Nanoscale Deformation and Toughening Mechanisms of Nacre
Abstract
We found direct evidence that a single-crystal-like aragonite platelet is essentially assembled with aragonite nanoparticles. The aragonite nanoparticles are readily oriented and assembled into pseudo-single-crystal aragonite platelets via screw dislocation and amorphous aggregation, which are two dominant mediating mechanisms between nanoparticles during biomineralization. The heat treatment burned out the biopolymer in nacre, leaving nanoscale holes at the aragonite platelet boundaries and on the platelet surfaces. By directly probing the biopolymer nanostrands using an atomic force microscope, we unveiled that the biopolymer in nacre has the capability to strengthen itself during deformation. An elastic modulus of 10.57 GPa was determined for nacre biopolymer matrix for the first time. Under high strain rate compression, nacre exhibits surprisingly high fracture strength and relatively marked plastic deformation excursion compared with those in the quasi-static loading mode. We discovered a new deformation mechanism that the emission of partial dislocation and the onset of deformation twinning jointly play a dominated role in the increased fracture strength and ductility. This project has supported 1 postdoctoral researcher and 3 PhD students. Five papers have been published or submitted for publication in prestigious referred journals. The work has been presented at 16 international conferences.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 31, 2011
- Accession Number
- ADA545751
Entities
People
- Xiaodong Li
Organizations
- University of South Carolina