Diffusion phenomena in nano-crystalline Cu produced by severe plastic deformation

纳米晶体材料自80年代初被发明以来，由于其依赖于增加晶界的有益特性而吸引了越来越多的兴趣。在不同的生产路线中，等通道角挤压（ECAP）是一种极具吸引力的制备大块超细颗粒材料的方法。认为非平衡晶界是由ECAP过程产生的。然而，这些材料的动力学性质几乎没有被研究过。与传统的粗粒度粒子相比，沿晶界扩散的速度究竟有多快？结构和动力学性质之间的关系是什么？这些和类似的问题将在拟议的项目中得到解决。该项目的重点将是对ECAP生产的纳米晶Cu和Cu- zr合金中Cu、Ag和Ni示踪剂的晶界扩散进行仔细而广泛的放射性示踪剂研究。实验将辅以高分辨率透射电子显微镜分析。为了实现这一目标，需要获得可靠的ECAP材料内部界面动力学和热力学性质的实验数据。

Since their invention in early eighties, nano-crystalline materials attract growing interest in view of their beneficial properties that rely on an increased amount of grain boundaries. Among different production routes, the Equal-Channel Angular Pressing (ECAP) is an attractive method to prepare bulk ultra-fine-grained materials. It is argued that non-equilibrium grain boundaries are created by the ECAP procedure. However, the kinetic properties of such materials are almost not investigated. How fast is the diffusion along grain boundaries in comparison to their conventional coarse-grained counterparts indeed? What is the relation between the structure and the kinetic properties? These and similar problems will be solved in the proposed project. The key point of the project will be a careful and extensive radio tracer investigation of grain boundary diffusion of Cu, Ag, and Ni tracers in nano-crystalline Cu and Cu-Zr alloys produced by the ECAP. The experiments will be complemented by analytical high-resolution transmission electron microscopy. As the goal, reliable experimental data should be derived on the kinetic and thermodynamic properties of internal interfaces in ECAP materials.