In-situ Observation of Point Defect and Precipitate Evolvement of CLAM Steel under Electron Irradiation

The point defect and precipitate evolution of China low activation martensitic steel (CLAM) under electron beam irradiation were characterized by high voltage electron microscopy. The process was recorded in-situ on electron-sensitive films. The irradiation dose rate was 1.78 × 10−3 dpa/s and the highest dose was 2.12 dpa/s. Irradiation introduced dislocation loops into the sub-grain, which increased density when the irradiation dose was increased from 0.53 dpa to 1.59 dpa at 723 K. The precipitate, found to be an M6C type, was irradiated at 773 K at the [011] plane direction. The precipitate morphology and structure were unchanged when the irradiation dose was increased to 2.12 dpa. Compared with the irradiation at 723 K in the sub-grain, no other defects were generated at the nearby grain boundary at 773 K.