Hochschule Karlsruhe Hochschule Karlsruhe - University of Applied Sciences
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Hochschule Karlsruhe Hochschule Karlsruhe - University of Applied Sciences

Institute for Digital Materials Research

Research skills

The production of almost every man-made object and material also requires solidification at some point. Metallic alloys belong to the group of materials most commonly used in industrial applications, e.g. in the foundry industry. During the production of castings, solidification of metallic alloy systems occurs, involving many different phases and consequently different phase transitions. The solidification is accompanied by a complex microstructure formation. Depending on the process conditions and the material parameters, different morphologies can be observed in these microstructures during growth. The specific solidification process has a strong influence on the material properties and the quality of the castings. To improve the material properties in industrial production, the detailed understanding of the dynamic evolution of grain and phase boundaries during the solidification process is of great importance for practical needs. In real metal alloys, the solidification process cannot be observed in situ, so mathematical modelling and numerical simulations can provide valuable information about the formation of the microstructure and make it possible to make predictions about the properties of the developing morphology. Computational modelling is generally intended to design material with specific properties and improve production processes.

For this reason, the basic research activities of our research group focus on modelling and on numerical simulations of solidification and microstructure formation for real metallic alloys and other materials. Special attention is paid to the description of phase transformation processes in multi-component multi-phase systems, taking into account mass and heat diffusion, convection, anisotropy and elasticity. Another goal is the analytical and numerical investigation of multi-scale solidification phenomena occurring on different time and length scales. Our research group is highly interdisciplinary and includes materials science, mathematics, physics and computational sciences.

Credit and information about the parallel 3D simulation solver can be found here: PACE3D (Parallel Algorithms for Crystal Evolution in 3D).

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Research Skills

Modelling and simulation techniques in materials science

  • Thermodynamically consistent phase field modelling (PFM)
  • Asymptotic analysis of sharp interfaces
  • Numerical fluid mechanics: Navier-Stokes and Lattice-Boltzmann solvers
  • Coupling thermodynamic databases with PFM
  • Numerics of partial differential equations: Finite difference and finite element methods
  • Explicit and implicit time discretisations
  • 3D visualisation of microstructures (OpenGL)

Multi-scale modelling and simulation

  • Coupling MD and PF simulations: from an atomistic nucleus to a mesoscopic microstructure
  • Transfer of thermodynamic data from MD simulations as input for PFM
  • Using free energies and structural parameters from DFT calculations as input for PFM
  • Coupling mesoscopic PF simulations and macroscopic calculations: Derivation of microstructure-property correlations, depending on process parameters
  • Formulation of hybrid models and homogenisation methods
  • Adaptive modelling
  • Adaptive numerical methods in terms of time and length scales
  • Parallelisation with MPI on high-performance computers
  • Optimisation of computation time and memory consumption

Applications in materials science

  • Structure formation and phase transitions in multiphase alloy systems
  • Cooling processes: dendritic, eutectic, peritectic and monotectic solidification
  • Kinetics of phase boundaries
  • Diffusion in multicomponent material systems
  • Simulation of characteristic morphologies and quantities of microstructure
  • Polycrystalline grain structures, grain growth, grain coarsening and grain size distributions
  • Dynamics of interfaces, multiple junctions and investigation of the influence on material properties
  • Anisotropy of kinetics and surface energies
  • Modelling of elasticity and plasticity
  • Micromagnetism
  • Multiscale simulations
  • Influence of fluid flow on microstructure formation
  • Mechanisms of nucleation
  • Optimisation of material properties by computer simulations for different process conditions and alloy compositions

Experimentelle Themen: Metallurgie

  • Characterisation of microstructures and their properties
  • Metallographic analysis
  • Measurement of microhardness, surface roughness, etc.
  • Determination of dendrite arm spacing, phase fractions, sizes and shapes, concentration profiles, etc.

 

Other topics

  • Installation of a three-dimensional simulation and visualisation environment (CAVE)
  • Development of a driving simulation software
  • Construction of actuators with haptic feedback for automotive cockpits and for clinical tests of sensor-actuator systems