Scope

Scope

The ADIS2016 workshop is number six in a series of international scientific seminars on the topic “Ab initio Description of Iron and Steels (ADIS)” which started in 2006. The aim of this series is to create a platform for leading experts in ab initio metals research to discuss and exchange recent results and scientific developments. Such a forum is needed because the complexity of realistic iron-based materials with respect to chemical, magnetic and microstructure is a challenge for every ab initio approach, presenting no single well-paved road for simulations. Instead – to have success – a wide array of approaches and algorithms needs to be developed, implemented and evaluated with respect to predictive power. This challenge, which is well appreciated in the materials science community, can only be tackled in a combined multi-disciplinary effort.

To best fit these needs, the ADIS workshops are characterized by Gordon style, tutorial-like one hour talks, intensive discussions and, last but not least, the inspiring cooperationpromoting atmosphere of Ringberg castle. Although the ab initio description of iron and steel remains the main goal, each of these events has its own focus on a specific topic: The series started 2006 on “Status and future challenges”. The focus of following workshops was for example on “Thermodynamics and Kinetics” or “Magnetism”, but also “Mechanical properties” have been a topic before. All of them were mainly devoted to the discussion of recently developed ab initio based methods, which allow one to answer key questions in the respective field. To ensure the multidisciplinary approach, selected presentations that report about alternative methods or experimental investigations are also desired.

Scientific Content

The ADIS2016 workshop has the major topic "Ab initio description of Iron and Steel". Its focus on “Mechanical properties” addresses aspects and communities that have not been considered in the last couple of ADIS meetings. The modelling and simulation of mechanical properties is highly relevant and challenging, since the mechanical response is characterized by a complex interplay of bulk properties (such as atomic configuration, binding energies, elastic properties) and the microstructure (e.g., grain boundaries, dislocations, precipitates). This necessitates the development of novel simulation strategies and the combination of various physical concepts.

More specifically the present seminar will be used, to present and to discuss latest developments in the following fields:

1. Precipitate formation: This includes questions like nucleation mechanisms, the partitioning of elements between the matrix and a precipitate phase, as well as timetemperature-transformation (TTT) diagrams. Further, contributions on the role of Interfaces, the degree of coherency and elastic properties are welcome.

   Methods: The majority of contributions should be on ab initio calculations, but kinetic Monte-Carlo simulations, connections to continuum mechanics and Calphad simulations etc. should also be discussed. Experimental input (e.g. using APT, HRTEM, …) is desired.

2. Dislocations: The spectrum of considered aspects ranges from the description of their structure, via the interaction with defects (e.g. impurities, vacancies) up to understanding the mechanisms of hardening.

   Methods: Methods to overcome the challenge of an ab initio based description of these line defects (e.g. lattice Green’s functions approaches) will be the focus, while more approximate methods such as molecular dynamics simulations based on tight binding and bond-order potentials will also be discussed.

3. Failure mechanisms: The processes yielding crack initiation and propagation will be discussed. Aspects like the structure of crack tips, decohesion, mechanisms for hydrogen embrittlement will also be considered.

   Methods: The focus will be on insights obtained from ab initio based approaches. Selected results from MD simulations and experiments are also welcome.

4. Planar defects: The energy of stacking faults is decisive for deformation and twinning mechanisms. The dependence on chemical composition, local strain, anc temperature, as well as segregation effects are possible topics to be presented.

   Methods: A majority of contribution with a connection to ab initio approaches is desired, but methods operating on larger scales are also appreciated.