Microstructure evolution mechanism of WB-doped Fe-based amorphous composite coating under proton beam irradiation

Fe-based amorphous coatings exhibit exceptional irradiation resistance attributed to their distinct topologically disordered structure, rendering them highly attractive for advanced nuclear energy applications. The incorporation of WB secondary phase doping can notably alter the coating to enhance its operational safety. In this investigation, three different Fe-based composite coatings, with varying WB doping levels of 5 %, 10 %, and 15 % were fabricated through the High-Velocity Oxy-Fuel (HVOF) spraying technique. Irradiation tests were conducted at room temperature utilizing a proton beam with an energy of 1.52 MeV to simulate neutron irradiation environment in a nuclear reactor. The microstructure evolution before and after irradiation was systematically investigated with XRD, SEM, and TEM techniques. The results demonstrated that proton irradiation induced free volume, crystallization and H bubbles evolution. The doping of WB diminished the proton implantation dose threshold for segregation in irradiation plateaus while enhancing the growth of precipitates around the damage zone by inducing the production of M23C6 carbides and, at the same time, increasing the probability of H bubble nucleation and growth. These findings provide insights for iterative updates in Fe-based amorphous materials, informing their further development and application. •WB doping promotes M23(C, B)6 precipitation from Fe-based amorphous coatings.•Irradiation-induced FCC-Fe/Cr phase transition in amorphous coatings.•Free volume is the nucleation site for phase transition induction.•WB doping affects the phase transition and H bubble evolution.