L1_0结构TiAl中超位错分解宽度研究

STUDY ON THE SUPERDISLOCATION DISSOCIATION WIDTHS IN L1_0 TiAl

研究了弹性各向异性、超位错分解组态,变形温度及层片界面对Ｌ１ｏ结构ＴｉＡｌ合金中超位错分解宽度的影响作用．计算结果表明．同弹性各向同性相比,弹性各向异性减小了超位错的分解宽度,并且,使螺型超位错和刃型超位错的分解宽度差别减小．超位错发生三重或四重分解时,形成内禀性层错(ＳＩＳＦ)的分解宽度小于其发生二重分解时的分解宽度．非共面分解对超位错的分解宽度也有一定的影响,随分解位错的Ｂｕｒｇｅｒｓ矢量不同而不同．实验结果表明．温度变化对＜１０１]型超位错的分解宽度几乎没有影响,显示了剪切模量和层错能随温度变化而具有相同的变化趋势．＜１０１]型超位错在γ/γ层片界面附近的分解宽度不同于γ层片内,位错分解位置愈靠近γ/γ层片界面,分解宽度愈窄．

The effects of anisotropic elasticity, superdislocation dissociation configurations, deformation temperatures as well as lamellar interfaces on the superdislocation dissociation widths have been studied. The calculation results showed that anisotropic elasticity made both the superdislocation dissociation widths and the difference between edge and screw superdislocation dissociation widths become smaller comparing with isotropic elasticity. The superdislocation dissociation widths of the superlattice intrinsic stacking fault (SISF) in the 3-fold or 4-fold dissociations were calculated to be smaller than that in 2-fold dissociation. The superdislocation dissociation widths were also affected by the non-coplanar dissociation configuration, the variation of which was with the Burgers vectors of dissociated superdislocations. The experimental results showed that deformation temperatures had little effect on the <101] superdislocation dissociation widths, implying that the shear modulus and stacking fault energy have the same changeable tender with temperatures. The dissociation widths of <101] superdislocations near the lamellar interfaces of γ/γ type were different with that inside the γ lamellar, the nearer the distance, the narrower the dissociation widths.