Nanotwin-governed toughening mechanism in hierarchically structured biological materials.
Nanotwin-governed toughening mechanism in hierarchically structured biological materials.
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分级结构生物材料中纳米孪晶控制的增韧机制
DOI：
10.1038/ncomms10772
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发表时间：
2016-02-17
影响因子：
16.6
通讯作者：
Oh SH
中科院分区：
文献类型：
--
作者：
Shin YA;Yin S;Li X;Lee S;Moon S;Jeong J;Kwon M;Yoo SJ;Kim YM;Zhang T;Gao H;Oh SH
作为一种天然的生物复合材料，巨型粉红皇后螺壳具有优异的力学性能，特别是高断裂韧性。众所周知，海螺壳的基本构造块包含高密度的生长孪晶，平均厚度为几纳米，但它们对壳的机械性能的影响仍然是一个谜。在这里，我们揭示了一种由海螺壳中的纳米孪晶控制的增韧机制。结合透射电子显微镜下的现场断裂实验、大尺度原子模拟和有限元模拟表明，孪晶界可以通过诱导裂纹尖端周围的相变和形变的离域来有效地阻止裂纹扩展。这种机制导致基本砌块的断裂能增加一个数量级，并通过结构层次对整体结构的断裂能有显著贡献。
As a natural biocomposite,Strombus gigas, commonly known as the giant pink queen conch shell, exhibits outstanding mechanical properties, especially a high fracture toughness. It is known that the basic building block of conch shell contains a high density of growth twins with average thickness of several nanometres, but their effects on the mechanical properties of the shell remain mysterious. Here we reveal a toughening mechanism governed by nanoscale twins in the conch shell. A combination ofin situfracture experiments inside a transmission electron microscope, large-scale atomistic simulations and finite element modelling show that the twin boundaries can effectively block crack propagation by inducing phase transformation and delocalization of deformation around the crack tip. This mechanism leads to an increase in fracture energy of the basic building block by one order of magnitude, and contributes significantly to that of the overall structure via structural hierarchy.