dislocation nucleation; nanograin; nanophenomena
It is well known that metals are hardened by deformation and soften by annealing. How about nanostructured metals? Can we reply on conventional metal-working lore? In a paper in Science (Huang et al., Science, 312 (2006) 249), Xiaoxu Huang and colleagues at the Riso National Laboratory, Denmark and Osaka University, Japan have found that nanostructured aluminum behaves in contrast to the conventional theories; annealing makes it stronger and tougher whereas deformation (cold working) gains ductility with a trade-off of lowering the strength.