DD8镍基高温合金单晶制备中的杂晶长大机制

研究了ＤＤ８镍基高温合金单晶制备中择优生长晶向偏离热流杂晶的长大机制。实验结果表明：在一定条件下择优生长晶向偏离热流方向的晶粒能够淘汰择优生长晶向平行于热流方向的晶粒。研究表明，镍基高温合金单晶制备中的晶粒淘汰并不取决于择优生长晶向与热流方向平行，而是晶粒枝晶的三维相对位置，这很好地解释了高温合金单晶制备时经常发生的预定晶向之外的杂晶长大现象。

A STUDY ON MECHANISM OF MISORIENTED GRAIN GROWTH IN SINGLE-CRYSTAL MANUFACTURE OF DD8 NICKEL BASED SUPERALLOY

The growth mechanism of misoriented grains whoes preferred crystal growth direction deviates from heat gradient direction in single crystal manufacture of DD8 nickel based superalloy has been investigated. Experimental results show that under a certain condition these grains can eliminate those parallel to the heat gradient. It is indicated that the elimination process of grains in the single crystal manufacture of nickel based superalloy does not depend on parallelism of the preferred crystal growth direction to the heat gradient direction, but the three dimensional relative position of dendrites in grain, which gives a good explanation to the phenomenon of the growth of misoriented grain without predetermined crystal direction, that frequently occurs in the single crystal manufacture of high temperature superalloy.