纳米线高应变率拉伸超塑性  

Super-plasticity of nanowires under high-strain-rate tension

作　　者：路文江[1] 包宏伟[1] 汤富领[1] 蔡后敏 芮执元[2] 朱亮[1] 

机构地区：[1]兰州理工大学材料科学与工程学院,甘肃兰州730050 [2]兰州理工大学机电工程学院,甘肃兰州730050

出　　处：《兰州理工大学学报》2015年第1期15-20,共6页Journal of Lanzhou University of Technology

基　　金：国家科学自然基金(10964003;11164014;11364025)

摘　　要：应用分子动力学方法,采用嵌入势EAM与Buckingham势,对金属Cu、半导体化合物CuInSe2和陶瓷化合物MgO纳米线进行拉伸模拟,考察其拉伸应力-应变曲线,并分析拉伸过程中的结构变化.发现当以高于临界应变率的速率对纳米线进行拉伸时,纳米线由脆性断裂向韧性断裂转变,且其延伸率可以超过100%,表现出超塑性的特性,而以较低应变率拉伸时,纳米线仍然表现为脆性断裂,这表明纳米线材料的超塑性对于应变率高度敏感.通过观察纳米线在拉伸过程中的结构变化,发现高应变率拉伸时由于CuInSe2与Cu纳米线晶体结构发生非晶化,在这一转变过程中大量能量被吸收,因而导致其塑性变好.而MgO纳米线则发生面心立方结构向环形结构的相变,相变的发生同样导致了能量的吸收,从而使其塑性大大改善.Molecular dynamics approach,embedded atom potential method（EAM）,and Buckingham potential were employed to carry out tensile simulation of super-plasticity of nanowires of metal（Cu）,semiconductor（CuInSe2）,and ceramic oxide（MgO）.The stress-strain curves were investigated and the configuration evolution of the nanowires was analyzed.It was found that nanowire would exhibit brittle to ductile transition if it was tensioned with strain rate higher than its critical value and its elongation might exceed 100%,exhibiting super-plasticity.The nanowires would exhibit brittle fracture when the strain rate was lower.This illustrates that super-plasticity of nanowires is high sensitive to strain rate.It was also found by observing the structural change in the process of their extension that for CuInSe2 and Cu nanowires,the higher strain rate would induce non-crystallization transition of nanowires and a great amount of energy might be absorbed during this process.This result would lead to the improvement of the super-plasticity of the nanowires;For MgO nanowires,there would be a phase change from plano-centered cubic configuration to annular one,resulting in energy absorption and great improvement of their plasticity.

关 键 词：纳米线 分子动力学 超塑性 

分 类 号：TG115.28[金属学及工艺—物理冶金]