(1. 中南大學(xué) 粉末冶金國家重點實驗室，長沙 410083；
2. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 采用光學(xué)顯微鏡、掃描電鏡及透射電鏡研究微量B和Y對鑄造Ti-Al-Nb-W合金顯微組織的影響。結(jié)果表明：Ti-47Al-4Nb-0.6W合金的基本凝固路線為L→β+L→(β+α)+L→(β+α)+γ→α+γ→(α+γL)+γ→(α2+γL)+γ，添加微量B和Y并未改變其基本凝固路徑；微量B元素在合金中以短棒狀TiB2相存在，細化了鑄造Ti-47Al-4Nb-0.6W合金的晶團尺寸及片層間距；微量稀土Y元素主要以Y2O3氧化物顆粒的形式分布于片層晶團界面處，在B和Y的共同作用下，合金的片層晶團尺寸以及片層間距進一步減小。
關(guān)鍵字: TiAl基合金；顯微組織；鑄造合金；B；Y
（1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The effects of trace elements B and Y on the microstructures of cast Ti-Al-Nb-W alloy were investigated by optical microscopy, scanning microscopy and transmission electron microscopy. The results show that the following sequence of phase transformations takes place during the solidification of the Ti-47Al-4Nb-0.6W alloy as: L→β+L→(β+α)+L→(β+α)+γ→α+γ→(α+γL)+γ→(α2+γL)+γ. The solidification sequence remains unchanged after adding of trace elements B and Y. With the addition of a small amount of element B, the original colony and lamellar sizes of the Ti-47Al-4Nb-0.6W alloy are refined due to the formation of short-stick shaped TiB2 phases. The rare earth element Y is mainly distributed along the boundaries of the colonies in the form of Y2O3 particles. A further refined microstructure can be obtained as a result of the combined effects of elements B and Y.
Key words: TiAl based alloy; microstructure; as-cast alloy; B; Y
