大尺寸单晶叶片中小角度晶界的形成与演化
收稿日期: 2019-04-01
修回日期: 2019-07-25
网络出版日期: 2019-08-15
基金资助
国家自然科学基金项目(Nos.51771204);国家自然科学基金项目(U1732131);国家自然科学基金项目(51911530154);国家自然科学基金项目(51671196);国家自然科学基金项目(91860201);国家自然科学基金项目(51631008);国家科技重大专项项目(No.2017-VII-0008-0101)
Formation and Evolution of Low Angle Grain Boundary in Large-Scale Single Crystal Superalloy Blade
Received date: 2019-04-01
Revised date: 2019-07-25
Online published: 2019-08-15
Supported by
National Natural Science Foundation of China(Nos.51771204);National Natural Science Foundation of China(U1732131);National Natural Science Foundation of China(51911530154);National Natural Science Foundation of China(51671196);National Natural Science Foundation of China(91860201);National Natural Science Foundation of China(51631008);National Science and Technology Major Project(No.2017-VII-0008-0101)
通过EBSD和XCT等方法研究了大尺寸单晶叶片制备过程中小角度晶界的形成与演化过程。结果表明，在大尺寸单晶叶片生长过程中，沿单晶叶片生长方向，随叶片高度的增加，其横截面枝晶排列的规则程度越来越恶化；叶片出现小角度晶界，其取向差与产生频率随距离初始位置高度的增加而显著增加；晶体取向测试表明，扩展区枝晶取向分布较为集中，而叶身枝晶取向分散度增大，但仍分布在扩展区取向附近。小角度晶界产生的原因可能与模壳阻碍熔体收缩产生应力，进而导致二次枝晶转动有关。表面较大尺寸的孔洞有利于小角晶界的产生。此外，还发现取向相近、且靠近[001]取向的枝晶淘汰它们之间的杂晶后相撞而形成小角度晶界。
谢光 , 张少华 , 郑伟 , 张功 , 申健 , 卢玉章 , 郝红全 , 王莉 , 楼琅洪 , 张健 . 大尺寸单晶叶片中小角度晶界的形成与演化[J]. 金属学报, 2019 , 55(12) : 1527 -1536 . DOI: 10.11900/0412.1961.2019.00090
Ni-based single crystal (SX) superalloys are widely used for production of blades in gas turbines and aircraft engines for their superior mechanical performance at high temperatures. In this work, the formation and evolution of low angle grain boundary (LAGB) of a SX blade during directionally solified (DS) process were investigated by EBSD and XCT. It indicated that the alignment of dendrites was deteriorated with the increasing of the height along the growth direction during the DS process of SX blade. LAGBs were found in the SX blade. The misorientation angle and the frequency of LAGB were obviously enhanced with the increasing of the distance away from the initiated location of LAGB. Crystal orientation measurements showed that the orientation distribution of dendrites in the extended zone was concentrated, while the dispersion of dendrite orientation in the blade body increased, but it was still around that of the extended zone. The reason for the formation of LAGB may be related to the shell hindering the melt shrinkage which resulted in the production of the force and then led to the rotation of secondary dendrites. Larger size voids on the surface would be beneficial to the formation of LAGB. In addition, it was found that dendrites with the orientation approching [001] eliminated the stray grains between them and impinged to form LAGB.
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