纳米晶的疲劳力学行为的研究

项目名称： 纳米晶的疲劳力学行为的研究

项目编号： No.10872197

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 汤奇恒

作者单位： 中国科学院力学研究所

项目金额： 40万元

中文摘要： 本项目设计了二种柱状纳米晶Ni材料。 一是均匀晶粒尺寸，另一种为晶粒尺寸为梯度变化的材料。分子动力学模拟结果如下： 晶粒尺寸均匀分布的柱状纳米晶疲劳的模拟结果表明，塑性变形主要通过晶界运动实现的.观察到晶界扩散，Lomer - Cottrell位错锁的形成和晶粒长大。 晶粒尺寸梯度变化的纳米晶循环加载的结果表明，晶粒的旋转是主要的变形机制。滑移系在大晶粒和小晶粒区域同时开动。循环加载的模拟结果与同一样品的拉伸和压缩结果是不同的。 本研究报告也列举了晶体材料Au和Cu的模拟结果。

中文关键词： 纳米晶；分子动力学；疲劳；塑性变形；梯度材料

英文摘要： The columnar nanocrystalline (NC) Ni models of two kinds of grain size distributions are designed, one is an uniform grain size distribution over the simulation system and other is a gradient grain size distribution. The simulation results by molecular dynamics (MD) are summarized as follows: Cyclic loading simulations for model 1 display that the plastic deformation of NC materials is dominated by grain boundary activities. Some phenomena of grain boundary diffusion, the formation of Lomer-Cottrell dislocation lock and grain coalesce are observed。 Cyclic loading simulations for model 2 show that grain rotation is the main mechanism of deformation. The slip systems are also activated in the large and small grain regions simultaneously。These results are different from that of tension and compression loading. For crystal Au and Cu, the simulation results are also presented in this report.

英文关键词： nanocrystalline; molecular dynamics; fatigue;plastic deformation; graded materials