Effect of Alloy Composition on Microstructure and Tensile Properties of Net-Shaped Castings of Al–Zn–Mg–Cu Alloys

In this study, the effect of alloy composition on uniaxial tensile properties of Al–Zn–Mg–Cu alloys was investigated using seven distinctive alloy compositions. The sample alloys were manufactured as net-shaped components using the controlled diffusion solidification technology coupled with the tilt pour gravity casting process. The effect of T4 and T6 heat treatment on the castings was investigated using seven alloy compositions with the total alloying content (Zn + Mg + Cu) varying from 4.6 to 10.6 wt%. The uniaxial tensile yield strengths (0.2% proof stress) of the respective alloys were measured for T4 temper and varied between 125 and 316 MPa and for the T6 temper samples varied between 280 and 540 MPa. A quantitative image analysis was carried out to measure the eutectic phase fraction, which was compared with predictions from thermodynamic solidification simulations. The experimental phase characterization of various secondary phases/precipitates was conducted using an electron microscopy (STEM) methodology along with energy dispersive spectroscopy (EDS) results; other experimental method such as the Archimedes’ density measurements was also used to evaluate porosity content in the samples.