Mechanism of competitive growth during directional solidification of a nickel-base superalloy in a three-dimensional reference frame
Mechanism of competitive growth during directional solidification of a nickel-base superalloy in a three-dimensional reference frame
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DOI：
10.1016/j.actamat.2012.04.002
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发表时间：
2012-05
期刊：
影响因子：
9.4
通讯作者：
Xiangbin Meng;Q. Lu;Xu Zhang;Jinguo Li;Z. Chen;Y. Wang;Yanfei Zhou;T. Jin;Xiang Sun
中科院分区：
文献类型：
--
作者：
Xiangbin Meng;Q. Lu;Xu Zhang;Jinguo Li;Z. Chen;Y. Wang;Yanfei Zhou;T. Jin;Xiang Sun
通过模拟和实验两种方法研究了定向凝固过程中双晶试样的组织演变，探讨了竞争生长的机理。提出了一种新的双晶样品的取向关系——非单平面情况，将双晶样品的取向关系从二维扩展到三维。结果表明：在非均匀面情况下，有利取向晶粒在偏离模壁的不利取向晶粒初生枝晶的侧隙中生长出新的枝晶，从而超越了不利取向晶粒；在此过程中，发现晶界向两个方向移动，一个方向垂直于晶界，另一个方向平行于晶界。为了描述枝晶生长的状态，构造了一个三维参考系。在这一参考框架下，竞争增长的机制可以分为收敛情况、非单平面情况和发散情况。仿真结果与实验结果吻合较好。
The microstructure evolution of bicrystal samples during directional solidification was studied, both by simulation and experiment, to explore the mechanism of competitive growth. A new orientation relationship of bicrystal samples, the non-uniplanar case, is proposed, which expands the orientation relationship of bicrystal samples from two dimensions to three dimensions. The results show that, in the non-uniplanar case, the favorably oriented grain overgrows the unfavorably oriented grain by developing new dendrites in the lateral gap where the primary dendrites of the unfavorably oriented grain diverge from the mold wall. During this process, the grain boundary is found to move in two directions, one perpendicular to the grain boundary and the other parallel to the grain boundary. To characterize the state of dendrite growth, a three-dimensional reference frame is constructed. In this reference frame, the mechanism of competitive growth can be categorized as a converging case, a non-uniplanar case and a diverging case. Furthermore, the simulation results are in good agreement with the experimental findings.