Critical Solidification Experiments for a new Quality of Thermodynamic Key Data

拟议项目是捆绑式提案的核心，因为其他项目提供的数据将应用于产生这些数据的过程，即液相/固相转化。结合基于所提供数据的模拟计算，将设计并进行临界凝固实验，以便对数据进行严格的测试。从凝固实验的观点来看，新颖性在于，代替使用技术上相关的合金成分和加工条件，实验参数将以这样的方式选择，即在实验参数变化时，预期在凝固的微观结构中存在质的差异。在凝固结构中确定的微观结构参数（相分数，长度尺度）的定量实验误差通常掩盖了实验结果和理论结果之间偏差的原因-这些误差在本项目中的干扰较小。因此，所生成的数据的总体性不是以直接的方式进行验证，而是通过评估固化过程的后果来进行验证。这使得进一步提高特定参数的准确性成为可能：略微偏离的热化学或热物理数据的影响将在固化期间累积-即使给定值在可接受的误差限度内是正确的，固化期间的累积也可能显示出其局限性，无法包括在固化过程的描述中。这允许进一步改进所提供的数据。该项目的最后一个重点涉及四元合金系统的特征研究，即量化少量添加的合金元素或杂质的影响。第三和/或第四合金元素可用作模拟和实验中的杂质。预计将获得有关杂质需要被视为额外合金元素的限度的见解。

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.