Near-Ideal Strength in Gold Nanowires Achieved through Microstructural Design
Near-Ideal Strength in Gold Nanowires Achieved through Microstructural Design
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DOI：
10.1021/nn900668p
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发表时间：
2009-10-01
期刊：
影响因子：
17.1
通讯作者：
Sansoz, Frederic
中科院分区：
文献类型：
--
作者：
Deng, Chuang;Sansoz, Frederic
晶体固体的理想强度是指在弹性不稳定的假设缺陷的无限尺寸的晶体受到不断增加的负载的应力，实验观察到的直径为几十纳米的金属线通常产生远低于理想强度，因为不同类型的表面。或者结构性的。诸如表面不均匀性或晶界的缺陷起到降低位错成核和不可逆变形所需的应力的作用。然而，在这项研究中，我们报告原子模拟的近理想强度在纯Au纳米线与复杂的小平面结构相关的现实纳米线。采用经典分子动力学模拟方法研究了面心立方Au纳米线的抗拉强度与微结构的关系。我们证明，最大的强度和陡峭的尺寸效应从孪晶界间距最好地实现在锯齿形Au纳米线的平行排列的共格孪晶界沿着轴，和{11（1）棒}表面刻面。在所有纳米线的表面刻面产生了一种新的屈服机制与成核和传播的全位错沿着{001}< 110 >滑移系统，而不是常见的{11（1）过棒}< 112 >部分滑移面心立方金属中观察到的。此外，从表面位错成核到均匀位错成核的转变出现的孪晶界间距降低到临界极限以下的刻面纳米线。因此，发现可以利用特殊的缺陷，以接近理想的强度的金纳米线的微结构设计。
The ideal strength of crystalline solids refers to the stress at elastic instability of a hypothetical defect-free crystal with infinite dimensions subjected to an increasing load, Experimentally observed metallic wires of a few tens of nanometers in diameter usually yield far before the ideal strength, because different types of surface. or structural. defects, such as surface inhomogeneities or grain boundaries, act to decrease the stress required for dislocation nucleation and irreversible deformation. In this study, however, we report on atomistic simulations of near-ideal strength in pure Au nanowires with complex faceted structures related to realistic nanowires. The microstructure dependence of tensile strength in face-centered cubic Au nanowires with either cylindrical or faceted surface morphologies was studied by classical molecular dynamics simulations. We demonstrate that maximum strength and steep size effects from the twin boundary spacing are best achieved in zigzag Au nanowire made of a parallel arrangement of coherent twin boundaries along the axis, and {11 (1) over bar} surface facets. Surface faceting in All NWs gives rise to a novel yielding mechanism associated with the nucleation and propagation of full dislocations along {001}< 110 > slip systems, instead of the common {11 (1) over bar}< 112 > partial slip observed in face-centered cubic metals. Furthermore, a shift from surface dislocation nucleation to homogeneous dislocation nucleation arises as the twin boundary spacing is decreased below a critical limit in faceted nanowires. It is thus discovered that special defects can be utilized to approach the ideal strength of gold in nanowires by microstructural design.