"Nanotwinned" Metals Display Both Ultrahigh Strength and Ductility

The enigmatic ability of "nanotwinned" metals to display disparate physical properties-ultrahigh strength and ductility-has been explained by YongWei Zhang and David Srolovitz from the A*STAR Institute of High Performance Computing, Singapore, and National University of Singapore graduate student Zhaoxuan Wu. The key lies in understanding how different types of dislocation propagate through nanotwinned metals in a manner not seen in bulk materials.

Metals can be made stronger if they are refined to have very small crystal grains. Unfortunately, these fine-grained metals also lose some of their toughness, meaning that they may break easily when deformed.

In recent years, researchers have discovered that this problem can be partly resolved by introducing nanotwinned crystal grains. At the boundaries between these grains, the atomic structure on one side is a mirror reflection, or ‘twin’, of the other.

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