Mechanical Properties of High-Energy Ball Milled Nanocrystalline Al Alloys

Nanocrystalline metallic materials [1–3] produced by the high-energy ball milling (HEBM) [4] are reported to be much stronger and apparently less ductile than conventional coarse grained materials. This difference in the properties is attributed to the unique grain structure, defects, defect activity and the arrangement of such features in nanocrystalline materials. For example, a paucity of dislocations in nanocrystalline materials is well documented. Dislocation pile-up in deformed specimen has not been reported so far and any dislocation activity is primarily believed to originate and terminate at grain boundaries. Due to the fine grain size, grain boundary sliding and/or Coble creep can dominate deformation, which may cause softening. Various aspects of mechanical properties of nanocrystalline materials produced via several processing routes are discussed in the literature. This chapter is focused on mechanical properties of nanocrystalline Al alloys as prepared by HEBM.