ICAMS / Interdisciplinary Centre for Advanced Materials Simulation

Diffusion in Metals and Minerals

Julia Kundin
The activities of Diffusion in Metals and Minerals group mainly include modeling complex diffusion processes in metals and minerals on micro and meso scales described by continuum methods, e. g. by diffusion equations combined with phase-field theory. In this regard, our group deals with some critical phenomena such as grain growth, pore evolution, grain boundary diffusion and recrystallization considering various factors such as inclusions, impurities, segregation on the grain boundary and elastic stresses.

One of our research areas is about grain growth in ceramics which is accompanied by the pore evolution and grain boundary diffusion of dopants. Another aspect of our research concerns Kirkendall porosity occurring during interdiffusion in multi-component alloys resulting in the change of the mechanical properties. Once talking about minerals, simulation of texture evolution throughout solidification processes in the presence of the diffusion and convection effects in liquid phase as well as nucleation events are of critical importance. All these processes in complex multi-phase systems can be modeled by combination of different types of phase-field models and relevant diffusion models utilizing the modern thermodynamic and kinetic databases for evaluation of diffusion parameters. The achieved numerical studies are supported by experimental data provided by the leading laboratories in Germany.

Current Projects

Developing the automated assessment software for atomic mobility parameters and hereby establish the kinetic database for HEA alloys. These database together with the thermodynamic databases will be checked by the simulation of the diffusion couple experiments. In order to understand the influence of the vacancy fluxes on the assessment of the diffusion coefficients, the simulation of the interdiffusion with vacancy flux will be carried out on an example of the CrFeNi system.

Application of phase-field simulation of solidification and texture evolution to diffusion chronometry to create a deep understanding of the growth mechanisms and texture formation during the growth and dissolution of olivine crystals in magmatic melts. We also implement newer developments in phase-field modeling that are more relevant for mineralogical systems, such as the exploration of the role of anisotropy of surface / interfacial energies in non-cubic systems. During this study, the texture characteristics (crystal size distribution analysis, crystal shape) and compositional changes taken from the experiments will be compared with the modeling results. Furthermore, the analysis of the lifetime of particular crystals will be carried out.

Prediction of the inhibition effect of dopants on grain growth at high temperatures in alumina minicomposites. The simulations of the abnormal grain growth with diffusion of the dopants along grain boundaries are carried out in 2D and show a good agreement with experiment. Further development of the model to three dimensions will allow us to make more reliable quantitative predictions of the grain size distribution with different matrix dopant concentration under extreme heat treatment conditions.

Investigation of Kirkendall porosity in diffusion couples to achieve high strength, and damage tolerant behavior of Ni-base superalloys and minimize the porosity and their effect, which depends on the pore morphology. The aim of this project is understanding the sequence and physics of multistep morphological evolution of Kirkendall porosity during interdiffusion in nickel-base superalloys. These goals can be fulfilled by combining experiments and phase-field simulations, in order to bridge the different involved effects.


Results of the atomic parameter assessment: calculated and experimental tracer diffusion coefficient of Fe in FeNi alloys. Click image to enlarge.


Growth of olivine crystals in magma. Click image to start animation (5MB).

Competences

  • Phase-field modeling for diffusion chronometry in magmatic systems
  • Grain-boundary diffusion in polycrystalline materials
  • Automated assessments of atomic mobility parameters
  • Pair-wise diffusion model
  • Diffusion couple modeling
  • Phase-field modeling of Kirkendall effect



Group Members

 

Contact

Dr. Julia Kundin
Department of Scale Bridging Thermodynamic and Kinetic Simulation
ICAMS
IC 02/703
Ruhr-Universität Bochum
Universitätsstraße 150
44801 Bochum
Germany

Tel: +49 234 32 29376

Email: julia.kundin@rub.de

 

Recent publications

K. Abrahams, S. Zomorodpoosh, A. Riyahi khorasgani, I. Roslyakova et al. Automated assessment of a kinetic database for fcc Co-Cr-Fe-Mn-Ni high entropy alloys Modelling and Simulation in Materials Science and Engineering, 29, 055007, (2021)

J. Kundin, H. Farhandi, K. P. Ganesan, R.S.M. Almeida et al. Phase-field modeling of grain growth in presence of grain boundary diffusion and segregation in ceramic matrix mini-composites Computational Materials Science, 190, 110295, (2021)

J. Kundin, I. Steinbach, K. Abrahams, S. V. Divinski. Pair-exchange diffusion model for multicomponent alloys revisited Materialia, 16, 101047, (2021)

X. Zhang, B. Mao, L. Mushongera, J. Kundin et al. Laser powder bed fusion of titanium aluminides: An investigation on site-specific microstructure evolution mechanism Materials and Design, 201, 109501, (2021)

J. Kundin, R. S. M. Almeida, H. F. M. A. Salama, H. Farhandi et al. Phase-field simulation of abnormal anisotropic grain growth in polycrystalline ceramic fibers Computational Materials Science, 185, 109926, (2020)


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