Impact of the Microstructure of Refractory Metals on their Mechanical Properties – a Multi-Scale Study

Abstract

Abstract High-performance materials play a dominant role in modern society. Without them, modern manufacturing and transportation technologies would, for instance, be impossible. In order to purposefully improve and optimize the potential of these materials based on their properties, a multi-scale understanding of the interaction of microstructural elements and mechanical properties is essential. Such understanding can be achieved by the specific analysis of the interaction of microstructural components such as interfaces, crystal structures, precipitates, and other defects in the material, as well as of their impact on the underlying deformation processes in complex alloys. For this purpose, not only a precise metallographic preparation of the individual microstructural constituents is performed but also, and in particular, rate- and temperature-dependent plastic deformation processes are determined. On the one hand, this is done on a local scale using micromechanical examination methods such as nanoindentation or uniaxial micropillar-compression experiments. On the other hand, experiments on the global scale with compression and tensile tests are performed. These mechanical characteristics are subsequently correlated with structural and chemical high-resolution analyses based on electron microscopy and atom probe tomography methods. Thus, reliable mechanistic models of the dominating deformation mechanisms of high-performance materials can be created based on these examinations – even under harsh conditions such as elevated temperatures or aggressive environment. This targeted correlative interaction of metallography, high-resolution microstructural analysis, and mechanical deformation experiments is demonstrated by the examples of the refractory metals Mo and Cr as well as on a Mo-Hf-C alloy.