Future Work and Possible Applications of Nanocrystalline Al Alloys as Produced by High-Energy Ball Milling

High-energy ball milled Al alloys have demonstrated extraordinary properties due to grain refinement to the nanoscale, and increased solid solubility of alloying elements. For example, the compressive yield strength of 1200 and 1105 MPa was observed in Al-Fe [1] Al-Cr alloys [2], both prepared via HEBM followed by consolidation. The specific compressive yield strength of an Al-20Cr alloy was compared with that of the commercial alloys and high-energy ball milled alloy surpassed the specific yield strength of the commercial alloys indicating a possibility of a development of a new class of light metals with high strength (Fig. 7.1). Moreover, corrosion performance of the nanocrystalline alloys was shown to improve significantly. For example, Gupta et al. [2, 3] reported a significant improvement in corrosion performance of both nanocrystalline alloys. In contrary to commercial alloys, where corrosion performance diminished with strength, high-energy ball milled alloys exhibited simultaneous improvement in corrosion resistance and strength due to the extended solid solubility of suitable solute and grain refinement to nanoscale. In summary, the high-energy ball milled Al alloys exhibited revolutionary properties and showed promise to develop future lightweight materials exhibiting ultra-high strength and improved durability. In spite of the attractive properties, the research on these alloys is in an early stage and further research is required to gain fundamental insight and ensure the engineering applications.