Mechanical behavior due to innovative processes on light alloys: a review

Due to the continuous development of new technologic processes and surface treatments, new applications of high strength-to-mass ratio light alloys in the advanced aerospace, automotive and naval fields are becoming key factors in the mechanical design of innovative structural components. The recent advancements in the field of the Friction Stir Welding (FSW) technique, leading to improved weldability of high performance light alloys, are opening new horizons in the design of advanced machine parts. The surface characteristics of such alloys, which are traditionally an obstacle in the realization of components subjected to high contact forces, are nowadays improved by the adoption of low-temperature, hard and thin coating processes, such as the Physical Vapor Deposition (PVD) technique. A wide selection of coatings is applicable on different substrates, providing the material with an hard, low friction and wear resistant surface, often accompanied by a desirable compressive stresses pattern. However, due to the advanced nature of such processes, the actual effects of these treatments on the substrate are not always univocally defined in terms of mechanical properties. In the last decade, several studies have been produced on this subject, often analyzing a single effect on a single base material. The present work collects a review of the most recent analyses on the mechanical effects generated by innovative welding techniques such as FSW, as well as deposition PVD processes on light alloys for advanced application, thus giving to the mechanical designer a widespread view over possible new applications of these materials.