基于相图计算的多元多相包共晶合金凝固过程模型化研究

It is an important trend in the development of materials science to understand, master and control the solidification process and solidification behavior of multi-component multiphase alloys. Quasiperitectic reaction, which has the characteristics of peritectic and eutectic, widely exists in industrial alloys, and has an important influence on materials preparation, development and application, is highly concerned by the solidification and material science. By combining the research methods of experimental study, theoretical modeling and numerical simulation, through the process of constructing microsegregation model, establishing solidification path algorithm, compiling simulation program, and carrying the quenching and directional solidification experiment, the solidification behavior and mechanism of the quasiperitectic AlCuMg alloy are studied. In this project, microsegregation, solidification path, and microstructure evolution of the quasiperitectic alloy are investigated, which can provides the theoretical basis, calculation model and key technology for the preparation and development of multi-component multiphase alloys. The implementation of this project can not only deepen the understanding of quasiperitectic alloy solidification behavior and enrich solidification theory of the multicomponent multiphase alloy, but also can be combined with the previous research to construct unified model and algorithm platform which can calculate the microsegregation and solidification path of ternary uniform, eutectic, quasiperitectic alloy. And this project can also provide the theory and experiment basis, to realize the optimization of composition and microstructure.

认知、掌握和控制多元多相合金凝固过程与凝固行为是当前材料科学发展的一个重要趋势。包共晶反应，兼有包晶与共晶反应的特点，广泛存在于常用工业合金并且对材料制备、研发与应用等有重要影响，正在受到凝固及材料学科的高度关注。本项目采用实验研究、理论建模与数值模拟相结合的研究方法，以AlCuMg包共晶合金凝固过程模型化为研究对象，通过建立微观偏析模型、构建凝固路径算法、进行液淬与定向凝固实验等过程，对包共晶合金凝固行为与机制等进行深入研究。探讨包共晶合金的微观偏析、凝固路径、组织演变等行为，为多元多相合金的制备与研发提供理论依据、计算模型和关键技术。本项目的实施深化了对包共晶合金凝固行为的认识，不但丰富了多元多相合金凝固理论，同时还将结合前期研究，构建可以计算三元匀晶、共晶、包共晶合金微观偏析及凝固路径的统一模型与算法平台，为实现多元多相合金的成分与组织优化，提供系统的理论和实验依据。

本项目以三元包共晶、共晶合金为研究对象，采用数值模拟、实验研究与理论分析相结合的方法，建立三元包共晶合金微观偏析模型与凝固路径算法，预测三元包共晶合金在不同却速度下的微观偏析、凝固路径、相组成与含量，分析三元包共晶合金凝固过程溶质分凝特性，包括：溶质分凝系数与冷却速度、平衡分凝系数、溶质扩散系数以及固相分数等的定量关系等；本项目基于Thermo-Calc相图计算，构建可以计算三元匀晶、共晶、包共晶三种类型合金凝固路径及微观偏析的统一算法平台，并编写成套的可执行程序，构建可以计算三元匀晶、共晶、包共晶合金微观偏析及凝固路径的统一模型与算法平台，为实现多元多相合金的成分与组织优化，提供系统的理论和实验依据；本项目通过凝固实验进一步研究三元包共晶合金的凝固机制、组织形态演变、相组成等，揭示了三元包共晶合金枝晶间微观偏析、凝固路径、溶质分凝特性、包共晶反应机制等，从而预测和控制此类合金微观偏析和组织的形成等，为充分发挥合金的综合性能打下坚实的理论基础。