定向凝固过程中的晶粒竞争生长机制研究

项目名称： 定向凝固过程中的晶粒竞争生长机制研究

项目编号： No.51271186

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 一般工业技术

项目作者： 周亦胄

作者单位： 中国科学院金属研究所

项目金额： 80万元

中文摘要： 定向凝固技术广泛应用于航空发动机和燃气轮机的高温合金叶片制造，凝固过程中的晶粒竞争生长是决定能否获得合格单晶以及定向叶片的一个关键因素，同时也是金属凝固领域的一个重要科学问题。申请人的前期研究发现目前用于描述晶粒竞争生长机制的Walton-Chalmers模型与实验结果存在矛盾。但是，已有的研究结果还不能揭示控制晶粒竞争生长的物理机制，因此不能提出完善的模型。本项目通过定向凝固工艺参数、试样尺度、合金组元与含量的变化性实验以及模拟计算，分别揭示温度场、流场、溶质场在晶粒选择与淘汰过程的作用，澄清控制晶粒竞争生长的主导因素，建立晶粒竞争生长机制模型，拓展人们对定向凝固过程的认识，从而更有效地利用定向凝固技术制备高温合金部件。

中文关键词： 定向凝固；竞争生长；溶质场；温度场；流场

英文摘要： Directional solidification has been widely used to produce aero-engine and gas turbine blades of Ni-base superalloys. A preferred crystallographic orientation is produced in the directional solidification process due to competitive grain growth. Numerous beneficial effects were demonstrated because of the introduction of a preferred grain orientation with a low modulus parallel to the main stress axis and the elimination of grain boundaries perpendicular to the same stress axis. It is therefore important to study the issue of competitive grain growth from the both aspects of science and engineering. The generally accepted model for competitive grain growth was proposed by Walton and Chalmers. However, the recent experimental results in our works were not in accordance with Walton and Chalmers model. Since the present results from our works and literatures are not able to tell the fundamental mechanism dominating the competitive grain growth, a reasonable model has not been built in our works. In order to find the key factor dominating the competitive grain growth, the present project explores the effects of thermal field, fluid field and solutal field on grain selection by means of changing the solidification parameters, sample geometries and alloy contents in the casting experiments, respectively. Based on the

英文关键词： Directional solidification；Competitive growth；Solute field；Thermal field；Flow field