Brittle nanocrystalline metals can be made ultrastrong and tough by firing them at extremely high speeds onto a hard target, according to new experiments on silver microcubes by researchers at Rice University and the University of Massachusetts at Amherst. The impact produces an extreme gradient-nano-grained (GNG) structure in the microcubes that has a grain size varying from nanocrystalline to coarse-grained and it is this variation that makes the material both strong and tough. The work could lead to new techniques for creating GNG-structured metals that do not mechanically fail, like those needed in aircraft and spacecraft for example………
http://nanotechweb.org/cws/article/tech/66687
