(上海交通大學(xué)材料科學(xué)系， 上海 200030)
摘 要: 利用TEM原位應(yīng)變觀察技術(shù)研究了TiAl合金PST晶體中裂紋擴(kuò)展過(guò)程。發(fā)現(xiàn)界面與裂紋的交互作用與界面類(lèi)型有關(guān)，不對(duì)稱的偽孿晶界面(γ/γP)對(duì)裂紋擴(kuò)展的阻礙最強(qiáng)烈。片層界面以及二次裂紋導(dǎo)致的裂紋分叉是層狀組織韌化TiAl合金的重要原因。當(dāng)裂紋與片層界面的夾角不同時(shí)， γ相所表現(xiàn)的兩種截然不同的斷裂方式表明在TiAl 合金的脆性本質(zhì)中包含有位錯(cuò)動(dòng)力學(xué)的因素。
關(guān)鍵字: TiAl合金PST晶體 裂紋擴(kuò)展 位錯(cuò)動(dòng)力學(xué)
（Department of Materials Science, Shanghai Jiao Tong University, Shanghai 200030）
Abstract:Crack propagation processes in polysynthetically twinned (PST) crystals of TiAl were investigated by in-situ TEM observation. It was found that the influence of lamellar boundaries on the fracture behaviors is connected with the type of in terfaces, in which the asymmetrical γ/γP interface is the largest inhibition to crack growth. The crack kinks which result from lamellar interfaces and second microcracks play a dominant role on that TiAl alloys are toughened by lamellar structure. As the angle between tensile axis and lamellar interface varies, that two kinds of different fracture modes existed in γ phase indicates that dislocation dynamics may be an important reason on embrittlement of TiAl alloys.
Key words: PST crystals of TiAl crack propagation dislocation dynamics
