Effects of heat treatment on microstructure of directionally solidified Ti-45Al-8Nb-(W, B, Y) alloy

来源期刊：中国有色金属学报(英文版)2011年第1期

论文作者：丁贤飞 林均品 张来启 陈国良

文章页码：26 - 31

关键词：TiAl合金；定向凝固；热处理；显微组织；偏析

Key words：TiAl alloy; directional solidification; heat treatment; microstructure; segregation

摘    要：研究两种热处理制度对Bridgeman法制备的典型定向凝固Ti-45Al-8Nb-(W，B，Y)(摩尔分数，%)合金组织的影响。两种典型的定向凝固显微组织分别为胞状生长形貌全片层组织和枝晶状生长形貌块状组织，对其热处理发现：热处理1 250 °C，24 h+900 °C，30 min+AC能有效消除其定向凝固合金中的B2相，并将快速定向凝固时产生的块状组织转变为片层组织，在胞状间及枝晶臂上分别获得了宽度为150-200 μm和50-100 μm的柱状晶。热处理1 400 °C，2 h+900 °C，30 min+AC能同时消除B2相、块状组织及凝固偏析，但造成了晶粒的严重长大。热处理能有效改进定向凝固合金的显微组织。

Abstract: The effects of heat treatments on typical microstructures of directionally solidified (DS) Ti-45Al-8Nb-(W, B, Y) (molar fraction, %) alloys prepared by the Bridgeman method were studied. Two typical DS microstructures including full lamellae with cellular growth morphology and massive structure with dendritic growth morphology were examined. The results show that the heat treatment of 1250 °C for 24 h + 900 °C for 30 min+air cooling can efficiently eliminate the B2 phase in the DS alloys and change the massive structure of the rapid DS alloy into lamellar microstructure. Columnar lamellar colonies with widths of 150-200 μm and 50-100 μm respectively were observed in intercellular and dendritic arm regions. The heat treatment of 1 400 °C for 12 h+900 °C for 30 min+air cooling could simultaneously remove the B2 phase, massive structure and solidification segregations from the DS alloys, however, it caused severe growth of grains.