Microstructure and corrosion behavior of AlCrTiV-X (X = Cu, Mo, CuMo) high-entropy alloy films in 3.5 wt.% NaCl solution

In this work, the microstructure and corrosion behavior in 3.5 wt.% NaCl solution, of AlCrTiV-based high-entropy alloy (HEA) films with Cu, Mo, and Cu/Mo, prepared by DC magnetron sputtering, are investigated. The results indicate that all these HEA films are composed of a single BCC phase, but with different lattice constant and different surface topographies. The AlCrTiV, AlCrTiVCu, and AlCrTiVMo HEA films display the surface with tetrahedral nanoparticles, but the AlCrTiVCuMo HEA film shows the surface with near-spherical nanoparticles. Among these HEA films, the AlCrTiVCu HEA film shows the best corrosion-resistance, owing to the dense surface morphology and relatively small surface feature size, but the AlCrTiVCuMo HEA film with the minimum surface feature size has the worst corrosion-resistance, which is due to the obvious holes on its surface and the relatively low content of Al and Cr elements. However, these four HEA films all show a better corrosion-resistance than 304SS, explained by the formation of stable oxides comprising of Al2O3, Cr2O3, etc.