Structural studies of binary and ternary Al alloys

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The present proposal would allow development of systematic research efforts, which focus on the structure-property relationship in Al alloys of industrial importance. The studies will be carried out on model binary and ternary systems, which will include pure Al, Al-1at%Mg, Al-3at%Mg, Al-1at%Mg-1at%Si and Al-0.2at%Cr.  The proposed program assumes comprehensive studies of mechanical and electrical properties and of various microstructural features developed during plastic flow over the range of temperatures between 4.2K and 300K. The project will allow elucidating the contribution of alloying elements such as Mg, Si and Cr and other microstructural elements including dislocations and point defects on the formability of Aluminium alloys. The experiments will be conducted on well-characterized polycrystals of these materials. Unique deformation facilities available in applicants' laboratory, together with SEM-OIM techniques, TEM techniques such as weak-beam TEM and HREM, and electrical resistivity measurements will be employed to study processes, which lead to fracture in the region of high strains. The study will also address the questions pertaining to the nature of defects acumulated in the matrial, the maximum density of these defects stored in the lattice, and the intrinsic instability of deformation structures at the onset of fracture. These questions are of basic significance for the understanding of the relationship between alloy composition deformation substructure and the limits of plasticity in the cold worked Al-alloys. This knowledge can be used for the development of new alloys, which will exhibit better combination of functional properties to be utilized in automotive applications. The experiments will be linked with theoretical efforts to model deformation behaviour in these materials based on available approaches. The detailed knowledge of alloy behaviour will improve the reliability in processing operations and therefore will increase productivity in this industry sector.