(1. 東北大學(xué) 材料與冶金學(xué)院，沈陽 110004；
2. 中國科學(xué)院 金屬研究所，沈陽 110016；
3. 沈陽理工大學(xué) 環(huán)境與化學(xué)工程學(xué)院，沈陽 110168)
摘 要: 利用硅−碳管爐制備凝固樣品，采用金相顯微鏡觀察DZ68合金的凝固過程，利用電子探針測定DZ68合金凝固過程中的元素含量，研究DZ68合金的凝固過程及合金元素、雜質(zhì)元素的偏析行為。結(jié)果表明：DZ68合金的凝固過程主要在1 370~1 310 ℃內(nèi)完成，合金的終凝溫度介于1 180~1 200 ℃之間；DZ68合金中主元素W、Re、Ta、Al的偏析系數(shù)經(jīng)測定分別為2.2、4.5、0.58和0.8，其中W和Re為強(qiáng)烈負(fù)偏析元素，Ta是強(qiáng)烈正偏析元素；有害雜質(zhì)元素S、P、B和Si在枝晶間發(fā)生嚴(yán)重偏聚。熱力學(xué)分析表明，這些偏聚的雜質(zhì)元素在枝晶間可能形成Ni3P、Ni3S2和M3B2等低熔點(diǎn)化合物，從理論上解釋了DZ68合金終凝溫度降低的原因。
關(guān)鍵字: DZ68；高溫合金；凝固行為；偏析
（1. School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China;
2. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;
3. School of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang 110168, China）
Abstract: The samples of solidification were produced by the silicon-carbon tube. The whole solidification of DZ68 alloy was observed by optical microscopy (OM). The content of element of DZ68 alloy during of solidification was measured by electronic probe micro analysis(EPMA). The solidification behavior and segregation of elements in the DZ68 alloy were studied. The results show that the solidification of DZ68 alloy mainly completes between 1 370 and 1 310 ℃, and the final set temperature is confirmed between 1 180 and 1 200 ℃. The segregation coefficients of W, Re, Ta and Al in DZ68 alloy are obtained as 2.2, 4.5, 0.58 and 0.8, respectively. The segregation coefficients of different elements show that W and Re are strong negative segregation elements and Ta is strong positive segregation element. The impurity elements of S, P, B and Si are severely clustered in the interdendritic area. The thermodynamical analysis shows that these elements are possible to form low melting compounds such as Ni3P, Ni3S2 and M3B2 in the interdendritic area, which explains the reason why the final setting temperature of DZ68 alloy decreases.
Key words: DZ68; superalloy; solidification; segregation
