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研究了螺旋段在选晶过程中的作用.基于金相及EBSD实验结果,指出在晶粒竞争生长过程中,晶粒二次臂取向和初始位置分布特征综合决定了晶粒的竞争优势.总结提出了选晶过程的两个几何限制机理:水平方向的二次臂竞争促进作用和竖直方向的一次臂限制作用.两种模型成功解释了螺旋段对选晶过程的作用.采用修正的元胞自动机(MCA)技术,对螺旋段的晶粒竞争生长过程进行了模拟.研究了晶粒结构及晶体取向随定向凝固过程的变化规律,并与实验结果进行了对比,两者吻合较好.基于模拟与实验的研究,获得了螺旋参数对选晶行为的影响规律及作用机理,提出了选晶器螺旋段的设计准则.
Based on the metallographic and EBSD experimental results, it is pointed out that in the course of competitive growth of grains, the quadratic arm orientations and the initial distribution characteristics of the grains determine the competitive advantage of the grains. Two geometrical limitation mechanisms of the crystal selection process are proposed: the horizontal-direction secondary arm competition promotion and the vertical-direction one-arm limitation.The two models successfully explain the effect of the spiral segment on the selection process.Using the modified element Cellular automaton (MCA) was used to simulate the grain growth process in the spiral segment.The variation of grain structure and crystal orientation with directional solidification process was investigated and compared with the experimental results Based on the research of simulation and experiment, the influence law and mechanism of spiral parameter on the crystallization behavior were obtained, and the design criterion of spiral segment of crystal selector was proposed.