Advanced Study Group Diffusion and Microstructure Analysis (DMA)
|The Advanced Study Group (ASG) Diffusion and Microstructure Analysis (DMA) is located at the Chair for Materials Physics of the Institute of Materials Physics at the Westphalian Wilhelms University Münster. The advanced study group employs a range of complementing experimental analyses methods concerning the underlying physical mechanisms and microstructural origins of macroscopic materials behavior. Specific emphasis is on the coupled analysis of grain boundary diffusion, detailed characterization of the atomic structure of these internal interfaces, and microstructure evolution in deformed materials. Other focus points are related to the analysis of defects and defect interactions by combining electron microscopy on different length scales with calorimetry and atomic mobility analyses. Moreover, nucleation and growth phenomena as well as phase transformations are also in the center of interest. The experimental analyses serve to generate input data for the modeling work on different length scales that is carried out at ICAMS and is further provided for in-depth comparison with and critical verification of the results obtained by computational analyses.Examples for collaboratively addressed topics are:
Microstructure and grain boundary types in ECAP-processed Ni in the course of heterogeneous recrystallization (top) and the penetration profiles of 63Ni as a function of the diffusion time t (bottom).
|The Advanced Study Group Diffusion and Microstructure Analysis is actively involved in the DFG-funded priority program on Strong coupling of thermo-chemical and thermo-mechanical states in applied materials (SPP 1713), which is coordinated at ICAMS and starts in 2014.
Microstructure of ECAP-processed Ni in the as-prepared state (a) and after annealing at 700 K for 17 hours (b); the Arrhenius plot for the measured self-diffusion coefficients D of 63Ni in ECAP-Ni (c). The Ni diffusion rates in ECAP-processed 99.6wt% pure Ni (symbols and solid lines) are shown against Ni grain boundary diffusion coefficients in coarse-grained Ni of 99.6wt% (dashed line) and 99.999 wt% (dashed-dotted line) purities.
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D. Gaertner, J. Kottke, Y. Chumlyakov, F. Hergemöller et al. Tracer diffusion in single crystalline CoCrFeNi and CoCrFeMnNi high-entropy alloys: Kinetic hints towards a low-temperature phase instability of the solid-solution? Scripta Materialia, 187, 57-62, (2020)