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通过全片层γ TiAl基合金SEM原位拉伸实验以及对裂纹前方滑移面及解理面上的应力进行有限元计算 ,研究了片层界面在形核中的作用。当原裂纹与片层平行时 ,裂纹尖端滑移系的分切应力较小 ,滑移相对困难 ,片层面上的正应力比其它解理面上的正应力大 ,从而解理裂纹优先沿片层界面形核 ;当裂纹与片层界面垂直时 ,裂纹尖端很多滑移系上的分切应力较大 ,滑移相对容易 ,片层面上的正应力远比其它解理面上的正应力小 ,从而裂纹优先在跨γ片层的解理面上形核 ,片层界面成为滑移和裂纹扩展的障碍
In-situ tensile testing of full-thickness γ-TiAl-based alloys and finite element analysis of the stresses on the slip planes and cleavage planes in front of the crack were carried out to study the effect of lamellar interfaces on nucleation. When the original crack is parallel with the sheet, the shear stress of the slip system at the crack tip is smaller and the slippage is relatively difficult. The normal stress on the sheet surface is greater than the normal stress on other cleavage planes, Layer interface. When the crack is perpendicular to the interface of the lamella, the shear stress on many slip systems at the crack tip is larger and the slippage is relatively easy. The normal stress on the sheet plane is much smaller than the normal stress on other cleavage planes , So that the crack preferentially nucleates on the cleavage plane across the γ sheet and the sheet interface becomes an obstacle to slip and crack propagation