Confined spinodal fluctuations at crystal defects evidenced in Fe-Mn alloys
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].
Analysis and design of materials and fluids requires understanding of the fundamental relationships between structure, composition and properties. Dislocations and grain boundaries influence microstructure evolution through the enhancement of diffusion and by facilitating heterogeneous nucleation, where atoms must overcome a potential barrier to enable the early stage of formation of a phase. Adsorption and spinodal decomposition are known precursor states to nucleation and phase-transition, however nucleation remains the less well understood step in the complete thermodynamic sequence that shapes a microstructure. Here, we report near-atomic-scale observations of a phase transition mechanism which consists of solute adsorption to crystalline defects followed by linear and planar spinodal fluctuations in a Fe-Mn model alloy. These fluctuations provide a pathway for austenite nucleation due to the higher driving force for phase transition in the solute-rich regions. Our observations are supported by thermodynamics calculations, which predict the possibility of spinodal decomposition due to magnetic ordering.
International researcher team presents a novel microstructure design strategy for lean medium-manganese steels with optimized properties in the journal Science
In this project, we aim to realize an optimal balance among the strength, ductility and soft magnetic properties in soft-magnetic high-entropy alloys. To this end, we introduce a high-volume fraction of coherent and ordered nanoprecipitates into the high-entropy alloy matrix. The good combination of strength and ductility derives from massive solid…
Thermoelectrics have attracted increasing attention as a sustainable and flexible source of electricity able to meet a wide range of power requirements. Their application is wide as they could be used as main source of electricity as in satellites or used to increase efficiency of thermal processes in industries or cars or any other application…
In this EU Horizon project, we at MPIE, will focus on the sustainable pre-reduction of manganese ores with hydrogen, especially the kinetic analysis of the reduction process using thermogravimetry analysis and an in-depth understand the role of microstructure and local chemistry in the reduction process.
Understanding the deformation mechanisms observed in high performance materials, such as superalloys, allows us to design strategies for the development of materials exhibiting enhanced performance. In this project, we focus on the combination of structural information gained from electron microscopy and compositional measurements from atom probe…
Deviations from the ideal, stoichiometric composition of tcp (tetrahedrally close-packed) intermetallic phases as, e.g., Laves phases can be partially compensated by point defects like antisite atoms or vacancies, but also planar defects may offer an opportunity to accommodate excess atoms.
We plan to investigate the rate-dependent tensile properties of 2D materials such as HCP metal thin films and PbMoO4 (PMO) films by using a combination of a novel plan-view FIB based sample lift out method and a MEMS based in situ tensile testing platform inside a TEM.