镍单晶纳米丝单向拉伸的分子动力学模拟

应用分子动力学方法模拟了金属镍单晶纳米丝在无热激活状态下的轴向拉伸变形过程，得出
纳米尺度下单晶镍丝的应力-应变演化关系、能量和原子构型变化以及损伤初始化与扩展过程。通过与宏
观拉伸过程的比较，模拟结果表明表面原子使纳米丝在无外荷载作用时存在系统初始应力，自由表面张力
的作用使纳米丝横截面上存在与轴向应力变化趋势一致的正交等值应力，自由表面发射位错和滑移并形成
堆垛层错和原子台阶导致纳米丝变形；表面原子偏离理想位置形成的空穴和孔洞及其连接是纳米丝损伤破
坏过程的几何特征。模拟获得镍单晶纳米丝的断裂强度为22.96 GPa。

Molecular dynamics simulation of monocrystalline nickel nano-wire under uniaxial tension

Molecular dynamics method was used to obtain the relationship between atomic stress and strain, atom energy variation and arrangement, initiation and expansion of damage in monocrystalline nickel nano-wire under uniaxial tension without heat activation. Compared with continuum tension analysis, simulation results show that atoms on model surfaces lead to initial atomic stress when no external loads exist, tension on free surfaces generates orthogonal and equivalent stresses which change along with the axial stress on cross sections of the wire; dislocation, slip, atom stowage and steps result in the deformation of nano-wire; atom cavities derive from departure of surface atoms from perfect state and their expansion explain geometrically the failure process of the model. The simulation revealed that the fracture strength of nanocrystalline nickel wire was 22.96 GPa.