Essential 5083, 6061, and 7075 aluminum alloys are prone to hot tearing, and their solidification and defect formation behaviors are sensitive to common alloying elements such as Fe, Si, Cu, and Ti. This research intends to use the "constrained rod casting (CRC) method with a steel mold" as the starting point and change the alloy composition under the 5083, 6061, and 7075 aluminum specifications. We aim to combine (i) the CRC method for quantifications of hot tearing susceptibility, (ii) the computational phase diagram (CALPHAD) for thermodynamic analysis, and (iii) multiscale microstructural characterizations and phase identification approaches. Those analysis approaches are useful for interpreting hot-tearing formation mechanisms and understanding multiphase interactions among intermetallic compounds, primary aluminum crystals, and remaining interstitial liquid as a function of compositional variations. After summarizing the research results, it will help to capture the influence of Fe, Si, Cu, and Ti on the resulting solidification microstructure and properties, to establish the control standards for the compositions of 5083, 6061, and 7075 series aluminum alloys, and to direct the process scale-up work for direct-chill (DC) casting with the usage of increasing proportions of recycled aluminum materials.