Mechanical properties and liquid lead–bismuth eutectic corrosion behavior of FeCrAlTiSi amorphous high entropy alloy coatings using magnetron sputtering

In this work, amorphous FeCrAlTiSi high entropy alloy coatings (HEACs) were designed and fabricated via magnetron sputtering technique under different sputtering powers. Their microstructure, mechanical properties and LBE corrosion behavior were investigated through SEM, EDX, TEM, XRD and XPS. Results demonstrate that with the sputtering power increasing from 200 W to 500 W, the hardness and Young’s modulus increased at first and then decreased, reaching the maximum of 27 GPa and 356 GPa, respectively, at 300 W. Furthermore, this coating demonstrated excellent corrosion resistance to liquid lead–bismuth eutectic (LBE), with a lamellar oxide layer formed on its surface upon 500 h of exposure to LBE at 550 °C, which consisted of, from outside to inside, discrete Fe 3 O 4 layer, FeCr 2 O 4 layer, Al-rich oxide layer and inner mixed (Al, Cr, Ti, Si)-O layer, subsequently, without the occurrence of lead–bismuth penetration into the substrate. Correspondingly, a novel corrosion mechanism was established. These results indicate that the FeCrAlTiSi HEA coatings are promising protective coatings used in Gen-IV lead-cooled fast reactor.