Effects of irradiation dose and temperature on dislocation loop evolution of Al-forming austenitic stainless steel with In-situ TEM observation

Abstract

The Al-forming austenitic (AFA) stainless steel are regarded as an excellent potential candidate for next generation nuclear reactor. But the irradiation effects on its microstructural and mechanical properties are still unclear. In this paper, irradiations with a 400KeV Fe+ accelerator at room temperature (RT), 673 K and 773 K were produced. Self-ions were selected to study the evolution of irradiated-induced dislocation loops singly avoiding an interaction with other irradiation defects. The loop nature, average size and density were affected obviously by irradiation dose and temperature. Two sets of dislocation loops were identified to b = 1/2<110< and b = 1/3<111< . Interestingly, b = 1/3<111< does not occupy the majority like other stainless steels, but their proportions and size enhanced with temperature and dose. The evolution of microstructure was illustrated, dislocation loops nucleate, grow, merge, and finally form dislocation network structure. The average size increased with irradiation parameters. While the number density is a little different, which increased with irradiation dose but showed an opposite tendency with temperature. The dislocation network structure would limit the growth of loops and reduce the density. The yield strength caused by the irradiation-induced dislocation loops would be further deepened mainly since the dislocation loop's average size plays a vital role.