Radiation-induced amorphization behavior of thermally-aged M23C6 in F82H-BA12 steel

Abstract

To improve the understanding of the microstructural stability of F82H under fusion reactor environments, the synergistic effects of irradiation and thermal aging on the instability of M₂₃C₆ particle was investigated utilizing ion accelerator irradiation. Results show that the W-rich Laves phase growing along the grain boundaries was observed in the specimen after thermal aging at 773 K up to 10,000 hr. A bilayer contrast of the M₂₃C₆ particles consisting of an amorphous-rim and inner crystalline core was observed in the specimen irradiated by 10.5 MeV-Fe³⁺ at 623 K, but not in the specimen irradiated at 673 K, demonstrating that the critical temperature of the radiation-induced amorphization (RIA) in thermally aged M₂₃C₆ particles falls in the range of 623–673 K. These results show that thermal aging seems to play an insignificant role in the RIA behavior of M₂₃C₆ particles. Regarding the radial distribution function analysis, a relatively poor crystallinity was observed in the unirradiated thermally aged M₂₃C₆ particles, while the crystallinity was improved in the specimen irradiated at 673 K, which is ascribed to enhanced diffusion at elevated temperatures. Results indicate that the temperature-dependent point defect generation and recovery is the key factor related to the occurrence of RIA in M₂₃C₆ particles. GRAPHICAL ABSTRACT