正电子湮灭技术对材料的空位、位错等缺陷均十分灵敏,已广泛用于研究点阵缺陷及有关问题。由于塑性区内部塑性变形不均匀,故其内部缺陷密度分布亦是不均匀的,可能导致不均匀的正电子湮灭效应。本文尝试用正电子湮灭技术研究裂纹顶端塑性 Positron annihilation techniques are very sensitive to defects such as vacancies and dislocations and have been widely used to study lattice defects and related problems. Due to the non-uniform plastic deformation in the plastic zone, the internal defect density distribution is also uneven, which may lead to the uneven positron annihilation effect. This paper attempts positron annihilation technique to study the crack tip plasticity