本文对材料断裂研究中的裂纹尖端形变行为,特别是裂纹尖端无位错区的研究作了简要评述。其中包括:一些薄膜金属,如 Al,Cu,Nb,Fe,W 和 Mo 等,裂纹尖端在变形时的位错发射和无位错区存在的实验事实;裂纹尖端位错的屏蔽与反屏蔽概念的引进;材料断裂研究中无位错区模型的引进和描述;延-脆断裂转变的判据。 In this paper, the fracture tip deformation behavior in the study of material fracture, especially the study of dislocation-free zone at crack tip, is briefly reviewed. These include experimental facts about the presence of dislocation emission and dislocation-free regions in the presence of thin film metals, such as Al, Cu, Nb, Fe, W and Mo, at crack tip deformation; the concept of masking and anti-masking of crack tip dislocations ; The introduction and description of the dislocation-free region model in the study of material fracture; and the criterion for the transformation of ductile-brittle fracture.