Advanced Methods

The development of novel types of materials and processes that  take upscaling, safety and sustainability into account requires methodologically state-of-the-art and often long-term research projects. They regularly result into the development of innovative tools for experiments, characterization, processing, simulations and machine learning.

Many important phenomena occurring in polycrystalline materials under large plastic strain, like microstructure, deformation localization and in-grain texture evolution can be predicted by high-resolution modeling of crystals. Unfortunately, the simulation mesh gets distorted during the deformation because of the heterogeneity of the plastic deformation in polycrystals. After reaching high local strain levels, it is no longer possible to continue the simulation, because the mesh distortion reduces the accuracy of the results. In this project we introduce two different adaptive remeshing approaches for simulating large deformation of 3D polycrystals with high resolution under periodic boundary conditions.
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Crystal Plasticity (CP) modeling [1] is a powerful and well established computational materials science tool to investigate mechanical structure–property relations in crystalline materials. It has been successfully applied to study diverse micromechanical phenomena ranging from strain hardening in single crystals to texture evolution in polycrystalline aggregates. more

At finite temperatures lattice vibrations and magnetic fluctuations are coexisting. To study potential coupling effects, a method is required, which considers both, the spin and the lattice degrees of freedom, simultaneously. We develop and implement such a method by combining atomistic spin dynamics with ab initio molecular dynamics. more

A high degree of configurational entropy is a key underlying assumption of many high entropy alloys (HEAs). However, for the vast majority of HEAs very little is known about the degree of short-range chemical order as well as potential decomposition. Due to slow diffusivity, characteristic for e.g. refractory HEAs, chemical ordering is hardly ever approached under typical experimental conditions but could potentially influence creep properties long-term applications. In this project we study the phase stability and short-range order of selected refractory HEAs computationally. more

A novel design with independent tip and sample heating is developed to characterize materials at high temperatures. This design is realized by modifying a displacement controlled room temperature micro straining rig with addition of two miniature hot stages. more

The Atom Probe Tomography group in the Microstructure Physics and Alloy Design department is developing integrated protocols for ultra-high vacuum cryogenic specimen transfer between platforms without exposure to atmospheric contamination. more

Complex simulation protocols combine distinctly different computer codes and have to run on heterogeneous computer architectures. To enable these complex simulation protocols, the CM department has developed pyiron. more

The project focuses on development and design of workflows, which enable advanced processing and analyses of various data obtained from different field ion emission microscope techniques such as field ion microscope (FIM), atom probe tomography (APT), electronic FIM (e-FIM) and time of flight enabled FIM (tof-FIM). more

This work led so far to several high impact publications: for the first time nanobeam diffraction (NBD) orientation mapping was used on atom probe tips, thereby enabling the high throughput characterization of grain boundary segregation as well as the crystallographic identification of phases. more

Combining concepts of semiconductor physics and corrosion science, we develop a novel approach that allows us to perform ab initio calculations under controlled potentiostat conditions for electrochemical systems. The proposed approach can be straightforwardly applied in standard density functional theory codes. more

The balance between different contributions to the high-temperature heat capacity of materials can hardly be assessed experimentally. In this study, we develop computationally highly efficient ab initio methods which allow us to gain insight into the relevant physical mechanisms. Some of the results have lead to breakdown of the common interpretation of temperature dependencies. more

ECCI is an imaging technique in scanning electron microscopy based on electron channelling applying a backscatter electron detector. It is used for direct observation of lattice defects, for example dislocations or stacking faults, close to the surface of bulk samples. more

We introduce a new experimental approach to the compositional and thermomechanical design and rapid maturation of bulk structural materials. This method, termed Rapid Alloy Prototyping (RAP), is based on semi-continuous high-throughput bulk casting, rolling, heat treatment and sample preparation techniques. 45 material conditions – i.e. 5 alloys with systematically varied composition, each modified by 9 different aging treatments – were produced and investigated within 35 hours. This accelerated screening of the tensile, hardness and microstructural properties as a function of chemical and thermomechanical parameters allows for the highly efficient and knowledge-based design of bulk structural alloys. more

Automation of combined experimental setup consisting of Inductively Coupled Plasma Mass (ICP-MS) and Scanning Flow Cell (SFC). more

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