Aluminum alloys are one of the widely used materials in the structural components of automobiles and especially aircraft. The valid prediction of the performance and life span of these components via running simulations requires the usage of sophisticated physics-based material models. Such models are based on the mechanical response and the underlying microstructure evolution at varied deformation conditions. With the above motivation in mind, the aim of the current doctoral thesis was to investigate and understand the relationship between processing, microstructure, mechanical and fracture behavior of AA7075-T651 alloy and recycled AlSi10MnMg(Fe) alloy.

First, the deformation behavior of AA7075-T651 alloy, which was initially drawn from extruded round bars, was studied through compression tests at low (0.01 and 1 s−1) as well as at high (1400 – 5300 s−1) strain rates and deformation temperatures ranging between room temperature (RT) and 500 °C. At low strain rate deformation, the alloy experienced more softening due to adiabatic heating arising from 1 s−1 strain rate up to 200 °C. Beyond 200 °C, the softening effect was taken over by dynamic recovery and dynamic recrystallization which were enhanced by 0.01 s−1 strain rate. The deformation at high strain rates and elevated temperatures led to the formation of adiabatic shear bands (ASBs) and cracks in the material. The feasibility of formation and growth of ASBs and cracks increased with increase in strain and temperature, neglecting any significant effect from the strain rate.

Secondly, the recycled secondary AlSi10MnMg(Fe) alloy, which was produced by high pressure die casting (HPDC), was investigated. The secondary alloy showed great potential of exhibiting the strength and ductility within the range exerted by its conventional primary counterpart, i.e., AlSi10MnMg alloy, however, its tensile properties were restricted by the inhomogeneously formed fine-grained skin layer on the casting surface. The said inhomogeneity in skin formation was corresponded to the “waves and lakes” type of casting defect. Such inhomogeneous skin layer limited the ductility of the secondary alloy by undergoing abrupt fracture due to its poor bonding with the adjoining matrix. Even if the AlSi10MnMg(Fe) alloy used in the current research contained an abundance of porosity, cold flakes and intermetallics, which are known to be the driving factors behind the fracture of HPDC processed materials, the effect from the inhomogeneous skin was found out to be predominant.