(湖南大學(xué) 物理與微電子科學(xué)學(xué)院，長沙 410082)
摘 要: 利用分子動力學(xué)模擬研究多晶納米絲和單晶鉬納米絲在拉伸形變行為上的差異。結(jié)果表明：單晶納米絲比多晶納米絲具有更高的彈性模量、屈服應(yīng)力和斷裂應(yīng)變，且在拉伸過程中伴隨更多的結(jié)構(gòu)轉(zhuǎn)變和無序化，導(dǎo)致超塑性的出現(xiàn)；多晶納米絲拉伸時的頸縮從應(yīng)力高度集中的晶界開始，結(jié)構(gòu)轉(zhuǎn)變也僅局限于此晶界附近，系統(tǒng)的整體結(jié)構(gòu)幾乎沒有受到影響，且晶界處的高應(yīng)力在控制多晶納米絲的塑性形變和斷裂過程中起著決定性的作用；納米絲拉伸時由應(yīng)力引起的結(jié)構(gòu)轉(zhuǎn)變也是塑性變形的一種重要機(jī)制。
關(guān)鍵字: 鉬納米絲；結(jié)構(gòu)轉(zhuǎn)變；力學(xué)性能；分子動力學(xué)
（1. School of Physics and Microelectronics Science, Hunan University, Changsha 410082, China）
Abstract:Using molecular dynamic simulations, the difference of tensile deformation behavior between the polycrystalline Mo nanowires and single-crystalline counterparts was investigated. The results show that, compared with the polycrystalline nanowires, the single-crystalline nanowires have higher elastic modulus, yield strength and fracture strain, and more local atomic structural evolutions and amorphization exist during tensile strain, which results in the superplasticity behaviors of single-crystalline nanowires. For the polycrystalline nanowires, the necking commences from the grain boundary regions of high stress concentration, and the local atomic structural transitions happen only near these regions. Thus, the degree of structure order is rarely affected with increasing strain. The high stresses found in the grain boundary regions of polycrystalline nanowires clearly play a dominant role in controlling both inelastic deformation and fracture processes in the nanoscale objects. The observed atomic configuration transformation is a stress-induced mechanism accounting for plastic deformation.
Key words: Mo nanowires; configuration transformation; mechanical property; molecular dynamics
Key words: Mo nanowires; configuration transformation; mechanical property; molecular dynamics
