(中國(guó)科學(xué)院 金屬研究所， 沈陽(yáng) 110016)
摘 要: 用光學(xué)顯微鏡觀察了沿［001］，［011］和［111］方向生長(zhǎng)的鎳基單晶高溫合金的枝晶形態(tài)。結(jié)果表明，以枝晶界面生長(zhǎng)的單晶中生長(zhǎng)方向完全由擇優(yōu)取向〈001〉決定，［001］方向中形成平行于軸向的枝晶，［011］和［111］方向中由于不同取向的枝晶交錯(cuò)生長(zhǎng)，形成多種位向的亞晶界。在垂直于枝晶方向的｛001｝面內(nèi)測(cè)定的一次枝晶間距，按［001］→［011］→［111］次序增大。用電子探針測(cè)定了不同取向中合金元素的偏析比，Al，Co，W的偏析情況不受晶體取向影響，Ti和Cr的偏析比按［001］→［011］→［111］的順序減小，Ta和Mo的偏析程度無(wú)確切變化規(guī)律。各元素在不同取向中偏析的變化是由元素的擴(kuò)散能力和枝晶空間構(gòu)形共同決定的。
關(guān)鍵字: 高溫合金；晶體取向；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
