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Home » Institute » Departments & Research Groups » Micromechanical and Macroscopic Modelling » Mechanical Properties of Interfaces

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Department Atomistic Modelling and Simulation
Research Group

Mechanical Properties of Interfaces

The research group “Mechanical Properties of Interfaces” focuses on the fundamental processes occurring at interfaces, which strongly affect the strength and deformability of polycrystalline microstructures in metals and alloys, and their relation to the atomistic structure of the internal boundaries.


Rebecca JanischRUB, Marquard
PD Dr. habil. Rebecca Janisch

Research Group Leader

Room: 02-503
Tel.: +49 234 32 29304
E-Mail: rebecca.janisch@rub.de




Research

These processes are investigated by means of atomistic simulations. Ab-initio electronic structure calculations based on density functional theory are used to predict the energy, strength, and effective modulus of interfaces and other defects in iron and ferritic steel. Such characteristic properties are used to identify and understand trends, e.g. on hydrogen solubility in ferritic microstructures and on its effect on grain boundary cohesion. Thus, guidelines for alloy design and constitutive relationships for multiscale simulations, e.g. of hydrogen-enhanced decohesion, are derived. A combination of atomistic methods with a statistical assessment of the parameter space that defines the structure of grain boundaries allows a larger survey of structures in an efficient manner, which is needed to derive structure-property relationships.

Via large-scale atomistic simulations the fundamental deformation and crack propagation mechanisms in interface-dominated microstructures are determined – such as interfacial sliding, migration, dislocation emission, and twinning in fully lamellar TiAl alloys – and are related to fundamental physical quantities, such as surface and stacking fault energies.

In the last years the group’s projects focused on the role of the excess volume of grain boundaries for the solution of H, the development of an efficient algorithm that combines design of experiment principles with atomistic simulations and the role of defects and crack geometry during fracture of lamellar and polycrystalline TiAl microstructures.


Competences

  • Ab initio electronic structure calculations
  • Molecular dynamics simulations
  • Scale-bridging modelling of interface mechanics and thermodynamics
  • Statistical methods
Bridging the scale: Atoms, microstructures, properties.

Flowchart of the algorithm to sample grain boundary energies, consisting of initial design, sequential design and final Kriging interpolation. The example shown for the final interpolation is the energy in the fundamental zone of grain boundary inclinations for a [110]7.5° grain boundary in fcc Ni.
ICAMS, RUB

Members
  • Etabu, Godwil
  • Janisch, PD Dr. habil. Rebecca
  • Madadi, Makham
  • Meydani, Erfan
  • Sen, Onur
Recent Publications
  • O. Sen, R. Janisch. Crack configuration influence on fracture behavior and stress shielding: insights from molecular dynamics simulations. Modelling and Simulation in Materials Science and Engineering, 32, 065033, (2024)
  • A. Chauniyal, P. Thome, M. Stricker. Employing constrained nonnegative matrix factorization for microstructure segmentation. Microscopy and Microanalysis, 30, 712–723, (2024)
  • A. Azócar Guzmán, R. Janisch. Effects of mechanical stress, chemical potential, and coverage on hydrogen solubility during hydrogen-enhanced decohesion of ferritic steel grain boundaries: A first-principles study. Physical Review Materials, 8, 073601, (2024)
  • S. Hamdani, S. Abdeslam, A. Hartmaier et al. Atomistic simulation of the influence of semi-coherent interfaces in the V/Fe bilayer system on plastic deformation during nanoindentation. Modelling and Simulation in Materials Science and Engineering, 32, 045012, (2024)
  • T. Schmalofski, M. Kroll, H. Dette et al. Towards active learning: A stopping criterion for the sequential sampling of grain boundary degrees of freedom. Materialia, 31, 101865, (2023)
  • A. Chauniyal, R. Janisch. How coherent and semi-coherent interfaces govern dislocation nucleation in lamellar TiAl alloys. Advanced Engineering Materials, 25, 2300121, (2023)

All publications

Research Examples

Lamellar size-dependent fracture behavior of gamma-TiAl

The fracture initiation toughness increases with decreasing – maintaining a classical Hall-Petch type relation, which breaks down below a certain limit of around 1.6 nm. Our study indicates that lamellar size is a potential design parameter to tailor TiAl microstructures to achieve enhanced fracture resistance.

Teaser B1
Efficient Prediction of Grain Boundary Energies from Atomistic Simulations via Sequential Design

With the goal of improving data-based materials design, it is shown that by a sequential design of experiment scheme the process of generating and learning from the data can be combined to discover the relevant sections of the parameter space.

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