通过对Ti_3Al+Nb金属间化合物在透射电子显微镜下的原位拉伸,研究了脆性材料中位错的发射,无位错区(DFZ)的形成及其本质,以及脆性微裂纹在DFZ中的形核和扩展,并用细观断裂力学研究了微裂纹的形核过程,结果表明,脆性裂纹也能发射大量位错并形成DFZ,发射位错后裂纹可能钝化也可能不钝化,DFZ是一个畸变很高的弹性区,其中的应力有可能等于原子键合力,从而导致纳米级解理裂纹在DFZ或钝化裂纹顶端形核。 By in situ stretching of Ti_3Al + Nb intermetallics under transmission electron microscope, the dislocation emission, the formation of dislocation-free region (DFZ) and the nature of the dislocation-free region (DFZ) The results show that the brittle crack can also emit a large number of dislocations and form the DFZ. Cracking may or may not be passivated after the emission dislocations. The DFZ is A highly distorted elastic zone where the stress may be equal to the atomic bonding force, resulting in the nanoscale cleavage crack nucleation at the tip of the DFZ or passivated crack.