Nano-impact and nanoindentation reveals twin-based toughening mechanisms in protective armour of molluscs

Nature often provides an excellent source of inspiration for the formation of biomimetic engineering materials.
In this new publication, researchers at AGH University of Science and Technology, Kraków, used a combination of Micro Materials unique nano-impact test and rapid nanoindentation mapping to investigate the mechanical properties of monocrystalline calcitic prisms of the Pinna Nobilis shell.

A typical adult Pinna Nobilis shell (left). SEM image of calcite grain indented region (centre) and corresponding reduced elastic modulus distribution (right).

This shell comprises calcite crystals of size a few tens of microns distributed across a range of crystallographic orientations. The shells are both stronger and tougher than would be expected from literature calcite values. Understanding why is potentially key to intelligent design of new engineering materials with improved properties.
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Ribs of Pinna nobilis shell induce unexpected microstructural changes that provide unique mechanical properties | Science Direct