The Department of Disperse Phase Transformation Processes is an associated research group that is legally and organizationally affiliated with the University of Bremen.
It focuses on technical processes in which droplets and particles change their states of matter. Examples include atomization processes, in which droplets solidify into particles, or additive manufacturing, in which particles fuse together through heat. To gain a deeper understanding of these transformation processes, the department works with isolated sub-processes and process modeling.
Key research areas include:
- Generic model experiments with single droplets
- Determination of thermophysical material properties
- Modeling of processes involving phase transformation phenomena
- Development of sustainability strategies
- Atomization processes for metallic melts
- Advanced Materials
![[Translate to English:] Schwarz-weiß-Bild von Parikeln imter dem Mikroskop in hoher Vergrößerung](/fileadmin/images/header/Header_Partikel.jpg)
Development of a new process route for the additive manufacturing of high-nitrogen, corrosion-resistant, martensitic steels through the process combination of PBF-LB/M and HIP with integrated rapid quenching
In 2025, numerical analyses with experimental validation of nitrogen behavior during laser beam melting (PBF-LB/M) of corrosion-resistant steels were conducted. Our overarching goal remains to gain a thorough understanding of the complex desorption behavior of supersaturated nitrogen in order to enable targeted control of the material properties of N-alloyed steels.
By coupling the Discrete Element Method (DEM) with the Finite Volume Method (FVM) in OpenFOAM, we were able to develop and validate a model that accurately represents both diffusive and convective transport as well as desorption at the free surface. In particular, the findings on the Sherwood number as a key parameter for mass transfer mark a significant advance.
Looking ahead, these results promise to improve component quality and resource efficiency in industries such as medical technology and aerospace. The next focus is on the validation of complex multi-layer simulations at the NHR, in order to close the gap between single-track studies and industrial manufacturing.
Cooperation: University of Bremen MVT / Ruhr University Bochum LWT
Funding: DFG
Single track with powder X30Cr15N for P = 150 W, v = 900 mm/s and h = 70 μm in a) the cross-sectional view of the nitrogen content and b) the local sink term for nitrogen loss at the free surface of the melt pool.
![[Translate to English:] Grafische farbige Darstellung zum Stickstoffgehalt](/fileadmin/images/content/forschung/verfahrenstechnik/AddMarN_Bild_1.png "AddMarN_Bild_1")
![[Translate to English:] Grafische Darstellung](/fileadmin/images/content/forschung/verfahrenstechnik/AddMarN_Bild_2.png "AddMarN_Bild_2")
The project focuses on the additive manufacturing of high-strength low-alloy steels (HSLA) by means of laser metal deposition, with the aim of analyzing the influence of different powder strategies as well as process- and heat-treatment-related parameters on the microstructure and mechanical properties of these HSLA steels.
The work encompasses the processing of pre-alloyed powders as well as mixtures of binary iron-based alloys. The results show that the choice of powder strategy has a significant influence on microstructural evolution and property homogeneity. While the powder mixtures investigated can lead to local inhomogeneities, pre-alloyed powders enable a finer and more uniform microstructure. Subsequent heat treatment makes it possible to achieve hardness distributions at technically relevant levels throughout the entire sample volume.
These results underline the potential of laser metal deposition for the flexible manufacturing of high-performance HSLA components. Building on this, further development opportunities arise, particularly with regard to scaling the process and the targeted adjustment of local property profiles for future industrial applications.
Cooperation: University of Bremen, Leibniz-IWT WT-WB, MAPEX
Funding: DFG 434424600
![[Translate to English:] Homogenisierende Wärmebehandlung einer aus vorlegiertem Pulver hergestellten HSLA-Probe](/fileadmin/images/content/forschung/verfahrenstechnik/HSLA-Staehle_Haerteverlauf.png)
This project advances the development of high-performance metallic carriers for energy storage and chemical looping applications. Using a unique high-temperature drop-on-demand droplet generator, we have succeeded in producing metal spheres from pure Fe and FeMn alloys (3%, 5%, 10%, and 20% Mn). This material has enabled our partners at the University of Duisburg-Essen and TU Clausthal to conduct cyclic redox experiments across a wide temperature range.
Our most recent results provide important insights into how the integration of manganese maintains material stability and prevents degradation over time. The goal is to develop a carrier that retains its maximum efficiency even at lower operating temperatures, thereby significantly reducing energy consumption.
In the future, we will investigate further alloy refinements to maximize the number of possible cycles.
Cooperation: University of Duisburg-Essen, Institute for Metal Technologies (ITM), Chair of Metallurgy of Iron and Steel Production; Clausthal University of Technology, Institute of Metallurgy (IMET), Metallurgical Process Technology; Thyssenkrupp Steel Europe AG; SMS group GmbH; Leibniz-IWT VT / WT
Funding: BMBF 03SF0658C (Me2H2)
![[Translate to English:] Drop-on-Demand-Erzeugung von Materialproben](/fileadmin/images/content/forschung/verfahrenstechnik/Eisen_Dampf_Prozess_Tropfengenerator.jpg)