热变形过程动态沉淀与动态再结晶的协同效应的微观相场和实验研究

The dynamic precipitation and dynamic recrystallization may occur simultaneously during the thermal deformation of the alloys with high-temperature precipitates in solid-solution state. These two processes are inter-related and the corresponding outcome is known as synergistic effect of the dynamic precipitation and dynamic recrystallization. By exploiting this synergistic effect, we can achieve the dispersed precipitates and finer grains altogether and the dispersion strengthening and fine grain strengthening simultaneously. It will potentially improve the alloy's mechanical performances..In this project, we combine the plastic forming, dynamic precipitation, dynamic recrystallization and advanced simulation method to investigate the aluminum alloys with high-temperature precipitates. Based on computer simulation of microscopic phase filed, thermal simulation experiments, micro-analysis and performance testing, we explore the coupling effect of macro/nano stress induced dynamic precipitation, and uncover the mechanism of local stress-induced local phase transformation. In line with the critical elements of dynamic precipitation: the thermodynamics - - stability; microstructure - - dispersity, morphology, arrangement; crystallography - - crystal structure; and kinetic - - precipitation mechanism, the interaction pattern and mechanism between dynamic precipitation and dynamic recrystallization are discussed. We achieve performance response relation to synergistic effect and clarify the contribution from the dispersion strengthening and fine grain strengthening. Overall, this scientific study is extracted from the formation mechanism of double-refined microstructure and dual-strengthen coordination in material manufacture and production and will provide theoretical support for the integrated design of process, organization and performance in thermal deformation.

含高温沉淀相的合金在固溶态热变形，可同时发生动态沉淀与动态再结晶，且二者相互影响，称为动态沉淀与动态再结晶的协同效应。合理控制协同效应，可得到弥散沉淀相和细小晶粒的双细化组织，实现弥散强化与细晶强化的双强化配合，对改善合金性能有大的潜力。.本项目将塑性成形、动态沉淀、动态再结晶、先进模拟方法的研究相结合，以含高温沉淀相的铝合金为对象，采用微观相场模拟、热模拟实验、微观分析、性能测试，研究宏/纳观应力耦合效应诱发动态沉淀，揭示局域应力诱发局域相变的机制；根据动态沉淀相的关键要素，从热力学- - 稳定性，组织学- - 弥散度、形貌、排列，结构学- - 晶体结构，动力学- - 沉淀机制，探讨动态沉淀与动态再结晶的相互作用规律与机制；得出性能的响应关系，明晰弥散强化、细晶强化的贡献；以材料制备加工的双细化组织、双强化配合的形成机制为背景，凝练出科学问题，可为热变形的工艺、组织、性能一体化设计，提供理论支撑。

本项目将塑性成形、动态沉淀、动态再结晶、先进模拟方法的研究相结合，以含高温沉淀相的铝合金为对象，采用微观相场模拟、热模拟实验、微观分析、性能测试，力学冶金与物理冶金理论相结合，研究宏/纳观应力耦合效应诱发动态沉淀，揭示局域应力诱发局域相变的机制。.应力场引入微观相场法，在非均匀弹性各向异性的（半）共格系统，追踪元素扩散的各向异性。根据动态沉淀的关键要素，从热力学——稳定性，组织学——弥散度、形貌、排列，结构学——晶体结构，动力学——沉淀机制，探讨动态沉淀与动态再结晶的相互作用规律与机制。.通过本项目的研究，探明动态沉淀与动态再结晶的协同效应对外应力、相界错配应力、两相模量差、弹性取向异性因子、相界取向等的响应关系，明晰协同效应与相界结构、晶体结构、组织形貌、沉淀相热力学状态的内在联系。揭示不同空间尺度微结构因素对动态沉淀与动态再结晶的协同效应的影响机制，阐明热变形早期至后期的动态沉淀与动态再结晶的协同效应,定量预测原理可用于具有良好变形能力的合金。.本项目研究得出性能对动态沉淀与动态再结晶的协同效应的响应关系，明晰弥散强化、细晶强化的贡献，以序参数、结构函数、相关联函数、标度函数等对其定量描述。以材料制备加工的双细化组织、双强化配合的形成机制为背景，凝练出科学问题，可为热变形的工艺、组织、性能一体化设计，提供理论支撑。.完成了计划研究内容，实现了预期目标。有55篇论文在《Journal of Alloys and Compounds》、《Computational Materials Science》、《Solid State Communications》、《Rsc Advances》、《Transactions of nonferrous metals society of China》、《Acta Physica Sinica》、《Chinese Physics B 》《Physica B-Condensed Matter》、《Science in China Series G》等等刊物上发表，超额完成计划的论文数量，有47篇被SCI收录和41篇被EI收录。本项目的研究成果申报国家发明专利4项，获陕西省科学技术二等奖1项。参加3次境外学术会议，5次境内学术会议并做口头报告。有13名研究生参加了本项目的研究，培养出博士生5名、硕士生8名，完成计划的培养人才数量。