(中国科学院 金属研究所， 沈阳 110016)
摘 要: 用光学显微镜观察了沿［001］，［011］和［111］方向生长的镍基单晶高温合金的枝晶形态。结果表明，以枝晶界面生长的单晶中生长方向完全由择优取向〈001〉决定，［001］方向中形成平行于轴向的枝晶，［011］和［111］方向中由于不同取向的枝晶交错生长，形成多种位向的亚晶界。在垂直于枝晶方向的｛001｝面内测定的一次枝晶间距，按［001］→［011］→［111］次序增大。用电子探针测定了不同取向中合金元素的偏析比，Al，Co，W的偏析情况不受晶体取向影响，Ti和Cr的偏析比按［001］→［011］→［111］的顺序减小，Ta和Mo的偏析程度无确切变化规律。各元素在不同取向中偏析的变化是由元素的扩散能力和枝晶空间构形共同决定的。
关键字: 高温合金；晶体取向；枝晶；偏析
microstructure and segregation of
Ni base single crystal superalloy
（Institute of Metal Research，The Chinese Academy of Science，
Shenyang 110016, China）
Abstract:The dendritic morphologies of a Ni base single crystal superalloy in［001］,［011］ and ［111］ orientations were observed by optic microscope. The results show that the dendrite direction is only determined by preferential 〈001〉 orientation. The primary dendrites parallel to the axis in ［001］ orientation. The subgrain boundary inclining to the axis is formed in ［011］ and ［111］ be cause of the crossing of dendrites in different directions. The primary dendrites spacing was measured in ｛001｝ plane normal to the dendrites growth direction. It increases in ［001］→［011］→［111］ order. The segregation of each element w as determined by EDX method. The segregation of Al，Co and W is not influenced by crystal orientation , and the segregation ratios of Ti and Cr decrease in order of ［001］→［011 ］→［111］，while the segregation of Ta and Mo displays no obvious tendency. The change of segregation of alloying elements in different orientation is the result of joint effect of diffusion ability and dendrite configurations.
Key words: superalloy; crystal orientation; dendrite; segregation
