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Metal alloy solidification in thin capillaries - a study of the solid-liquid interfacial energy anisotropy using a novel approach

薄毛细管中的金属合金凝固——利用新方法研究固液界面能量各向异性

基本信息

批准号：
274832340
负责人：
Professor Dr. Markus Rettenmayr (†)
金额：
--
依托单位：
Lehrstuhl für Metallische Werkstoffe
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/274832340?language=en
关键词：
Metal alloy solidification thin capillaries

项目摘要

The anisotropy of the interfacial energy of the solid-liquid phase boundary is central with respect to various aspects of metal solidification processes and exerts a crucial influence on the solidified microstructure. The experimental separation of the anisotropy effects from other causes, e.g., morphology changes through melt convection is, however, extremely challenging. Existing methods for the measurement of the anisotropy parameters require considerable experimental effort and lead to substantial scatter of measured values.The present project aims to study the solidification of metallic alloys in thin capillaries with diameters in the order of magnitude of 1µm. Experiments with metal alloys previously documented in the literature did not achieve diameters below 200µm. In the capillaries used in the present project convection effects are suppressed down to the minimum experimental attainable amount which allows the investigation of the shape of the solid-liquid interface quasi free of fluctuations. The interface is crated in a setup for directional solidification with parameters chosen to force morphological instability. By decorating the interface with a secondary phase during quenching its shape remains observable post mortem by scanning electron microscopy. Combining focused ion beam tomography and electron backscatter diffraction, the three dimensional interface shape will be investigated in dependence of its crystallographic growth orientation.Numerical investigations will be conducted using our recently developed "Meshless Front Tracking" (MFT) method for the simulation of phase transformations, which will be extended to the conditions of the solidification in capillaries. In contrast to the established simulation methods, the MFT method is free of any anisotropic influence of the spatial discretization on the simulation results, which renders it especially suited for the examination of anisotropy effects. With this method the influence of both the interfacial energy anisotropy and the crystallographic growth orientation will be numerically investigated. Furthermore, by combining experiments and simulation the anisotropy parameters can be determined. The present project is therefore both a proof of concept for a novel measuring method and a study of the influence of the solid-liquid interfacial energy anisotropy on solidification.

固-液相界面能的各向异性是金属凝固过程各个方面的核心，并对凝固组织产生至关重要的影响。各向异性效应与其他原因的实验分离，例如，然而，通过熔体对流的形态变化是极具挑战性的。现有的测量各向异性参数的方法需要大量的实验工作，并导致大量的测量值分散。本项目旨在研究金属合金在直径为1µm数量级的薄毛细管中的凝固。以前文献中记载的金属合金实验没有达到200µm以下的直径。在本项目中使用的毛细管中，对流效应被抑制到实验可达到的最小量，这允许研究准自由波动的固液界面的形状。该接口是crated在设置定向凝固的参数选择，迫使形态不稳定。通过在淬火过程中用第二相装饰界面，其形状在死后通过扫描电子显微镜保持可观察。结合聚焦离子束层析技术和电子背散射衍射技术，研究了三维界面形状与晶体生长取向的关系，并将“无网格前沿跟踪”（Meshless Front Tracking，MFT）方法推广到毛细管凝固条件下进行了数值模拟。与现有的模拟方法相比，MFT方法不受空间离散化对模拟结果的任何各向异性影响，这使得它特别适合于检查各向异性效应。用这种方法的界面能各向异性和晶体生长取向的影响将进行数值研究。此外，通过实验和模拟相结合，可以确定各向异性参数。因此，本项目是一种新的测量方法和固液界面能各向异性对凝固的影响的研究的概念证明。