(1.西安工业学院42号信箱，西安710032；
2.西北工业大学，西安710072)
摘 要: 利用超高梯度快速定向凝固装置，对DZ22合金在快速定向凝固下的枝晶组织和显微偏析进行了研究。实验结果表明：快速定向凝固的一次枝晶间距和二次枝晶间距及冷却速率随凝固速率变化有一极值。在凝固速率815μm／s时，枝晶间距(λ1，λ2)为最小，而冷却速率为最大。各元素显微偏析程度随冷却速率增大而减小。除Hf元素外，在最大冷却速率，54℃／s(R=815μm／s)时，其余元素的偏析比均趋于1。
关键字: 高温合金 定向凝固 显微偏析
UNDER UNIDIRECTIONAL SOLIDIFICATION WITH HIGH
TEMPERATURE GRADIENT AND RAPID GROWTH RATE
（1.Box 42,Xi′an Institute of Technology,Xi′an 710032
2．Northwest Polytechnic University,Xi′an 710072）
Abstract:Using an unidirectional solidification device which offers the super-high temperature gradient and the rapid growth rate of solidification, the dendritic structures and the dendritic segregation of DZ22 superalloy were investigated under the rapid unidirectional solidification. Experimental results showed that the first dendritic
arm space, the second dendritic arm space and the cooling rate all had an extreme value respectively with solidifying rate increasing under the rapid unidirectional solidification. At solidifying rate 815μm/s, two kinds of dendriticarm space were minimum but the cooling rate was maximum. The microsegregation of each element decreased with increasing cooling rate. The segregation ratios of the elements all tended to 1 at maximum cooling rate except element Hf.
Key words: superalloy unidirectional solidification microsegregation
