微重力条件下单晶合金的凝固生长

发布时间：2018-03-08 03:21

本文选题：空间　切入点：微重力　出处：《中国材料进展》2017年04期 　论文类型：期刊论文

【摘要】：单晶合金由于没有晶界缺陷而具有特殊的理化性能,如镍基单晶高温合金是先进航空航天发动机和燃气涡轮发动机关键材料,具有优异的高温使役性能。单晶合金的特色结构决定了它只能通过凝固的方式获得,因而凝固过程对单晶合金的组织结构、成分分布乃至理化性能具有难以磨灭的影响。如以枝晶结构为主要特征的单晶合金中的枝晶结构参数、合金元素的宏观与微观偏析都与凝固过程参数(如凝固速度、温度梯度等)密切相关。研究表明,重力导致的各项效应(如浮力对流、沉降和流体静压等)直接或间接地影响凝固过程参数,并且是导致成分偏析和凝固缺陷的重要原因。但在常规地面条件下由于无法有效去除重力影响,因而难以清晰揭示凝固过程中的重力效应及其作用规律。而在微重力环境中,这一难题将迎刃而解。因此,近些年来国内外一些学者利用空间或模拟微重力环境,对重力对单晶凝固行为的影响及其在缺陷形成中的作用进行了研究。这些研究对于获得良好的单晶凝固组织、避免凝固缺陷的形成,以及提高单晶合金的质量和性能都有着重要的意义。综述了目前国内外微重力下单晶生长研究的相关进展,并对未来研究进行了展望。
[Abstract]:Single crystal alloys have special physical and chemical properties due to their absence of grain boundary defects, such as nickel based single crystal superalloys are key materials for advanced aeronautical and aerospace engines and gas turbine engines. The unique structure of the single crystal alloy determines that it can only be obtained by solidification, thus the microstructure of the single crystal alloy is affected by the solidification process. The composition distribution and even the physical and chemical properties have indelible effects, such as dendritic structure parameters in single crystal alloy, macroscopical and microscopic segregation of alloy elements and solidification process parameters (such as solidification rate, etc.). Studies have shown that the effects of gravity (such as buoyant convection, sedimentation and hydrostatic pressure, etc.) directly or indirectly affect the parameters of the solidification process. It is also an important cause of composition segregation and solidification defects. However, it is difficult to clearly reveal the gravity effect and its action law in the microgravity environment because the gravity effect can not be effectively removed under conventional ground conditions. Therefore, in recent years, some scholars at home and abroad have used space or simulated microgravity environment, The effect of gravity on solidification behavior of single crystal and its role in the formation of defects are studied. It is of great significance to improve the quality and properties of single crystal alloys. The research progress of single crystal growth under microgravity at home and abroad is reviewed and the future research is prospected.
【作者单位】：中国科学院金属研究所中国科学院核用材料与安全评价重点实验室;
【基金】：国家自然科学基金资助项目(51171196) 载人航天工程项目(TGJZ800-2-RW024)
【分类号】：TG132.3

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