Seven FeCrAlY-Al₂O₃ nanoceramic composite coatings are deposited on F/M steel via plasma spraying and laser remelting. A systematic investigation is conducted to examine the dependence of microstructure, mechanical properties, and lead–bismuth eutectic (LBE) corrosion resistance on the nano-Al₂O₃ addition and different Cr and Al contents. With the increase in Al content in FeCrAlY, gradual refinement of the coating grains occurs. The addition of nano-Al₂O₃ promotes the elemental segregation and precipitation of the second phase. The nano-Al₂O₃ notably enhances the mechanical properties of the coatings that are primarily attributed to second-phase and fine-grain strengthening. After LBE corrosion tests, intergranular corrosion morphology could be observed, where the contents of Cr and Al significantly influence the corrosion behavior of the coatings at varying temperatures.

The structural evolution of Cr-coated Zr-4 after irradiation was studied via in situ TEM in the temperature range from room temperature to 1000 °C. The results show that the krypton bubbles appeared at ~700 °C, and their size increased with increasing temperatures. The grain size and shape of the irradiated Zr-4 substrate changed with increasing temperature, and finally, columnar crystals appeared, which was related to the compressive stress induced via irradiation. The Cr₂Zr C14 phases formed at both the interface and the substrate at 700 °C and 1000 °C. Moreover, the accelerated failure process of irradiated Cr coating at high temperatures was observed via in situ TEM analysis.