Dislocations, Plasticity, and Strain Hardening in Carbon Nanotubes

碳纳米管中的位错、塑性和应变硬化。C. ChrzanDepartment of Materials Science and EngineeringingUniversity of California Berkeley，CA 94720- 1760摘要碳纳米管显示出异常高的拉伸强度和刚度，并且已经报道了高达30 GPa的断裂应力。虽然碳纳米管的弹性性质已经很好地理解，但碳纳米管的塑性性质仍然不稳定。有趣的是，预计碳纳米管通过位错偶极子（Stone-Wales缺陷）的成核、这些偶极子的解离以及随后的位错运动而塑性变形。 斯通-威尔士缺陷的形成能的估计值变化很大，可能是因为它们的形成能受到缺陷之间的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从基于密度泛函理论的总能量方法获得的缺陷形成能。 这种分析将产生核心半径的位错，并最终，在纳米管中的位错转移理论。 然后，该理论可以应用于各种载荷条件下的碳纳米管的塑性模型。

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.