Irradiation accelerated lead-bismuth eutectic corrosion of the TiNbCrMoV high-entropy alloy coating: Effects of induced defects and grain growth

• The TiNbCrMoV HEA coating was irradiated with a peak damage level of 100 dpa. • Irradiation induced grain growth and the formation of dislocation loops. • Irradiation accelerated corrosion by enhancing the diffusion of Ti, V, especially Cr. • Irradiation changed the oxide composition by inducing defects and impacting the growth of oxide. In-depth understanding of the structural changes in high-entropy alloy (HEA) coating caused by irradiation is essential for comprehending the accelerated corrosion behavior. This study investigated the microstructural change of the TiNbCrMoV HEA coating under ion irradiation with the maximum fluence of 2.2 × 10 16 ions/cm 2 (∼100 dpa) and its effect on lead–bismuth eutectic (LBE) corrosion behavior. Irradiation induced the grain growth and the formation of dislocation loops. Irradiation caused surface roughening of the coating and led to the hardening of the coating without apparent embrittlement. The induced defects enhanced the diffusion of Ti, V, and especially Cr elements. Irradiation not only caused the thickening of the oxide scale, but also increased the content of Cr-oxide in the scale, such as (Cr, V) 2 O 3 . A suitable corrosion mechanism accelerated by irradiation was proposed. These findings prove that irradiation not only promoted the growth of oxides but also affected the composition of oxides through defects rather than segregation in HEA coating. This work directly links the defects caused by irradiation with the corrosion phenomenon, which is helpful for understanding the accelerated LBE corrosion behavior of HEA coating by irradiation.