镍基高温合金熔体结构及其液-液结构转变机制研究

项目名称： 镍基高温合金熔体结构及其液-液结构转变机制研究

项目编号： No.51474147

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 矿业工程

项目作者： 孙宝德

作者单位： 上海交通大学

项目金额： 80万元

中文摘要： 航空发动机镍基高温合金关键部件，因其大尺寸、复杂结构及薄壁特征，导致精密铸造过程中充型的困难。升高浇注温度可提高充型能力，但是会导致厚大部位晶粒粗大、偏析加重等，降低结构件的服役性能。熔体超温处理工艺（HTTM）为缓解该矛盾提供了新的思路。目前，HTTM的理论机制仍无定论，但与尚未澄清的镍基高温合金熔体结构有关，尤其是其中可能存在的温度诱导的液-液结构转变。本项目拟采用从头算分子动力学模拟与X射线衍射、差热分析等实验手段相结合的方法对模型合金进行研究，阐明合金元素对镍基合金熔体结构的影响规律，探索镍基合金熔体可能存在的温度诱导的液-液结构转变，揭示其转变机制，探明合金熔体结构及液-液结构转变对合金的凝固过程及凝固组织的影响规律，为开发镍基高温合金的新型熔体超温处理工艺提供理论基础。

中文关键词： 高温合金；熔体结构；从头算分子动力学；液-液结构转变；凝固组织

英文摘要： Some key components of nickel-base superalloy in aeroengine, because of its large size , complex structure , and thin wall, the mold-filling difficulties exist in the investment casting process. Elevated pouring temperature can improve the filling capacity, but will result in coarse grains and more serious segregation in the thick parts, thus reduce the service performance of the components. The high temperature treatment of melt (HTTM) provides a new way to alleviate the contradiction. But, up to now, the HTTM mechanism is still unclear, but is expected to be related to the unclarified molten structure of the nickel-base superalloy, especially the possible temperature-induced liquid-liquid structural transition (LLST). By combining ab initio molecular dynamics (AIMD) simulations, X-ray diffraction (XRD), differential thermal analysis (DTA) and other experimental techniques, this project aims to clarify the effects of solute elements on the melt structure of nickel-base alloy, explore its possible temperature-induced LLST, the influences of the melt structure and possible LLST on the solidification process and the solidification structure of the model alloys. The research will provide a theoretical basis for the development of novel HTTM of nickel-base superalloy.

英文关键词： superalloy;melt structure;ab initio molecular dynamics;liquid to liquid structure transition;solidification microstructure