Research Projects

Research Projects

Running Projects

In order to solve key challenges in lightweight transportation and safe infrastructures stronger steels with high ductility are urgently needed. In this work we introduce a new unique chemical boundary engineering (CBE) approach, which enables us to create a material with an ultrafine hierarchically heterogeneous microstructure even after heating to high temperatures. more
Within this project we show that medium Mn steels can develop a pronounced discontinuous yielding when the austenite matrix fraction lies about 65 vol%. This phenomenon is investigated by a combination of multiple in situ characterization techniques covering the macroscopic down to the nanoscopic scale. more
We introduce here a new approach in which we strengthen a low-density solid solution matrix simultaneously by a dual-nanoprecipitation system containing both kappa-carbides and B2 particles. Since the conventional thermodynamic working point is not accessible to realize this dual-precipitation strategy, we designed a low-density (6.6 g/cm3) steel-type alloy, which uses merits of the recently introduced multi–principal element approach referred to as compositionally complex alloys (CCAs) or high-entropy alloys (HEAs).

Steels are backbone materials of civilization since more than 3000 years. They retrieve their properties not from expensive chemical compositions but rather from complex nano- and microstructures. They cover a wider spectrum of properties than any other material. more
 In this project, we reveal the subtle yet important interplay between the faceting of grain boundaries and their chemical decoration with solutes in an engineering Al-Zn-Mg-Cu alloy. Previously, the interplay of chemistry and faceting was revealed for specific grain boundaries in well-defined bicrystals, which are realistically not encountered in engineering alloys. more
In this project we investigate tensile fracture mechanisms of medium Mn steels with two typical types of microstructures. One group consists of ferrite (α) plus austenite (γ) and the other one of a layered structure with an austenite-ferrite constituent and δ-ferrite. more
In this project we show that medium Mn steels with an austenite matrix (austenite fraction ~65 vol%) can exhibit pronounced discontinuous yielding. A combination of multiple in situ characterization techniques from macroscopic (a few millimeters) down to nanoscopic scale (below 100 nm) is utilized to investigate this phenomenon. more
In this ongoing project, we investigate spinodal fluctuations at crystal defects such as grain boundaries and dislocations in Fe-Mn alloys using atom probe tomography, electron microscopy and thermodynamic modeling [1,2]. more

Finished Projects

Limitations in the characterization of the partitioning of multiphase alloys, which takes place at the submicron scale, lead to a microstructure optimization of these alloys typically based on the evaluation of the averaged response referred to the macroscopic stress-strain-curves. We introduce a novel experimental-numerical methodology to strengthen the integrated understanding of the microstructure and mechanical properties of these alloys. more
This project is about the understanding and optimization of the microstructure and properties of thin strip cast austenitic stainless steel (AISI 304, 1.4301). Concerning the processing steps the relevance of different thin strip casting parameters, in-line forming operations, and heat treatments for optimizing microstructure and properties have been studied. more
For this project three ferrite/martensite dual-phase steels varying in the ferrite grain size (12.4, 2.4 and 1.2 um) but with the same martensite content (30 vol.%) were produced by large-strain warm deformation at different deformation temperatures, followed by intercritical annealing. more
For this project two plain carbon steels with varying manganese content (0.87 wt pct and 1.63 wt pct) were refined to approximately 1 um by large strain warm deformation and subsequently subjected to intercritical annealing to produce an ultrafine grained ferrite/martensite dual-phase steel. The influence of the Mn content on microstructure evolution is studied by scanning electron microscopy (SEM). more
Austenite reversion during tempering of a Fe-13.6Cr-0.44C (wt.%) martensite results in an ultra-high strength ferritic stainless steel with excellent ductility. more
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