Dislocations, Plasticity, and Strain Hardening in Carbon Nanotubes

碳纳米管d中的位错、塑性和应变硬化。C. chrzan，加州大学伯克利分校材料科学与工程系，CA 94720-1760[摘要]碳纳米管具有不同寻常的高拉伸强度和刚度，断裂应力高达30gpa。虽然碳纳米管的弹性特性已经被很好地理解，但碳纳米管的塑性特性仍然不确定。有趣的是，碳纳米管有望通过位错偶极子的成核（Stone-Wales缺陷）、这些偶极子的解离以及随后的位错运动来实现塑性变形。Stone-Wales缺陷的地层能量估计差异很大，可能是因为它们的地层能量受到缺陷之间弹性相互作用的影响。我们将使用周期性位错阵列的弹性理论解来分析基于密度泛函理论的总能量方法得到的缺陷形成能量。这一分析将得出位错的核心半径，并最终得出纳米管中位错的可转移理论。该理论可用于模拟碳纳米管在各种载荷条件下的塑性。

Dislocations, Plasticity, an Strain Hardening in Carbon NanotubesD. C. ChrzanDepartment of Materials Science and EngineeringUniversity of CaliforniaBerkeley, CA 94720-1760AbstractCarbon nanotubes display unusually high tensile strengths and stiffnesses, and breaking stresses as high as 30 GPa have been reported. While the elastic properties of carbon nanotubes are well understood, the plastic properties of carbon nanotubes remain unsettled. Intriguingly, carbon nanotubes are expected to deform plastically through the nucleation of dislocation dipoles (Stone-Wales defects), the dissociation of these dipoles, and the subsequent motion of the dislocations. Estimates of the formation energy for Stone-Wales defects vary widely, perhaps because their formation energy is influenced by elastic interactions between the defects. We will use elasticity theory solutions for periodic dislocation arrays to analyze defect formation energies obtained from density functional theory based total energy methods. This analysis will yield core radii for the dislocations and ultimately, a transferable theory of dislocations in nanotubes. This theory can then be applied to model plasticity in carbon nanotubes under a variety of loading conditions.