Influence of microstructure on the flow behaviour of metallic materials inside micro- and nanocavities - Nanoimprinting

• Applicant: Professor Dr.-Ing. Karsten Durst
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 282202710

Within this project the plastic flow behavior of metals inside micro- and nanocavities is studied. The concept of the proposal is based on nanoimprinting methods, which are applied here to metals. During nanoimprinting a flat punch diamond with cavities is pressed onto the metal and plastic flow processes inside the cavities lead to surface structuring. The scientific program is concerned with how single or multiple grains flow inside small scale cavities during an imprinting process. We aim to use a multiple length scale approach, based on both experiments and simulations to study how the flow process depends on the size of the forming tool with respect to the grain size of the material. By using a systematic variation of grain size, film thickness and work hardening behavior of the material together with various cavity tool dimensions, it is envisaged to lay the scientific basis for controlling the flow behavior at different length scales. Starting from nanocrystalline thin coatings up to fine grained bulk metals, a wide range of grain sizes and film thicknesses is being considered. The deformation mechanism (dislocation motion, subgrain formation, strain gradients, grain boundary sliding, grain rotation) leading to the formation of the extruded material as well as the extrusion height will be analyzed by means of electron microscopy. In-situ deformation experiments inside the electron microscope together with finite element modelling will lead to new insights into the plasticity mechanism. The detailed analysis of the deformation mechanism at different length scales and for various ratios of grain size to cavity size, will be used to develop a deformation mechanism map for microflow processes. The results can give important new insights for applications in the field of surface structuring or the forming of microparts, using metal forming processes.

• DFG Programme: Research Grants