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采用ProCAST&CAFE模型,模拟了选晶法制备镍基单晶高温合金DD3过程中的晶粒组织演化。结果表明,选晶器引晶段的主要作用是优化晶粒取向,随着距引晶段底部距离的增加,<001>晶向与热流方向偏离角较大的晶粒逐渐被淘汰,到达距引晶段底部26 mm处时,<001>取向的晶粒与热流方向之间的夹角平均值小于10°。螺旋选晶段的主要作用是获得单一晶粒,其对晶粒的取向没有优化作用。螺旋选晶过程中,靠近螺旋通道外侧的晶粒因受到螺旋通道较强的几何阻碍逐渐失去生长空间,而靠近螺旋通道内侧的晶粒通常被选为最终的单晶。螺旋选晶段对晶粒的选择或淘汰与该晶粒在螺旋通道内所处的位置(螺旋通道的内侧或外侧)有密切关系,而与晶粒的晶体学取向没有必然联系。
ProCAST & CAFE models were used to simulate the evolution of grain structure during the preparation of DD3 by Ni-based single crystal superalloy. The results show that the main role of the seeding section of the crystallizer is to optimize the grain orientation. With the increase of the distance from the bottom of the seeding section, the grains with larger deviation angle from the direction of the heat flow are gradually eliminated, The average angle between the <001> oriented grains and the direction of heat flow is less than 10 ° at 26 mm at the bottom of the seeding section. The main role of the spiral electret is to obtain a single grain, which does not optimize the orientation of the grain. During the process of spiral selection, the grains near the outer side of the spiral channel gradually lose their growth space due to the strong geometrical hindrance of the spiral channel, while the grains near the inner side of the spiral channel are usually selected as the final single crystal. The selection or elimination of the crystal grains by the spiral electret is closely related to the location of the crystal grains in the spiral channel (the inner side or the outer side of the spiral channel), but not related to the crystallographic orientation of the crystal grains.