【摘要】 孪晶结构的金属纳米线因具有优异的力学性能而受到广泛关注,然而之前的研究对象都为孪晶界垂直于纵轴的孪晶结构纳米线。本文采用分子动力学模拟的方法,研究了孪晶界平行于纵轴方向的Cu纳米线的力学行为。结果发现纳米线的屈服应力随孪晶厚度的减小而不断增大,表明孪晶厚度减小对孪晶结构的Cu纳米线的强度具有显著强化效应。此外,孪晶结构Cu纳米线的塑性变形机制受孪晶厚度的影响。当孪晶厚度>3个原子层时,它们的塑性变形由Shockley偏位错与孪晶界相交主导;当孪晶厚度减小到3个原子层时,Cu纳米线的塑性变形通过晶格畸变和原子重排导致新的晶粒形成来实现。更多还原

【Abstract】 The twin-structured metals nanowires( NWs) have attracted strong interest because of their excellent mechanical properties. However,most of previous studies were focused on those NWs with twin boundary( TB) that were perpendicular to the NWs’ longitudinal axis. In this paper,the mechanical behavior of Cu NWs with a coherent twin boundary parallel to their longitudinal axis was investigated using molecular dynamics simulation. Our results show that the twin-structure nanowires exhibited a strong twin thickness strengthening effect,which leads to their yielding stress continuing to increase as the twin thickness decreases. Yet,the plastic deformation mechanisms of these nanowires were significantly affected by the twin thickness. For the nanowires with relatively thicker twin,their plastic deformation was controlled by partial dislocations intersecting the coherent twin boundary. As the twin thickness decreases into three atomic layers,the plasticity was accommodated by lattice distortion and rearrangement that led to the twin-structure lattice being transferred into a single-crystal.更多还原