This book deals with the importance of Al alloys and its composites in aerospace and automotive applications. A comparative study has been made to study the effect of various quenching media like water, salt brine, and oil on the hardening, and aging of Al metal matrix composites (MMCs). In modern aerospace applications, the selection of a quenching agent is critical for higher strength and reliability of Al components. In particular, this book presents the investigation and study of the age hardening behavior of Al-4.5%Cu alloy reinforced with zircon sand particles, synthesized by stir casting in various quenching agents. Limited work has been done when the hardening behavior of Al-Cu alloy composites are characterized in different quenching media other than water. The effects of various quenching agents on age hardening have been examined along with thermal cycling of composites. This book will be useful at undergraduate, postgraduate or doctorate level courses in mechanical, materials, aerospace, metallurgy and other interdisciplinary areas.