Development of high-strength and corrosion resistant aluminum alloys

Aluminum alloys are of outstanding importance to industries requiring lightweight materials. The remarkable properties of Al alloys, which come in a variety of grades, are unsurpassed for many applications. However, these properties are limited by conventional techniques, and given the potential of aluminum alloys, novel techniques and materials are critical to achieving alloys with superior properties. The interplay between strength and corrosion is a rarity in Al alloys, as the corrosion resistance of Al alloys has deteriorated following efforts to strengthen them. The present study aims to simultaneously enhance the strength and corrosion performance of Al alloys through nanocrystalline structure, enhanced solubility of alloying elements and uniform distribution of secondary phases by high energy ball milling. The present work involves the synthesis and characterization of ultra-high strength, highly corrosion resistant light Al alloys by high energy ball milling and suitable alloying elements. The methodology includes a top-down approach starting with high-energy ball milling of commercial age-hardening alloys and modifying process parameters to achieve higher alloy performance. Finally, based on the knowledge gained from commercial alloys, the synthesis of binary alloys and the mechanisms that provide excellent properties were investigated. Many viable alloying elements were investigated to fill the research gap on binary Al alloys, although the role of each alloying element may vary and therefore each alloy system should be treated as an individual case. Therefore, the corrosion protection mechanism of the Al-Fe system has been studied in detail through electrochemical along with analytical techniques such as XPS, TEM, SIMS. Understanding how Fe significantly improves the corrosion resistance of Al in solid solution and nanocrystalline structure can guide the development of a new generation of light metal alloys for applications with the most desired mechanical properties and aggressive environments.