Evolution of nanocrystallised, highly-reactive multi-layered metal structures

Funded by the National Science Centre, this project looks to understand the complex relationships of the formation of oxide scale clusters and micro-structural features.

Image of multi-layered metals


Research background

The project was funded by National Science Centre (NCN) in Poland to AGH University of Science and Technology.

The development of the next-generation models, which can support the design and control of processing of the nano-crystallised multilayered metallic materials, accounting for various physical phenomena occurring at the highly reactive interfaces and near-surface layers of the multilayered material, was an objective of this project.

A large sample set of different highly reactive nanocrystallised multilayered metal structures undergoing different thermomechanical processes (TMP) over the course of the programme have beeen quantitatively characterised to fully understand the complex relationships between formation of the oxide scale clusters and formation of the microstructural features around the interfaces leading to the corresponding mechanical respond of the bulk multilayered materials.

Research aims

The research aimed to find answers to the following questions.

  • What is the mechanism responsible for the different oxide scale formation at the nanocrystallised interfaces of the multilayered metal structures during thermomechanical processing?
  • Which parameters have an effect and are the most critical for the formation of discontinuous and continuous oxide layers at the interfaces?
  • How the material flow around the formed discontinuous oxide clusters leads to strain localisation and formation of shear bands around the interfaces?
  • How do macroscopic mechanical response of the bulk multilayered material is developed from local responses (rearrangement of dislocations, formation of crystallographic texture, heterogeneous material flow, presence of uncompleted bonding near the oxidised interfaces, etc.)?

How has the research being carried out?

Prediction of physical phenomena, which take place during TMP in different scales at the same time, becomes extremely difficult using traditional FE techniques. The numerical problem became a matter of discrete rather than continuum numerical analysis even assuming today’s level of understanding of physical events at the interface.

Assuming potential inclusion of the scale grain structure and generation of the scale clusters requires implementation of the latest combined discrete/FE methods for linking solid continuum with DE models to simulate multiscale and multiphase phenomena.

The detailed evolution of microstructure gradient around the oxidised interfaces, its control and effect on final product properties, such as mechanical, ductility, toughness, fatigue and damage, especially in the context of the physical features of the materials including SFE, crystallographic structure, chemical composition, etc, have been addressed in this research. The investigation have been aided by the latest computer simulation techniques being able to capture phenomena at various length scales from clusters of grains up to meso level (Crystal Plasticity, Finite Element Method and Digital Material Representation).

It helped to understand the phenomena occurring in such materials and to propose their constitutive description to build a robust computer model for further optimization of their structure/properties/performance ratio.

Research outcomes

More than 20 publications including high IF journals and International Conference Proceedings.