Research competences

Manufacture of almost every man-made object and material involves solidification at some stage. Metallic alloys are the most widely-used group of materials in industrial applications, for example in the foundry industry. During the manufacture of castings, solidification of metallic alloy systems occurs involving many different phases and hence, various kinds of phase transitions. The solidification is accompanied by a complex microstructure formation. Depending on the process conditions and the material parameters, different growth morphologies can be observed in these microstructures. The specific solidification process has a great influence on the material properties and the quality of the castings. For improving the properties of materials in industrial production, the detailed understanding of the dynamical evolution of grain and phase boundaries during the solidification process is of great importance for practical needs. In real metallic alloys, the solidification process can not in-situ be observed, so that mathematical modelling and numerical simulations provide valuable information of the microstructure formation and may give access for predicting characteristics the evolving morphology. The overall intension of computational modelling is to design material with specific properties and to improve the production processes.

Therefore, the fundamental research activities of our research group are focused on modelling and numerical simulations of solidification and microstructure formation for real metallic alloys and other materials. Special emphases lies on the description of phase transformation processes in multicomponent multiphase systems under the consideration of mass and heat diffusion, convection, anisotropy and elasticity. Another aim is to analytically and numerically study multiscale solidification phenomena occuring on different time and length scales. Our group is of highly interdisciplinary character involving materials science, mathematics, physics and computational sciences.

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

 

Modelling and Simulation Techniques in Materials Science:
 

  • thermodynamical consistent phase-field modelling (PFM)
  • sharp interface asymptotics
  • computational fluid dynamics: Navier-Stokes and Lattice Boltzmann solver
  • coupling of thermodynamical data bases with PFM
  • numerics of partial differential equations: Finite differences and finite element methods
  • explicit and implicit time discretizations
  • 3D visualization of microstructures (OpenGL)


Multiscale Modelling and Simulation:
 

  • coupling of MD- and PF-simulations: From an atomistic nucleus to a mesoscopic microstructure
  • transfer of thermodynamical data from MD simulations as input for PFM
  • use of free energies and structural parameter from DFT-computations as input for PFM
  • coupling of mesoscopic PF-simulations and macroscopic computations: Derivation of microstructure-property correlations depending on process parameters
  • formulation of hybrid models and homogenization methods
  • adaptive modelling
  • adaptive numerical methods with respect to time and length scales
  • parallelization with MPI on high performance computers
  • optimization of computing time and memory usage


Applications in Materials Science:
 

  • microstructure 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 microstructure quantities
  • 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
  • infuence of fluid flow on microstructure formation
  • mechanisms of nucleation
  • optimization of material properties by computer simulations for different process conditions and
  • alloy compositions


Experimental Topics: Metallurgy
 

  • characterisation of microstructures and their properties
  • metallographic analysis
  • measurement of micro hardness, surface roughness, etc.
  • determination of dendrite arm spacings, phase fractions, sizes and shapes, concentration profiles etc.


Other Topics:
 

  • installation of a 3D simulation and visualization environment (CAVE)
  • development of a driving simulation software
  • construction of actuators with haptical feedback for automobile cockpits and for clinic tests of sensor-/actor systems