This Reprint presents a collection of pioneering research and critical reviews on the design, development, and processing of aluminum alloys and their composite materials. Addressing the modern industrial demand for materials with superior specific strength, toughness, and functionality, the contributions in this volume explore the entire value chain-from compositional design and solidification control to advanced processing and characterization. Key themes include the management of iron-rich impurities in recycled alloys, the micro-alloying with rare earth elements (yttrium, samarium) to modify microstructures and enhance properties, and the application of novel processing routes such as twin-roll casting and friction stir spot welding. Furthermore, advanced characterization techniques and first-principles calculations are employed to understand interface characteristics and failure mechanisms. Collectively, this Reprint provides a comprehensive overview of current strategies to overcome limitations in traditional aluminum processing, paving the way for high-performance, sustainable, and industrially viable aluminum-based materials for applications ranging from aerospace to electronics packaging.