Microstructure, Phase Formation and Heat-Treating of Novel Cast Al-Mg-Zn-Cu-Si Lightweight Complex Concentrated Aluminum Based Alloy

Abstract

In the current work, a novel complex concentrated aluminum alloy is designed and studied. In order to investigate the unknown region of the multicomponent phase diagrams, thermo-physical parameters and the CALPHAD method were used to understand the phase formation of the Al58Mg18Zn12Cu5Si7 at.% (Al47.4Mg13.3Zn23.8Cu9.6Si6wt.%) alloy with a low-density of 2.63 g/cm3. The CALPHAD methodology showed good agreement with both the investigated microstructure and the thermodynamic parameters. The designed alloy was manufactured using an induction furnace and pour mold casting process. This study avoids the use of expensive, dangerous or scarce alloying elements and focuses instead on the utilization of widely available relatively cheaper elements. The microstructural evolution as a function of the heat-treatment was studied by means of different microstructural characterization techniques. The hardness, compressive strength and electrical conductivity of the as-cast and heat-treated alloy at room temperature were studied and correlated with the previously characterized microstructure. The alloy is characterized by a multiphase microstructure with major α-Al matrix reinforced with various secondary phases. In terms of mechanical properties, the developed alloy exhibited a high hardness value of 249 Vickers and compressive strength of 588 MPa. The present work provides a valuable insight for researchers, who aim to design and produce industry-like Aluminum based complex concentrated alloys (CCAs).