10nm以下金属与碳纳米管接触时的塑性变形及其机理研究

纳米金属和碳纳米管能否在机械运动时保持良好的接触，对纳机电系统的高性能运行和可靠性起着至关重要的作用。最新的研究表明：室温下10nm以下金属呈现类液态的变形行为，其塑性变形机制由表面扩散主导，类似于Coble蠕变。这一方面的研究刚刚起步，留有大量不清楚的细节和未解决的问题。本课题拟利用Nanofactory STM-TEM操作平台，在球差校正透射电镜中用碳纳米管挤压拉伸10nm以下金属单体，通过调控应变速率、加载方向、碳纳米管-金属通电互溶、表面污染物等因子，在原子尺度实时观察位错运动、表面扩散、颈缩和弛豫过程，获得不同金属出现类液态变形时的临界尺寸和屈服强度，最后结合分子动力学模拟，给出一个涵盖金属种类、应变速率、加载方向、通电互溶、表面污染物等因素的塑性变形理论框架。课题成果将加深对10nm以下金属塑性变形的理解，并有望制造出基于碳纳米管-金属的柔性连接，应用在纳机电系统中。

Whether nanometals and carbon nanotubes can maintain good contact during mechanical motion plays a crucial role in the high-performance operation and reliability of nanoelectromechanical systems. The latest research shows that sub-10-nm metals exhibits liquid-like deformation behavior at room temperature, and its plastic deformation mechanism is dominated by surface diffusion, similar to Coble creep. Research in this area has just begun, leaving a large number of unclear details and unresolved issues. This study intends to utilize Nanofactory STM-TEM operating platform to compress and stretch sub-10-nm metals with carbon nanotubes in a spherical aberration corrected transmission electron microscope. By controlling the strain rate, loading direction, current induced dissolution between carbon nanotube and metals, surface contamination, etc., the dislocation movement, surface diffusion, necking and relaxation process are observed at the atomic scale in real time. The critical size for liquid-like deformation and yield strength for different metals type are obtained. Finally, combined with molecular dynamics simulation, a theoretical framework of plastic deformation will be proposed, which covers the factors such as metal type, strain rate, loading direction, current induced dissolution, surface contamination and other factors. The results will deepen the understanding of plastic deformation in sub-10-nm metals. It is expected to produce flexible carbon nanotube-metal connection that can be used in nanoelectromechanical systems.