Latest News


New place, new position and a new beginning

posted Jul 11, 2018, 6:08 AM by Arun Prakash   [ updated Jul 11, 2018, 6:22 AM ]


I am happy to announce that I have recently shifted to Freiberg, Germany, to start my new job at the Technical University Bergakademie Freiberg (TUBAF). I will be working as a senior scientist in the Micromechanical Materials Modelling (MiMM) group of Prof. Sandfeld.

Although I will continue to work on Atomistic Simulations, Crystal Plasticity and Multiscale Modeling, I aim to also move towards Data science and analytics. I am looking forward to fruitful collaboration with my new work colleagues. 

Many thanks to all my former colleagues at the Institute I, Department of Materials Science and Engineering, particularly the Simgroup of Prof. Bitzek, in Erlangen. It was a wonderful 6 years at Erlangen.

In the spirit of changes in the career pathway, the site has also attained a new design.

Poster Award at the International CAE conference

posted Nov 19, 2017, 10:32 AM by Arun Prakash

Happy to announce that our poster titled "A Multiscale Simulation Framework of the Accumulative Roll Bonding Process Accounting For Texture Evolution" has won the "Best Poster" award at the 33rd International CAE conference (http://caeconference.com). The conference had the theme "Simulation: The Soul of Industry 4.0" and was held in Vicenza, Italy.

Many thanks to the organizers (#Enginsoft) for inviting me to present our results at this excellent conference. Congrats also to the other winners of the award. It is really nice to see the high quality and wide variety of work that has been presented.

New paper on the role of GB structure and topology in atomistic simulations published

posted Jul 7, 2017, 1:23 AM by Arun Prakash

Our new paper entitled "Influence of grain boundary structure and topology on the deformation behaviour of nanocrystalline aluminum as studied by atomistic simulations" has been published in the Journal "International Journal of Plasticity". The paper investigates the role of realistic GB topology and network -- obtained from mesoscale grain growth simulations -- on the deformation behaviour of nanocrystalline aluminum. In particular, we look into dislocation activity and the details of deformation mechanisms that are activated due to the presence of curvature in GBs.

Abstract: Nanocrystalline materials, with grain sizes below 100 nm, have been the subject of many research studies in the recent past. At these reduced grain sizes, grain boundaries (GBs) play a very important role in the deformation of such materials. Large scale atomistic simulations that are often used to illuminate the deformation mechanisms in such materials must accurately account for the topology, structure and network of GBs. In this work, we perform atomistic simulations on nanocrystalline aluminum under tensile loading, using a structure with a relaxed GB network obtained from three-dimensional grain growth simulations, and compare the results to that obtained from structures generated using the Voronoi tessellation method. The results show that the grain growth sample results in consistently higher macroscopic stresses when compared to the Voronoi tessellated microstructures. The latter, additionally, tend to overestimate GB deformation, whilst simultaneously underestimating the deformation due to dislocation slip. More importantly, twinning is observed in multiple grains in the grain growth sample, in contrast to the near absence in Voronoi tessellated microstructures. The results are carefully discussed in terms of sample characteristics, stacking fault energies, and GB structure and network.

New Paper on Atomistic simulation of FIB machining of strain Si

posted May 3, 2017, 1:42 AM by Arun Prakash   [ updated May 3, 2017, 1:50 AM ]

Our new paper on "Atomistic simulations of focused ion beam machining of strained silicon" has now been published. Please click here to access the article.

Abstract: The focused ion beam (FIB) technique has established itself as an indispensable tool in the material science community, both to analyze samples and to prepare specimens by FIB milling. In combination with digital image correlation (DIC), FIB milling can, furthermore, be used to evaluate intrinsic stresses by monitoring the strain release during milling. The irradiation damage introduced by such milling, however, results in a change in the stress/strain state and elastic properties of the material; changes in the strain state in turn affect the bonding strength, and are hence expected to implicitly influence irradiation damage formation and sputtering. To elucidate this complex interplay between strain, irradiation damage and sputtering, we perform TRIM calculations and molecular dynamics simulations on silicon irradiated by Ga+ ions, with slab and trench-like geometries, whilst simultaneously applying uniaxial tensile and compressive strains up to 4%. In addition we calculate the threshold displacement energy (TDE) and the surface binding energy (SBE) for various strain states. The sputter rate and amount of damage produced in the MD simulations show a clear influence of the strain state. The SBE shows no significant dependence on strain, but is strongly affected by surface reconstructions. The TDE shows a clear strain-dependence, which, however, cannot explain the influence of strain on the extent of the induced irradiation damage or the sputter rate.

