Scientific Events

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In modern society, metallic materials are crucially important (e.g. for applications related to energy, safety, infrastructure, transportation, health, medicine, life sciences, IT). Contemporary examples with inherent challenges to be overcome are the design of ultrahigh specific strength materials. There is a critical need for successful developments in this area in particular for reduced energy consumption, reduction of pollutant emissions and passenger safety. Also, the ageing society makes biomedical materials for implant and stent design crucially important. A drawback of nearly all current high strength metallic materials is that they lack ductility (i.e. are brittle and hard to form) - or on the opposite side, they may be highly ductile but lack strength. Hence, it is mandatory to develop new routes for creation of tailored metallic materials based on hierarchical hybrid structures enabling property as well as function optimization. One starting point along these lines is the design of monolithic amorphous materials or bulk micro-, ultrafine- or nano-structured composite structures with intrinsic length-scale modulation and phase transformation under highly non-equilibrium conditions. This can include the incorporation of dispersed phases which are close to or beyond their thermodynamic and mechanical stability limit thus forming hierarchically structured hybrid and ductile/tough alloys. Alternatively, the material itself can be designed in a manner such that it is at the verge of its thermodynamic/mechanical stability. This talk will present recent results obtained for metallic glass-based hybrid structures with transformation effects at different length-scales and microcrystalline-grained hybrid structures based on elastic instabilities and modulated length-scale. The deformation behaviour and possible phase transitions during deformation will be related to the intrinsic properties of the phases as well as the microstructure of the material including heterogeneities and length-scale modulation in order to derive guidelines for the design of macroscopically ductile high-strength materials. Finally, the results will be critically assessed from the viewpoint of possible scaling-up for technological applications and the use of simple and cost effective processing technologies. [more]

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In many materials, internal interfaces and surfaces are governing their properties. Due to the inherently atomic scale of interfaces, they have notoriously been elusive to structural and chemical analysis, limiting our current understanding about their behavior. Atom probe tomography, as a single atom sensitive mass spectrometry method with atomic resolution achievable, can significantly add to the understanding of interfaces. In this talk, I will present results on the analysis of local chemistry at grain boundaries in metals and oxides and the challenges associated with the data interpretation. This will also include nanomaterials such as nanoparticles and nanowires, where surface distributions of the chemical elements can be investigated and correlated with the particle’s properties. [more]

• advises and supports scientists at Max Planck Institutes in evaluating their inventions and filing patents • mediates the transfer of inventions from Max Planck Institutes to industry • supports scientists at Max Planck Institutes in founding companies [more]

Developing materials for optical and electrical applications often requires an understanding of the relationships between processing and point defects. Atomic scale relationships such as these are frequently elusive to understand due to a lack of characterization techniques. In this work, I will show examples of nanoscale and atomic scale characterization of oxide and semiconductor point defects determined through atom probe tomography (APT). Specifically, oxygen stoichiometries in oxygen and proton conducting oxides can be directly related to the electrical conductivities where grain boundaries dominate transport. Laser assisted APT also allows for unique opportunities for measuring atomic diffusion where thermal transport can assist transformations from metastable states. Using a “Dynamic” atom probe, atomic scale diffusion can be quantified at the atomic scale in 3-dimensions using a combination of APT and in-situ electron diffraction with a temporal resolution of better than 1 ns. An in-situ STEM / APT instrument engineered and constructed at CSM will be detailed as well as opportunities for using such data for improved APT data reconstruction. [more]