Lattice Misorientation Evolution and Grain Refinement in Al-Si Alloys Under High-Strain Shear Deformation

The starting alloy microstructure can be tailored to achieve varying degrees of grain refinement and enhance mechanical properties through severe plastic shear deformation during solid-phase processing. Crystal plasticity-based grain misorientation modeling, coupled with systematic pin-on-disk tribometry-based subsurface shear deformation experiments on as-cast Al-xSi alloys (x = 0, 1, 4 at %), was conducted. The post-deformation microstructural analysis, through a combined computational and experimental approach, conclusively shows that the initial volume fraction of the hard Si phase enhances the evolution of local lattice misorientation, leading to efficient grain refinement during severe plastic shear deformation. The shear-deformation–induced nanostructure resulted in more than double the nanoindentation hardness in the processed alloy.