New paper - Realistic vs. Idealized Microstructures

posted Jan 28, 2017, 1:40 PM by Arun Prakash   [ updated Feb 2, 2017, 6:30 AM ]

Our new paper entitled "Idealized vs. Realistic Microstructures: An atomistic simulation case study on γ/γ′ Microstructures" has now been published in the open-access journal Materials. To access the paper please click here

Abstract: Single-crystal Ni-base superalloys, consisting of a two-phase γ/ γ ′ microstructure, retain high strengths at elevated temperatures and are key materials for high temperature applications, like, e.g., turbine blades of aircraft engines. The lattice misfit between the γ and γ ′  phases results in internal stresses, which significantly influence the deformation and creep behavior of the material. Large-scale atomistic simulations that are often used to enhance our understanding of the deformation mechanisms in such materials must accurately account for such misfit stresses. In this work, we compare the internal stresses in both idealized and experimentally-informed, i.e., more realistic, γ/ γ′ microstructures. The idealized samples are generated by assuming, as is frequently done, a periodic arrangement of cube-shaped γ′ particles with planar γ/ γ ' interfaces. The experimentally-informed samples are generated from two different sources to produce three different samples—the scanning electron microscopy micrograph-informed quasi-2D atomistic sample and atom probe tomography-informed stoichiometric and non-stoichiometric atomistic samples. Additionally, we compare the stress state of an idealized embedded cube microstructure with finite element simulations incorporating 3D periodic boundary conditions. Subsequently, we study the influence of the resulting stress state on the evolution of dislocation loops in the different samples. The results show that the stresses in the atomistic and finite element simulations are almost identical. Furthermore, quasi-2D boundary conditions lead to a significantly different stress state and, consequently, different evolution of the dislocation loop, when compared to samples with fully 3D boundary conditions

Positive evaluation of Computational Nanoscience course

posted Oct 2, 2016, 8:10 AM by Arun Prakash   [ updated May 3, 2017, 2:21 AM ]

One of my regular courses/exercises has been evaluated extremely positively by students. The course is offered together with Prof. Erik Bitzek. The course is titled "Exercises for Computation Nanoscience" (dt. Übung zu Computational Nanoscience). The course is offered as a block lecture held over 2 complete days and as an exercise to the course "Computational Nanoscience". 

The course is held in German.

Our course was evaluated with a grade of 1.32 and has landed the top 5 position (of 60). 

Source: http://www.tf.fau.de/studium/evaluation/ss16/ss16_u.html#ÜP5 --> Look for the section ÜP5 •  Kategorie der Übungen  •  Pflichtfach (kein GOP-Fach)  •  5…19 Rückläufer

Successful completion of the 1st Erlangen school on Atom Probe Tomography

posted Oct 2, 2016, 7:55 AM by Arun Prakash

The 1st Erlangen school on Atom Probe Tomography came to a successful completion on the 15th of Sep. Close to 40 participants from various european countries were present at the workshop. The workshop included talks from Dr. Baptiste Gault, MPIE, Düsseldorf, Prof. Peter Felfer, FAU and me. Additionally, hands-on tutorials, including FIB lift-out were a part of the workshop. A overwhelmingly positive feedback was given by the participants of the workshop. 

If you are interested in more details of the workshop, please feel free to visit the course webpage: http://www.eam.fau.de/aptschool  

APT Workshop in Erlangen

posted Sep 11, 2016, 9:14 AM by Arun Prakash

The first Atom Probe Tomography workshop will be held from 12-Sep to 15-Sep. The Workshop is being jointly organized by Prof. Peter Feller and myself. The goal of this school is to teach the participants the basics of atom probe tomography, with a strong practical aspect, to foster independent use. This will include reconstruction, data interpretation and treatment and full day FIB sample preparation practicals on site. We have had excellent interest thus far with more than 30 participants.

For details, pls. see the attached flyer and summer school webpage http://www.eam.fau.de/aptschool

Looking forward to welcoming the participants in Erlangen.

Back from two excellent conferences

posted Sep 11, 2016, 9:09 AM by Arun Prakash

Just back from two excellent conferences in the past two weeks - the fifth CMCn conference in Düsseldorf, and the the 15th EMMC in Brussels. Excellent contributions in both conferences on a variety of topics. I personally had a fantastic time interacting and discussing with other scientists. At the EMMC, I also met some former members of our group - Wolfram Georg Nöhring and Jonathan Amodeo. 

Yours truly also presented some latest research on notched and untouched free standing thin films and films on a substrate. My talk was entitled "Deformation behavior of nanocrystalline thin films as studied by atomistic simulations".


FAU Erlangen Nürnberg among the top 10 innovative universities in Europe

posted Jun 23, 2016, 7:29 AM by Arun Prakash   [ updated Jun 23, 2016, 7:30 AM ]

Some excellent news! The Friedrich-Alexander-Universität Erlangen-Nürnberg has been ranked 6th in the inaugural Reuters Top 100: Europe’s Most Innovative Universities ranking. Check it out!

Links:
https://www.timeshighereducation.com/features/100-most-innovative-universities-europe-2016
http://www.reuters.com/article/us-innovative-stories-europe-idUSKCN0Z00CT

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