具有相分解特性的高熵合金深过冷组织演化规律

Up till now,the high entropy alloys have been prepared by rapid solidification,mechanical alloying and powder metallurgy, however, little information about the microstructure and properties of high entropy alloys by undercooled process are reported. In the present study, FeCoNiCrAlxTM(TM is Mn or Cu) is undercooled by fluxing and cyclic superheating. The effect of undercooling degree, chemical composition and solidification path on the formation of phase is investigated to find out the non-equilibrium solidification characteristics of high entropy alloys, reveal the precipitation mechanism and crystal orientation of nano precipitated phase in high entropy alloys druing undercooling process,furthermore, the effect of nano precipitated phase on the mechanical properties of high entropy alloys will be also studied. our research efforts will contribute to the solidification theory of high entropy alloy and provide experimental basis for application in the field of structural materials.

目前为止，对多主元高熵合金的制备都是基于快速凝固、机械合金化和粉末冶金等工艺方法，而尚无对多主元高熵合金深过冷凝固组织和性能的研究。本项目以FeCoNiCrAlxTM(TM为Mn,Cu)合金为研究对象，采用深过冷凝固技术系统深入研究多主元高熵合金在凝固过程中不同的过冷度、化学成分及凝固路径条件下合金的相组成和相形成规律，以明确多主元高熵合金的非平衡凝固特征，并揭示多主元高熵合金深过冷凝固过程中纳米相析出机制及控制析出相的晶体取向，研究纳米析出相对力学性能的影响。本项目将丰富多主元高熵合金凝固理论，为多主元高熵合金在结构材料领域的应用提供理论和实验依据。

本项目采用实验和计算相结合的方法，系统研究FeCoNiCrAl系高熵合金的凝固相变行为，综合考虑了混合焓、混合熵、原子半径差、电负性、电子空位浓度等参数对Mo元素添加、Al/Ni、（Al+Ni）以及Al/Ti和（Al+Ti）对FeCoNiCrAl基高熵合金相稳定性的影响，建立FeCoNiCrAl基高熵合金相选择图谱. 为实验制备FeCoNiCrAl系高熵合金提供了理论指导。考察了（Al+Ni）和（Al+Ti）物质量的分数对热处理态的FeCoNiCrAl基高熵合金的组织影响。上述研究系统扩展了化学成分调节对FeCoNiCrAl系高熵合金的凝固相变行为，也可为相关体系的高熵合金材料设计和制备提供一种类比的研究模式。