Nanoscale deformation mechanics reveal resilience in nacre of Pinna nobilis shell.

Jiseok Gim (1) , Noah Schnitzer (1) , Laura M. Otter (2) , Yuchi Cui (1) , Sébastien Motreuil (3) , Frédéric Marin (3) , Stephan E. Wolf (4, 5) , Dorrit E. Jacob (2) , Amit Misra (1) , Robert Hovden (1, 6)

1 Department of Materials Science & Engineering
2 Department of Earth and Planetary Sciences [Sydney]
3 BGS - Biogéosciences [UMR 6282]
4 Department of Materials Science & Engineering
5 FPS - Interdisciplinary Center for Functional Particle Systems
6 Applied Physics Program

The combination of soft nanoscale organic components with inorganic nanograins hierarchically designed by natural organisms results in highly ductile structural materials that can withstand mechanical impact and exhibit high resilience on the macro- and nano-scale. Our investigation of nacre deformation reveals the underlying nanomechanics that govern the structural resilience and absorption of mechanical energy. Using high-resolution scanning/transmission electron microscopy (S/TEM) combined with in situ indentation, we observe nanoscale recovery of heavily deformed nacre that restores its mechanical strength on external stimuli up to 80% of its yield strength. Under compression, nacre undergoes deformation of nanograins and non-destructive locking across organic interfaces such that adjacent inorganic tablets structurally join. The locked tablets respond to strain as a continuous material, yet the organic boundaries between them still restrict crack propagation. Remarkably, the completely locked interface recovers its original morphology without any noticeable deformation after compressive contact stresses as large as 1.2 GPa.

Domaines: Biomatériaux; Mécanique des matériaux [physics.class-ph]

Jiseok Gim, Noah Schnitzer, Laura M. Otter, Yuchi Cui, Sébastien Motreuil, et al.. Nanoscale deformation mechanics reveal resilience in nacre of Pinna nobilis shell.. Nature Communications, 2019, 10 (1), pp.4822. ⟨10.1038/s41467-019-12743-z⟩. ⟨hal-02334050⟩