Annihilation of free volumes and residual strain in nanocrystalline metal layers

本项目的主题是对材料中以下物理过程的基本理解和相互关系：（1）残余应变的弛豫，（2）空位浓度的时间变化，（3）晶粒的结构重新取向，以及（4）自扩散过程。空位浓度，残余应变，和结构重新取向的时间分辨（分钟）的测定是用新开发的同步加速器的差分衍射法。在那里，晶格参数和膜厚度的测量（准）同时在原位等温退火过程中通过X射线衍射仪和X射线反射计。在稳定的纳米结构中的自扩散（在晶粒和晶界）的调查完成与同位素多层膜上的聚焦中子反射计。为了获得可靠的结果比较，所有实验都在相同类型的样品上进行。计划中的基础研究将有助于了解纳米晶体金属的微观结构和应力控制过程，也将有助于优化这些材料的性能。

Topic of the present project is the basic understanding and mutual correlation of the following physical processes in materials: (1) relaxation of residual strain, (2) temporal change of vacancy concentration, (3) structural re-orientation of grains, and finally (4) self-diffusion processes. The time-resolved (minutes) determination of vacancy concentration, residual strain, and structural re-orientation is done with the newly developed method of Synchrotron based differential dilatometry. There, the lattice parameters and the film thickness are measured (quasi-)simultaneously in-situ during isothermal annealing by X-ray diffractometry and X-ray reflectometry. Investigation of self-diffusion (in grains and grain boundaries) in a stable nano-structure is accomplished with focusing neutron reflectometry on isotope multilayers. In order to obtain a reliable comparison of results, all experiments are carried out on the same type of samples. The planned fundamental research will help to understand microstructural and stress controlled processes in nano-crystalline metals and will also help to optimize the properties of these materials.