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轴承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了解。这是特别感兴趣的应用程序的扩散测时岩浆系统，其中涉及晶体的生长和溶解和相关的晶体形状的变化导致修改的扩散配置文件的纹理成熟的过程。相场建模方法，这是一个有效的，一致的工具，模拟复杂的扩散和生长现象，将被使用。一个有效的多组分多相场方法将耦合到各向异性扩散和各向异性刻面晶体生长的方法。一个模型橄榄石熔体系统已被选定为这一初步研究。基于表面能和热力学参数的估计值的纹理演变将进行研究，并与实验结果进行比较。该研究项目的一个特定目标是调查晶体生长/溶解对岩浆环境中特定晶体寿命的结构和晶体形状演变的影响。所开发的方法将有助于定义扩散计时法访问的时间尺度的上限。生长/溶解过程的各向异性多组分相场建模也为相关材料系统中微观结构和织构演化的可靠预测提供了基础。

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.