Fabrication of High Strength Hybrid Materials through the Application of High-Pressure Torsion

Abstract

It is well established that bulk nanostructured materials with ultrafine grains can be fabricated through the application of severe plastic deformation (SPD) since this is a promising technique for achieving significant grain refinement in bulk metals. Among the various potential SPD techniques, the most attractive appears to be processing by high-pressure torsion (HPT) because this leads to exceptional grain refinement and to grain sizes that are generally not achieved using other SPD procedures. This report describes very recent attempts to form metal matrix nanocomposites (MMNCs) by processing two dissimilar commercial metals, such as aluminum and magnesium alloys, through the use of HPT at room temperature. After significant evolutions in microstructure during the HPT processing, it is demonstrated that hybrid systems may be successfully fabricated having unique microstructures in the form of multi-layered structures. The evolution of small-scale mechanical properties was examined through the novel technique of nanoindentation and the improvement in plasticity was directly estimated by calculating the strain rate sensitivity after processing by HPT. These results demonstrate the possibility of using HPT processing for the fabrication of MMNCs having exceptional properties including very high strength.