Outstanding Reviewer 2022
Again: Prof. Gerhard Wilde were honoured as outstanding reviewers 2022 for the journal Acta Materialia.
Degrees in winter semsester 2022/2023
Dr. Katharina Spangenberg (AG Wilde),
Dr. Sandipan Sen (AG Wilde),
Dr. Jan Prüßing (AG Bracht) and
Dr. Jingfeng Zhang (AG Wilde)
finished their doctorate! Congratulation!
Graeme Murch Award
During the recent DSL (Diffusion in Solids and Liquids) Conference hold in Florence, Italy, June 2022, Dr. Esakkiraja Neelamegan (currently post-doc by Apl.-Prof. Dr. S. Divinski) has received a prestigious Graeme Murch Award. The Graeme Murch Award was for the first time granted in the 19-year history of the DSL Conferences and it is the highest distinction given by the DSL conference organizers. This award recognizes the contributions of early career scientists (up to 5 years of research experience following Ph. D.) within the wider field of diffusion research.
Dr. Esakkiraja conducted his PhD study at the Department of Materials Engineering, Indian Institute of Science, Bangalore, India in the research group of Prof. Dr. Aloke Paul (who was a former AvH Fellow at our Institute and worked with Apl.-Prof. Dr. S. Divinski). Dr. Esakkiraja contributed largely to the development of novel pseudo-binary and pseudo-ternary couple methods which have broken the paradigm of interdiffusion in multi-component alloys with the number of components larger than three. He performed a series of fundamental experiments which for the first time provided an access to the quantitative determination of the (pseudo-binary) interdiffusion coefficients in multi-component alloys. Even intrinsic diffusion coefficients were convincingly shown to be accessible via these novel approaches, together with systematic accounting for the vacancy wind factors.
The current research work of Dr. Esakkiraja is directed to the combination of the two fundamental techniques of diffusion studies in the multi-component alloys, i.e. the (radio)tracer and interdiffusion couple methods, in different systems including multi-principal element alloys.
We congratulate Dr. Esakkiraja Neelamegan with this prestigious Award and wish further successes in his carrier!
Double Strike !
Dr. Mohan Muralikrishna Garlapati, Postdoc in AG Wilde, has obtained two exceptional awards: he has received the 2021 „Best Thesis“ award of IIT Madras at Chennai in India for his work on high entropy alloys. Mohan performed a part of his thesis work at our institute, working closely together with Apl.-Prof. Sergiy Divinski. Mohan performed the main part of his thesis work at IIT Madras in the group of Prof. B.S. Murty with whom our group closely collaborates. The thesis award of IIT Madras is a highly prestigious price, since IIT Madras is the top elite institution in the area of materials science and metallurgy in India, making the competition for that award truly fierce. We are very happy that Mohan was selected as awardee this year and we feel that with Mohan, the award has been given to the right person.
Almost at the same time, Mohan has been awarded with a research fellowship of the Alexander von Humboldt foundation for 24 months. This fellowship for young scientists from abroad is not only highly prestigious, but also highly competitive. It allows Mohan to work independently on the scientific project that he defined for the application. We are lucky and very happy to have Mohan in our group for the completion of his fellowship project on High Entropy Oxides that will be undertaken in close collaboration with Prof. Horst Hahn from KIT in Karlsruhe, who acts as Co-host of Mohan’s fellowship.
We congratulate Mohan for his great success and we are looking forward to continue working with him.
Watching Atoms Jump
In a paper just published in the reputed journal Advanced Functional Materials, scientists from the Wilde group were able to directly observe and quantitatively measure for the first time the local dynamics of atomic rearrangements at room temperature in an amorphous solid [K. Spangenberg et al.,"Direct View on Non-Equilibrium Heterogeneous Dynamics in Glassy Nanorods", Adv. Funct. Mater. 2021, 31, 2103742; DOI: 10.1002/adfm.202103742]. Such rearrangement processes in glasses contribute significantly to their wide range of applications since they represent the elementary process for the possibility to set material properties. Thereby, the non-crystalline structure of glasses allows property changes (e.g. packing density) which are not possible in the presence of a crystal lattice. To date, however, large gaps exist in understanding the underlying atomic mechanisms of this so-called ‘structural relaxation’. A novel method, which is based on the application of transmission electron microscopy, promises a completely new and direct access.
For this purpose, time series of dark-field images are recorded for application of the so-called electron correlation microscopy. The subsequent analysis of these time series includes calculating the temporal correlation of intensities in the dark-field images.
The resulting decays are fitted by a stretched exponential function (taking into account an ensemble of different activation energies), leading to characteristic fitting parameters - as such, the decay time τ. By analyzing each pixel in the micrograph time series, the material’s typical time and length scales are locally resolved and their spatial distribution is presented in τ(x,y)-maps.
In this research work, which was funded by the German Research Foundation, the dynamics of atomic rearrangement in metallic glass nanowires made of FeNiP are investigated. This fascinating class of material offers ideal prerequisites as a model system for disordered systems. By means of electron correlation microscopy, timescales of the heterogenous dynamics of a glassy FeNiP alloy are locally resolved, revealing a decoupling into two different processes at room temperature. Besides the first quantitative and direct observation of local rearrangements and their characteristic timescale at temperature well below the glass transition, this is an important result for expanding our knowledge of the complex dynamics in materials with disordered atomic structure. An in-depth understanding of these processes and mechanisms opens innovative possibilities for property design of glasses adapted to their respective application.
Best Poster Award
Unsere Promovendin Shabnahm Taheriniya hat im August 2021 auf der internationalen Mikroskopie-Konferenz (MC 2021) den Posterpreis mit dem Poster-Titel „Structural resolution of severely deformed dual-phase high entropy alloys using nano-beam diffraction patterns in transmission electron microscopy“ erhalten.
Wir gratulieren ihr herzlich!