Critical Solidification Experiments for a new Quality of Thermodynamic Key Data

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The proposed project is central in the bundled proposal inasmuch as the data provided form the other projects will be applied in the process for which they have been generated, the liquid/solid phase transformation. In combination with simulation calculations based on the provided data, critical solidification experiments will be designed and carried out that allow for a severe test of the data. The novelty from the point of view of solidification experiments is that instead of using technically relevant alloy compositions and processing conditions, the experimental parameters will be chosen in a way that qualitative differences are to be expected in the solidified microstructure upon a variation of the experimental parameters. Quantitative experimental errors in the microstructural parameters (phase fractions, length scales) determined in the solidified structures generally obscure the reason for deviations between experimental and theoretical results – these errors will interfere less in the present project. Thus, the collectivity of the generated data is verified not in a direct way, but rather by evaluating the consequences for the solidification process. This gives the possibility to further improve the accuracy of particular parameters: the effects of slightly deviant thermochemical or thermophysical data will cumulate during solidification – even if a given value is correct within an acceptable error limit, the cumulation during solidification might show its limitation for being included in the description of the solidification process. This allows for a further improvement of the provided data. A last important point of the project concerns investigations that are characteristic for a quaternary alloy system, i.e. the quantification of the influence of small additions of alloying elements or impurities. The third and/or fourth alloying element can be used as impurity in simulation and experiment. It is expected that insight will be gained about the limit from which impurities need to be considered as additional alloying element.