γ—TiAl层状结构裂尖应力场的有限元分析

Stress Analysis of the Crack Tip in FullyLamellar

摘要:

根据γ-TiAl层状晶体（PST晶体）的微观结构，构造了可使用有限元计算的夹心基元。由有限元计算表明，当裂尖平行于片层时，裂尖前端所有滑移系上的分切应力都很小。即滑移较弱，而沿片层界面（它总是解理面之一）的正应力有最大值，这表明，裂尖将沿片层扩展，而且塑性小，当裂纹垂直于片层时，裂尖前端很多滑移系上的分切应力都很大，最大正应力并不在片层界面上，而总在跨片层的解理面上，这表明，裂尖在片层内解理，并且塑性很大。

Abstract:

A lamellar structural unit model of PST crystal used in finite element analysis has been built on the basis of studying the microstructure of PST crystal. The calculation indicates that as crack is parallel to the lamellae, the resolved shear stresses on all slip planes ahead of crack tip are low, and the slip is difficulty, while the normal stress on lamellar interface is higher than that on other cleavage planes, which results in crack nucleation along lamellar interfaces preferentially and low ductility. As the crack perpendicular to the lamellae, the resolved stress on many slip planes ahead of crack tip is much higher, and the slip is easy. The maximum normal stress on the translamellar cleavage planes rather than the lamellar interface, which results in crack nucleation along translamellar interfaces preferentially and good ductility.