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Design of Phase Transition Kinetics in Non-Equilibrium Metals

Periodic Reporting for period 4 - TRANSDESIGN (Design of Phase Transition Kinetics in Non-Equilibrium Metals)

Reporting period: 2022-08-01 to 2023-06-30

The first technological use of non-equilibrium phase transitions in metals for designing properties of materials is documented as ~800 BC. Nearly all classes of materials show non-equilibrium phase transitions. Understanding how fast these transitions occur is a key question in materials science and the processing of materials. In metals, kinetics is connected to diffusion via atomic lattice vacancies. However, there was no universal sound and predictive physical understanding of the kinetics under non-equilibrium situations so far, because theory cannot be verified experimentally. The in situ measuring of non-equilibrium kinetics and the corresponding vacancy evolution was not accessible at industrially relevant and controlled high thermal rates. The development of unique strategies for in situ measuring of non-equilibrium phase transition kinetics and the microscopic observation of the underlying processes were the objectives of TRANSDESIGN.
The project closed longstanding experimental-theoretical gaps with significant impact on the optimization and design of new kinetically driven processes and products in the field of metallurgy. Bridging chip calorimetry and atomic characterization experiments with thermo-kinetic and atomistic simulations were successfully used to validate existing theoretical models and to create new universal guidelines to understand and to design phase transition kinetics in non-equilibrium metallic systems. The fundamentals gained within the TRANSDESIGN project are universal to significantly contribute to the advancement of the European competence in materials science. In particular, in addition to improving the understanding and the improved measurement of non-equilibrium phase transformations, the TRANSDESIGN project has also already succeeded in application of these fundamentals. For example, new materials that can withstand the extreme conditions in space have been designed. The key for this was to be able to precisely control the movement of non-equilibrium vacancies to prevent damage to the material by high-energy particles in space, deduced from the basic design developed within TRANSDESIGN.
We have accomplished our goal of utilising chip calorimetry for non-equilibrium phase transitions in relevant metals (1,2). The gained methodical results in the field of advanced chip calorimetry have been published and satisfy our expectation on the indented high-performance high-rate calorimetry. Our methodology was already applied on in situ measurements of non-equilibrium phase transitions in different alloys (e.g. Al alloys for additive manufacturing). Our work on measuring non-equilibrium vacancy evolution at high rates and the required increased sensitivity led to unexpected results, such as the possibility to precisely measure the specific heat capacity of small scaled samples at rapid rates.
The progress in microscopic observations of non-equilibrium phase transitions within TRANSDESIGN has already triggered the new field of “Nanometallurgy” and we made vast improvement in the in situ observation of phase transitions via electron microscopy (3,4). Transitions in metals studied range from the melting, solidification, sublimation, precipitation, diffusion and alloying to the effect of very high non-equilibrium concentrations caused by ion or electron bombardment. The observation of vacancy marker atoms was possible. In general, we have made fundamental progress in the understanding of non-equilibrium vacancy behavior within TRANSDESIGN (5). Especially our in situ electron microscopy studies on high non-equilibrium concentrations caused by ion or electron bombardment and their effects in different materials led to an unexpected fast fulfilment of the future goal to design phase transition kinetics in non-equilibrium metallic systems with the help of TRANSDESIGN. A new material derived from this (6) that can withstand the extreme conditions in space has attracted a lot of international attention. Our most recent work on this topic has not yet gone through the full peer review process, but already the pre-print on it has triggered worldwide media interest (e.g. an interview of the PI at the end of the project in 2023 with the British magazine "New Scientist"). At the time of the final report, 24 peer-reviewed articles had already been published in leading journals and several more are in the process of publication.

Example references:
1. Quick, C. R., Schawe, J. E. K., Uggowitzer, P. J. & Pogatscher, S. Measurement of specific heat capacity via fast scanning calorimetry—Accuracy and loss corrections. Thermochim Acta 677, (2019).
2. Quick, C. R., Dumitraschkewitz, P., Schawe, J. E. K. & Pogatscher, S. Fast differential scanning calorimetry to mimic additive manufacturing processing: specific heat capacity analysis of aluminium alloys. J Therm Anal Calorim 148, (2023).
3. Coradini, D. S. R. et al. In situ transmission electron microscopy as a toolbox for the emerging science of nanometallurgy. Lab Chip (2023).
4. Dumitraschkewitz, P. et al. MEMS-Based in situ electron-microscopy investigation of rapid solidification and heat treatment on eutectic Al-Cu. Acta Mater 239, 118225 (2022).
5. Dumitraschkewitz, P., Uggowitzer, P. J., Gerstl, S. S. A., Löffler, J. F. & Pogatscher, S. Size-dependent diffusion controls natural aging in aluminium alloys. Nat Commun (2019).
6. Tunes, M. A., Stemper, L., Greaves, G., Uggowitzer, P. J. & Pogatscher, S. Prototypic Lightweight Alloy Design for Stellar-Radiation Environments. Advanced Science 7, (2020).
We have definitely made progress that goes beyond the state of the art and also beyond the expected results of the TRANSDESIGN project. Chip calorimetry was established for relevant metals. A method to significantly improve the sensitivity was also presented in this study. Moreover, it was shown that, in addition to non-equilibrium vacancy kinetics, a highly precise measurement of the specific heat capacity in high-speed processes is also possible.
In the field of microscopic observation of non-equilibrium phase transitions, the opened field of "nanometallurgy" represents a significant improvement in the in-situ observation of rapid phase transitions using electron microscopy. However, the non-equilibrium diffusion effect found is a breakthrough, especially for the microscopic observation of such processes, as it was not considered in the past. This is of particular importance when studying non-equilibrium diffusion reactions in metals, as it means that the conventional generation of a significant number of thermal vacancies by quenching is not possible. In general, we have made fundamental progress in the understanding of non-equilibrium vacancy behavior within TRANSDESIGN. The unexpectedly rapid fulfilment of the goal of designing the kinetics of phase transitions in metallic non-equilibrium systems is one result of this, and the development of a new material that can withstand extreme non-equilibrium conditions in space is a real and unexpected breakthrough (see interview of the PI with the British magazine "New Scientist": https://www.newscientist.com/article/2343246-aluminium-alloy-could-boost-spacecraft-radiation-shielding-100-fold/).
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