Heterogeneous nucleation and microstructure formation in peritectic alloy systems

包晶合金体系中的异质成核和微观结构形成

• 批准号: 51053136
• 负责人: Professorin Dr.-Ing. Heike Emmerich
• 金额: --
• 依托单位: Institut für Metallurgie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/51053136?language=en
• 关键词: Heterogeneous; nucleation; microstructure; formation; peritectic

The global goal - set in the initial proposal for the entire funding period - remains the systematic research aiming at the understanding of heterogeneous nucleation and microstructure formation during peritectic solidification of alloys comprising all stages. This work will be systematically continued, while also being inspired by the results of other groups within the SPP. Furthermore, the focus of the project will shift in the next two years, bridging the scale difference between microstructure evolution and nucleation.The specific goals for the second funding period can be summarized as: (i) the generation and utilization of high precision thermodynamic and constitutional data to build refined and consistent thermodynamic descriptions; (ii) further development of the phase-field model and generation of simulated microstructures; (iii) microstructure analysis of directionally solidified samples; (iv) closer coupling of advanced calorimetric and phase-field investigations for a deeper understanding of the role of each of the four stages of peritectic solidification; and (v) clarify the interplay between the four stages on the type of peritectic reaction and the external solidification parameters (temperature gradient G and solidification rate v). Work on the Al-Ni system will be advanced since this is an excellent model system for investigating peritectics of type III and type II. As additional and independent material system Al-Cu has been chosen to investigate type II and type I peritectics. The choice of both alloy systems will, moreover, strengthen the existing network by exchange of important data with colleagues in the SPP.For this work we recognize that the nature of peritectic solidification makes it impossible to directly measure most kinetic properties of the reaction. We believe that by meticulously investigating peritectic solidification down the scale ladder from final microstructure over growth and its three different stages, and by coupling experimentation with simulation, the gap to heterogeneous nucleation can be bridged. By reducing the degrees of freedom for the choice of parameters in the phase-field simulation, the uncertainty range for the parameters of nucleation can be closed. Also, closer coupling of the phase-field model with experimental results makes it possible to jointly analyze a broad range of experimental techniques. Results, which would otherwise not be comparable, can be fed into a unifying phase-field model that is capable of describing all solidification conditions. This is the strength and beauty of this cooperation between our groups in Aachen and Clausthal in this joint project.

初步提案中为整个供资期设定的总体目标仍然是系统研究，目的是了解合金在包晶凝固过程中包括所有阶段的异质形核和微观结构的形成。这项工作将系统地继续下去，同时也将受到最高人民检察院其他小组成果的启发。此外，该项目的重点将在未来两年转移，弥合微观结构演变和成核之间的尺度差异。第二个资助期的具体目标可以概括为：（i）生成和利用高精度的热力学和组成数据，以建立精确和一致的热力学描述;（ii）进一步发展相场模型并生成模拟微观结构;（iii）定向凝固样品的微观结构分析; ㈣将先进的量热法和相场研究更密切地结合起来，以便更深入地了解周向凝固四个阶段中每一阶段的作用;（v）阐明了这四个阶段对周晶反应类型和外部凝固参数（温度梯度G和凝固速率v）的相互影响。Al-Ni系是研究第三型和第二型包壳构造的一个很好的模型系统，因此将进一步开展这方面的工作。作为附加的和独立的材料系统，Al-Cu被选择来研究II型和I型包结。此外，这两种合金系统的选择将通过与SPP的同事交换重要数据来加强现有的网络。对于这项工作，我们认识到，周晶凝固的性质使得不可能直接测量反应的大多数动力学性质。我们相信，通过细致地研究从最终微观结构到生长的尺度阶梯及其三个不同阶段的周晶凝固，并通过将实验与模拟相结合，可以弥合异质形核的差距。通过减少相场模拟中参数选择的自由度，可以关闭成核参数的不确定性范围。此外，相场模型与实验结果的更紧密耦合使得可以联合分析广泛的实验技术。结果，这将是不可比的，可以被送入一个统一的相场模型，能够描述所有的凝固条件。这就是我们在亚琛和克劳斯塔尔的团队在这个联合项目中合作的力量和魅力。