稀土诱发共晶反应细化半固态铝合金组织研究

Semisolid alloy process is one of techniques to realize the high performance precision forming manufacturing for metal, and the core of the scientific connotation on preparation of semisolid alloy slurry with high quality is still how to control the alloy solidification. The research on the theory and technique of the refining microstructure in semisolid alloy has the important scientific significance for improving the employing properties of aluminum alloy and realizing the high performance precision forming manufacturing of metal. Based on the eutectic reaction induced by rare earth (RE) in semisolid alloy melt in this project, and taking the research on refining mechanism and effect of RE-Al eutectic reaction and reacting product on microstructure in semisolid Al alloy as the major clue, as well as taking the study on non-equilibrium solidification in RE-Al alloy system under the electromagnetic disturbance as the bridge, some investigations will be carried out for the use of metal solidification theory, nonlinear scientific theory, rare earth metallurgy and so on. The interaction between RE and Al and the affecting factor on the interaction are researched during the non-equilibrium solidification. The refining effects of eutectic reaction induced by RE in Al melt on primary phase in semisolid Al alloy are investigated. The non-linear characteristic of the RE-Al eutectic reaction is revealed through analyzing the dissipative structure in RE-Al system during the non-equilibrium solidification. The connection between the eutectic reaction induced by RE in Al alloy and the refining technique on microstructure in Al alloy is established, which plays a foundation for founding the complex RE-electromagnetic field refining technique and setting up the new refining theory.

合金的半固态加工是实现金属高性能精确成形制造的技术之一，而制备高质量半固态合金浆料的科学内涵核心仍是如何调控合金的凝固问题。半固态合金凝固组织的晶粒细化理论和技术的研究对于提高半固态合金使用性能和实现金属高性能精确成形制造具有重要的科学意义。本项目以稀土在半固态铝合金熔体中诱发的共晶反应为基础；以稀土-铝共晶反应过程及其产物对半固态铝合金凝固组织的细化机制和效应研究为主线；以稀土-铝系统在电磁扰动下的非平衡凝固过程研究为桥梁；将应用金属凝固理论、非线性科学理论、稀土冶金学等，研究非平衡凝固时稀土与铝的相互作用与影响因素，探索稀土在铝合金熔体中诱发共晶反应对半固态铝合金初生相的细化效应；通过剖析非平衡凝固时稀土-铝系统的耗散结构揭示稀土-铝共晶反应的非线性特征，建立稀土在铝合金中诱发共晶反应与铝合金凝固组织的细化技术两者之间的联系，为创建稀土-电磁复合细化技术和建立新的细化理论研究奠定基础。

合金的半固态加工是实现金属高性能精确成形制造的技术之一，而制备高质量半固态合金浆料的科学内涵核心仍是如何调控合金的凝固问题。半固态合金凝固组织的晶粒细化理论和技术的研究对于提高半固态合金使用性能和实现金属高性能精确成形制造具有重要的科学意义。本项目以稀土在半固态铝合金熔体中诱发的共晶反应为基础；以稀土-铝共晶反应过程及其产物对半固态铝合金凝固组织的细化机制和效应研究为主线；以稀土-铝系统在电磁扰动下的非平衡凝固过程研究为桥梁；开展稀土-铝合金体系非平衡凝固过程的研究，非平衡凝固下稀土-铝共晶反应体系耗散结构特征的研究，稀土-铝共晶反应临界参数变化研究，浇注工艺条件对稀土-铝共晶反应过程的影响以及多重细化效应的电磁搅拌-稀土细化机理研究。本项目应用金属凝固理论、非线性科学理论、稀土冶金学等，研究非平衡凝固时稀土与铝的相互作用与影响因素，探索稀土在铝合金熔体中诱发共晶反应对半固态铝合金初生相的细化机制与效应。通过实验研究和理论分析，开发了多种更优越的制备半固态铝合金浆料新技术，研究了单一和多元稀土与铝合金熔体的相互作用以及诱发的共晶反应细化半固态铝合金凝固组织的效益；探索了电磁搅拌与凝固工艺参数交互作用下的多维传质和多重细化机制。通过数值计算，获得了电磁搅拌装置中坩埚内磁场感应强度分布部规律，揭示了半固态合金熔体在电磁场作用下的流动特性。应用二维错配度理论，阐明了稀土铝化合物细化半固态初生相的可行性与机理。提出了非圆坩埚的设计概念并研究了坩埚尺寸尺寸和电磁频率对半固态A356铝合金浆料流动的影响。通过剖析非平衡凝固时稀土-铝系统的耗散结构揭示稀土-铝共晶反应的非线性特征，建立稀土在铝合金中诱发共晶反应与铝合金凝固组织的细化技术两者之间的联系，为创建稀土-电磁复合细化技术和建立新的细化理论研究奠定基础。

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