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利用分子动力学方法,对本课题组率先采用金属催化的气相合成法制备出的高纯度单晶钨纳米线进行拉伸变形数值模拟,通过分析拉伸应力-应变全曲线及其微观变形结构,揭示出单晶钨纳米线的拉伸变形特征及微观破坏机理.结果表明:单晶钨纳米线的应力-应变全曲线可分为弹性阶段、损伤阶段、相变阶段、强化阶段、破坏阶段等五个阶段,其中相变是单晶钨纳米线材料强化的重要原因;首次应力突降是由于局部原子产生了位错、孪生等不可逆变化所致;第二次应力突降是发生相变的材料得到强化后,当局部原子再次产生位错导致原子晶格结构彻底破坏而形成裂口、且裂口不断发展成颈缩区时,材料最终失去承载能力而断裂.计算模拟得到的单晶钨纳米线弹性模量值与实测值符合较好.
Using molecular dynamics method, the tensile deformation of high-purity single crystal tungsten nanowires prepared by metal-catalyzed gas-phase synthesis method was first simulated by our group. By analyzing the tensile stress-strain curves and their microstructure, The results show that the stress-strain curves of single-crystal tungsten nanowires can be divided into five phases: elastic phase, damage phase, phase transformation phase, strengthening phase and failure phase Phase, of which phase transition is an important reason for the strengthening of single-crystal tungsten nanowires material; the first sudden stress drop is due to local atomic dislocations, twins and other irreversible changes caused by the second stress dip is the occurrence of phase change material When strengthened, the dislocations of partial atoms lead to the complete destruction of the atomic lattice structure and the formation of rips. When the rips continue to develop into necking regions, the material eventually loses its carrying capacity and breaks down. The calculated single crystal tungsten nanowire elasticity Modulus values and measured values in good agreement.