(1.北京科技大學(xué) 材料物理系， 北京 100083；
2.北京航空航天大學(xué) 材料科學(xué)與工程系， 北京 100083)
摘 要: 通過全片層 γ-TiAl基合金SEM原位拉伸實驗以及對裂紋前方滑移面及解理面上的應(yīng)力進(jìn)行有限元計算，研究了片層界面在形核中的作用。當(dāng)原裂紋與片層平行時，裂紋尖端滑移系的分切應(yīng)力較小，滑移相對困難，片層面上的正應(yīng)力比其它解理面上的正應(yīng)力大，從而解理裂紋優(yōu)先沿片層界面形核；當(dāng)裂紋與片層界面垂直時，裂紋尖端很多滑移系上的分切應(yīng)力較大，滑移相對容易，片層面上的正應(yīng)力遠(yuǎn)比其它解理面上的正應(yīng)力小，從而裂紋優(yōu)先在跨γ 片層的解理面上形核，片層界面成為滑移和裂紋擴(kuò)展的障礙。
關(guān)鍵字: γ-TiAl； 全片層結(jié)構(gòu)； 片層界面；裂紋形核； 有限元法
（1. Department of Materials Physics, University of Science and Technology Beijing, Beijing 100083, P.R.China;
2. Department of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083, P.R.China）
Abstract:The twofold effects of lamellar interface on crack nucleation in fully lamellar TiAl based alloys were investigated through in-situ SEMtechnique and stress analysis on cleavage planes using finite element method. When the crack is parallel to the lamellae, the resolved stresses on all slip planes ahead of crack tip is small, which makes the slips difficult; while the normalstresses on lamellar interfaces is higher than those on other cleavage planes, which results in crack nucleation along lamellar interfaces preferentially. When the crack is perpendicular to the lamellae, the resolved stresses on many slipplanes ahead of crack tip are much higher compared with the condition when the crack is parallel to the lamellae, which makes slips easy; while the normal stresses on lamellar interfaces are much smaller than those on other cleavage planes,which results in crack nucleation along trans-lamellar interfaces preferentially, and the lamellar interface is the hindrance of slip and crack propagation.
Key words: γ-TiAl based alloy； fully lamellar structure； lamellar interface； crack nucleation； finite element method
