dispersive X-ray spectroscopy and transmission electron microscope. The SEM micrographs of the extruded samples displayed cracks in primary Si, and the intermetallic (β-Al5FeSi) phase was fragmented accordingly. In addition, the silicon phase was homogenously distributed, and the size remained constant. Themechanical properties of the extruded sampleswere enhanced by the increase of silicon content, and consequently the ductility decreased. By implementing proper T6 heat treatment parameters, coherent Al2Cu phases were formed in the Al matrix, and the Si phase was gradually increased along with the silicon content. Therefore, high tensile strength was achieved, reaching values for the Al-XSi-3Cu-0.5Fe-0.6Mg (X = 10-14%) alloys of 366MPa, 388MPa, and 420MPa, respectively.