( 浙江大學 力學系， 杭州 310027)
摘 要: 應用分子動力學方法模擬了單晶鎳納米薄膜受單向拉伸破壞的過程， 得出納米尺度單晶鎳薄膜的應力—應變關系、 能量演化曲線和鎳薄膜構型的變化及微損傷的形成和擴展過程。 模擬采用原子鑲嵌勢描述原子間作用， 得到鎳單晶薄膜的彈性模量， 分析了拉伸過程中系統(tǒng)原子能量、 應力變化和外荷載的關系。 結果表明： 納米薄膜的自由表面影響拉伸過程中原子的運動和薄膜整體力學性能， 納米薄膜破壞的幾何特征是原子空位的連接和晶胞缺陷的擴展； 單晶的斷裂接近脆性斷裂， 模擬得到納米薄膜的斷裂強度符合Griffith脆性斷裂的能量平衡理論。
關鍵字: 分子動力學; 鎳; 單向拉伸; 鑲嵌原子法
（ Institute of Solid Mechanics, Zhejiang University,
Hangzhou 310027, China）
Abstract: The failure process of monocrystalline nickel film under tensile stress was simulated with molecular dynamics method. The evolvement of atomic energy and arrangement of atoms in the model, the initiation and expansion of damage and the elastic modulus of monocrystalline nickel were obtained. Simulation results show that the free surfaces of single crystal take effect on the motion of atoms and mechanical properties of nano crystal. Atomic cavities and the growth of crack in crystal lead to the failure of nano film. The fracture of single crystal is similar to macro brittle rupture, and the fracture strength of the film can be explained well by Griffith's theory of rupture.
Key words: molecular dynamics; nickel; tension; embedded atom method
