Aluminium alloys with a wide range of properties are used in engineering structures. These properties can be largely modified by changing the alloy composition and by cold working. Si, Cu, Zn and Mg are the most commonly used alloying elements in aluminium, which have sufficient solid solubility. The as-cast microstructure of cast aluminium alloys normally displays significant segregation and supersaturation. For this, homogenization of aluminium alloys is often done to improve workability and mechanical properties. This book is based on the research about influence of Cu content, cold working and homogenization in Al-Si alloys. The effects were analysed using microstructure study, phase-property modelling, image analysis and hardness measurement. This work should help researchers and metallurgists who are working on modification of alloy properties. Also it will help students who have keen interest in study of microstructure, modelling and image analysis.