Extra strengthening and work hardening in gradient nanotwinned metals

Nature provides the key to stronger materials

24 June 2019

Metals can be made stronger and more resilient to fatigue by varying the spacing between nanotwins — tiny boundaries in the lattice patterns of metal atoms with identical crystalline structures on either side, scientists have found.

So-called gradient structures such as bone, shells and trees contain microstructures that provide them with enhanced strength and fatigue resistance compared with gradient-free materials. While materials scientists have mimicked these structures to increase a metal’s strength, flexibility and toughness, understanding their underlying mechanical behaviour has proved challenging.

Now, a team that included researchers from the University of Science and Technology in China has discovered that varying the spacing from 29 to 72 nanometres between nanotwin boundaries in copper dramatically improves its strength and rate of work hardening — the extent to which a metal strengthens when deformed.

The work could lead to new manufacturing techniques for creating high-performance materials.

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References

1. Science 362, 559 (2018). doi: 10.1126/science.aau1925