Superstrength through Nanotwinning
Superstrength through Nanotwinning
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DOI：
10.1021/acs.nanolett.6b03414
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发表时间：
2016-12-01
期刊：
影响因子：
10.8
通讯作者：
Haber, Richard A.
中科院分区：
文献类型：
--
作者：
An, Qi;Goddard, William A., III;Haber, Richard A.
材料的理论强度是使没有缺陷的完美单晶材料变形或断裂的最小应力。该理论强度被认为是真实的晶体可达到强度的上限。与此预期相矛盾的是，我们使用量子力学（QM）模拟表明，对于碳化硼（B4C）硬质陶瓷，通过施加纳米级孪晶，该理论剪切强度可以超过11%。我们还预测，从量子力学的纳米孪晶B4C的压痕强度是12%以上的完美晶体。此外，我们通过实验验证了这种效果，表明纳米孪晶样品比B4C的无孪晶对应物硬2.3%。这种强化机制的起源是由于在TB处的共价键的方向性而抑制纳米孪晶内的孪晶边界（TB）滑移。
The theoretical strength of a material is the minimum stress to deform or fracture the perfect single crystal material that has no defects. This theoretical strength is considered as an upper bound on the attainable strength for a real crystal. In contradiction to this expectation, we use quantum mechanics (QM) simulations to show that for the boron carbide (B4C) hard ceramic, this theoretical shear strength can be exceeded by 11% by imposing nanoscale twins. We also predict from QM that the indentation strength of nanotwinned B4C is 12% higher than that of the perfect crystal. Further, we validate this effect experimentally, showing that nanotwinned samples are harder by 2.3% than the twin-free counterpart of B4C. The origin of this strengthening mechanism is suppression of twin boundary (TB) slip within the nanotwins due to the directional nature of covalent bonds at the TB.