WEB Impact of Strain Tensor on the Microstructure Evolution of Al-Sc-Zr-based Alloy
Al-based alloys are attractive materials for aerospace applications owing to their low density, sufficient weldability and superior strength at room temperature. Severe plastic deformation of a technical AA5024 Al-based alloy is applied to produce an ultrafine grained microstructure (UFG) with multiple nano-scaled coherently embedded nanoprecipitates. Equal channel angular pressing at 300°C for 8 passes was used.
In this work an external stress field was applied on the samples using a universal testing machine. We investigated the effect of subsequent hot treatments under pure shear or uniaxial compression on the precipitate formation, their chemical composition, microstructure evolution and appearance of residual strains and compared the results with annealing of stress-free samples. The resulting mechano-chemical coupling on different scales is investigated as a function of the treatment temperature. The samples subjected to pure shear are characterized by larger grains with a bimodal size distribution, in contrast to smaller, homogenous distributed grains in the uniaxial compressed samples. Pure shear and uniaxial compression induce a distinct texture at certain temperatures. The impact of the stress state on nano-precipitate evolution is investigated using high-resolution TEM.