基于摆振（LAO）与超声复合的镁合金半连续流变铸造凝固规律及其控制

The law of the billet preparation process and its control is the key to obtain high quality billet, and the microstructure evolution law and computer simulation is the main means. Previous jobs of applicants have obtained the law of microstructure evolution and basic mode in the rheologicall process of magnesium alloy. The next step of work aims at using experiments, theory and research methods of combination of modeling and simulation, to study the semi-continuous rheological casting of magnesium alloy, which ensures integration of performance and property after near net shape forming. We would like to make achievements in the homogenization theory and regulation of slurry of massive high quality magnesium alloy, the mold optimum design and precise control of multi-scale modeling and simulation based on the semi-continuous rheological casting technology of magnesium alloys and development with independent intellectual property rights advanced magnesium alloy semi-continuous rheological casting technology，..In order to promote the industrialization of semi-solid forming in China, the overall semi-continuous rheocasting forming technology progress, we hope to meet the needs of aerospace, automobile manufacturing and other manufacturing areas on the advanced semi-continuous rheocasting forming of magnesium alloys.

坯锭制备过程的凝固规律及其控制是获得优质坯锭消除偏析和热裂缺陷的关键，而其中微观组织演变规律及其计算机模拟又是其中的主要手段。申请者前期工作已经获得了镁合金流变过程中微观组织演变规律以及基本模型，下一步的工作旨在采用实验、理论和建模仿真有机结合的研究方法，以研究镁合金半连续流变铸造、实现成形成性一体化的近净成形为主线，在大体积高质量镁合金低固相率浆料均匀化理论与调控，基于多尺度建模仿真的镁合金半连续流变铸造全过程工艺与模具的优化设计与精确控制等重要理论研究方面取得突破，发展具有自主知识产权的镁合金半连续流变铸造先进成形技术，预测并消除偏析与热裂带来的危害。为推动我国半固态成形的工业化、半连续流变铸造整体成形技术的进步，满足航空航天、车辆制造等制造领域对镁合金半连续流变铸造先进成形的重大、急迫需求做出贡献。

连续制备高质量非枝晶半固态浆料是制备高质量镁合金铸锭的前提，本项目采用摆振超声复合方法连续制备半固态浆料，利用PF-LBM耦合方法对摆振超声复合凝固规律进行研究，通过三维重构和多种表征参量对半固态浆料质量进行衡量。另外为了改善镁合金综合性能，本项目还研究了复合稀土微合金化镁合金研究、复合稀土微合金化与高能超声复合对镁合金微观组织及力学性能的研究。获得了以下重要成果：1）基于摆振超声复合半固态浆料制备技术,获得了摆振工艺参数对镁合金显微组织影响规律;2）建立了相场流场晶粒运动耦合下镁合金微观组织演变模型，研究并获得镁合金的凝固特性;3）完善半固态浆料质量表征手段及衡量标准：固相分数温度敏感系数、晶粒大小、晶粒形状、D指数初生相晶粒分布因子、固相分数、晶粒密度及微观组织三维重构;4)基于热平衡原理，开发了内冷搅拌法快速制备半固态浆料新工艺，改善了镁合金微观组织;5)通过复合稀土微合金化和高能超声作用，改善了镁合金微观，提高了综合力学性能。