Development of microstructural solidification simulation code for light alloys

轻合金显微组织凝固模拟程序开发

• 批准号: RGPIN-2014-06561
• 负责人: Jung, InHo
• 金额: $ 1.48万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=638238
• 关键词: Development; microstructural; solidification; simulation; code

The ultimate goal of the candidate’s research is the development of virtual simulation tools for high temperature industrial metallurgical processes based on thermodynamic databases and kinetic models. In order to achieve this goal, the previous Discovery Grant (DG) focused on the development of thermodynamic database for pyrometallurgy and alloys. Many thermodynamic databases have been developed as the results of DG and also other research grants over the last five years. In this DG, the candidate would like to develop a kinetic solidification model to utilize such thermodynamic database for real casting process. Most of light alloy products are produced through the casting process. Therefore, the as-cast microstructure is one of the determining factors that control the mechanical properties. However, the evolution of as-cast microstructures with casting parameters is still not well investigated. In the casting industry, computational fluid dynamics and heat flux simulations performed by commercial software packages like FLUENT and MAGMA are mostly used to understand the filling behavior in very complex casting molds. Unfortunately, such software cannot provide accurate microstructural information about the casting conditions. On the other hand, phase field modeling was pursued to simulate the development of as-cast microstructures in 2-D and 3-D views, but the calculation is too slow to be directly applied to the practical casting simulation of multicomponent alloys. So, a simple but practical kinetic microstructure simulation model is needed for computational materials design in casting. In the present research program, a versatile 1-D microstructural solidification model with a user interface will be developed to cover a wide range of commercial Mg and Al alloys under a wide range of casting conditions. No such dedicated solidification simulation tool is currently available for Mg and Al alloys. In the past years, the candidate’s research group has carried out fundamental and comprehensive casting experiments to understand the evolution of the as-cast microstructure of Mg-Al-Zn alloys and Mg single crystal diffusion couple experiments to measure the diffusivity in Mg-Al and Mg-Zn systems. All key solidification theories to explain the microstructure development during solidification will be taken into account in the 1-D microstructural solidification model. Moreover, the thermodynamic database, which can calculate solidus, liquidus and equilibrium secondary phases, will be dynamically linked to the kinetic solidification model. This solidification model will calculate, within a short time (less than 10 min), all the important solidification microstructural features such as the primary and secondary dendrite spacing, the solute segregation in dendrite, and the amount of secondary precipitates according to casting parameters at a given alloy. In order to validate the model calculations, well-controlled casting experiments will be performed for Mg and Al alloys. In addition, diffusion couple experiments will be carried out to determine the diffusivities of various solutes in Mg alloys.The kinetic model and experiment can give deep scientific understanding of the solidification process of Mg and Al alloys. The kinetic solidification model can be eventually linked directly or indirectly to CFD simulation tools to predict the as-cast microstructure. Many casting companies in Canada including Alcan, Novelis and Sapa and final materials users like GM-Canada will be able to use the developed knowledge in their optimization of casting processes and the development of new materials. 4 Ph.D. students and 0.5 PDF will be trained over 5 years of the proposed research program.

候选人研究的最终目标是开发基于热力学数据库和动力学模型的高温工业冶金过程虚拟模拟工具。为了实现这一目标，之前的发现补助金（DG）重点关注火法冶金和合金热力学数据库的开发。许多热力学数据库是 DG 和过去五年其他研究资助的成果。在此 DG 中，候选人希望开发一个动力学凝固模型，以将此类热力学数据库用于实际铸造过程。大多数轻合金产品是通过铸造工艺生产的。因此，铸态显微组织是控制力学性能的决定因素之一。然而，铸态微观结构随铸造参数的演变仍未得到很好的研究。在铸造行业中，由 FLUENT 和 MAGMA 等商业软件包执行的计算流体动力学和热通量模拟主要用于了解非常复杂的铸模中的填充行为。不幸的是，此类软件无法提供有关铸造条件的准确微观结构信息。另一方面，相场建模被用来模拟2维和3维视图中铸态微观结构的发展，但计算速度太慢，无法直接应用于多元合金的实际铸造模拟。因此，需要一个简单但实​​用的动力学微观结构模拟模型来进行铸造材料的计算设计。在目前的研究计划中，将开发一种具有用户界面的多功能一维微观结构凝固模型，以涵盖各种铸造条件下的各种商用镁和铝合金。目前还没有适用于镁和铝合金的专用凝固模拟工具。在过去的几年里，该候选人的研究小组开展了基础和全面的铸造实验，以了解Mg-Al-Zn合金铸态微观结构的演变，并开展了Mg单晶扩散偶实验，以测量Mg-Al和Mg-Zn体系中的扩散率。一维微观结构凝固模型将考虑解释凝固过程中微观结构发展的所有关键凝固理论。此外，可以计算固相线、液相线和平衡第二相的热力学数据库将动态链接到动力学凝固模型。该凝固模型将在短时间内（小于 10 分钟）计算所有重要的凝固微观结构特征，例如根据给定合金的铸造参数，一次和二次枝晶间距、枝晶中的溶质偏析以及二次析出物的量。为了验证模型计算，将对镁和铝合金进行良好控制的铸造实验。此外，还将进行扩散偶实验，以确定镁合金中各种溶质的扩散系数。动力学模型和实验可以对镁和铝合金的凝固过程有深入的科学认识。动力学凝固模型最终可以直接或间接连接到 CFD 模拟工具来预测铸态微观结构。加拿大的许多铸造公司（包括 Alcan、Novelis 和 Sapa）以及最终材料用户（如 GM-Canada）将能够利用所开发的知识来优化铸造工艺和开发新材料。 4 博士学生和 0.5 PDF 将在拟议研究计划的 5 年时间内接受培训。