Cast aluminium-silicon alloys have been found attractive over ferrous alloys for applications in automotive pistons. As a result, production of piston components from cast aluminium-silicon alloys has increased, which, in turn, has led to increase in volume of scrap of these alloys. Consequently, there is concerted effort in research to develop effective procedures of recycling. As part of this effort, this book provides an investigation of the microstructure and microhardness evolution of recycled cast aluminium-silicon piston alloys processed by high-pressure torsion (HPT). It is an attempt to evaluate HPT for recycling of Al-Si piston alloys. The results presented here are very useful to readers in both academia and industry, especially those interested in severe plastic deformation, metal forming, material processes and aluminium recycling. The book is very useful to both undergraduate and postgraduate students. This book is a must for those interested in design of novel mechanical metal processing techniques in industries and laboratories.