不同晶向金属纳米线拉伸力学性能分子动力学研究

在经典等温分子动力学框架下,采用位移控制加载方式,准静态数值模拟常温金属纳米线单向拉伸,研究了面心立方晶格(FCC)单晶金属铜纳米线的弹塑性力学性能.研究发现,,不同晶向的纳米线拉伸呈现不同变形力学性能,具有不同的屈服性能和等效弹性刚度.晶向拉伸具有最高的屈服强度,晶向次之,晶向屈服强度最小.特别发现晶向屈服应变最大,而晶向和晶向的屈服应变相近,且比晶向屈服应变的一半还要小.不同晶向的等效弹性模量顺序为E>E>E.通过分析晶向不同纳米线对应不同表面情况、变形过程中位错局部结构具有不同的演化方式、位错发射相关的临界分解剪应力不同,解释了纳米线弹塑性变形的机理.

MOLECULAR DYNAMICS STUDY OF THE TENSILE MECHANICAL BEHAVIOR OF METALLIC NANOWIRES WITH DIFFERENT ORIENTATION

The mechanical properties and the extensional deformation of the single-crystalline Cu nanowires with FCC crystal lattice are analyzed. The elastic modulus and yield strength in three different directions of <100>, <110> and <111> are investigated by the quasi-static classic MD (Molecular dynamics) simulation of the nanowires under tension at room temperature. The discuss about the stress-strain relation and the tension -deformation mechanism of the nanowires, which in term of the structure evolution and the resolved shear stress，is carried out. It is found that the <111> Cu nanowires is highest in strength, while the <110> is worst, and the <100> is best in ductility, the <111> and <110> is similar poor Nanowires have different mechanical properties in different tensile directions