Application of phase-field simulation of solidification and texture evolution to diffusion chronometry

该项目的目的是开始对熔体承载系统中晶体生长和溶解过程中的生长机制和织构形成进行定量理解。这对于岩浆系统中扩散计时法的应用是特别有趣的，在岩浆系统中，涉及晶体生长和溶解的结构成熟过程以及晶体形状的相关变化导致扩散剖面的修改。相场建模方法，这是一个有效的，热力学一致的工具，模拟复杂的扩散和生长现象，将使用。一种有效的多组分多相场方法将与各向异性扩散和各向异性面晶体生长方法相结合。选择了一个橄榄石-熔体模型体系进行初步研究。基于表面能和热力学参数的估价值的织构演化将被研究，并与实验结果进行比较。该研究项目的一个特定目标是研究在岩浆环境中，晶体生长/溶解对特定晶体寿命的影响。所开发的方法将有助于确定扩散计时法可达到的时间尺度的上限。生长/溶解过程的各向异性多组分相场模型也为相关材料体系的微观结构和织构演化提供了可靠的预测基础。

The aim of the project is to initiate a quantitative understanding of the growth mechanisms and texture formation during the growth and dissolution of crystals in melt bearing systems. This is of particular interest for the applications of Diffusion Chronometry to magmatic systems, where the process of textural maturation involving growth and dissolution of crystals and associated changes in crystal shapes lead to modification of diffusion profiles. The phase-field modeling method, which is an efficient, thermodynamically consistent tool for modeling complex diffusion and growth phenomena, will be used. An effective multicomponent multi-phase-field approach will be coupled to the methods for anisotropic diffusion and anisotropic faceted crystal growth. A model olivine-melt system has been chosen for this preliminary study. Textural evolutions based on estimated values of surface energy and thermodynamic parameters will be studied and compared to results from experiments. A particular goal of the research project is the investigation of the effect of texture and crystal shape evolution by crystal growth/dissolution on the lifetime of a particular crystal in a magmatic environment. The developed approach will help to define the upper limits of timescales accessible by diffusion chronometry. Anisotropic multicomponent phase-field modeling of growth/dissolution processes also provides a foundation for reliable predictions of microstructure and texture evolution in related material systems.