Thick (AlTiCrNbTa)O2 high-entropy ceramic coating: Efficient fabrication and characterization

In this study, the (AlTiCrNbTa)O2 high-entropy ceramic coating was fabricated by laser cladding with squash presetting. Prior to laser cladding, the atmospheric plasma sprayed NiCoCrAlY and Al2O3-TiO2 coatings were deposited on steel substrate. The microstructure and element distribution of the (AlTiCrNbTa)O2 coating were investigated by XRD, EDS, SEM and TEM in detail. The results showed that the feedstocks with various structures were successfully transformed into the (AlTiCrNbTa)O2 high-entropy ceramic with single rutile structure through laser cladding. The (AlTiCrNbTa)O2 coating had a thick and compact structure, which consisted of mainly uniform solid solution in rutile structure and partially segregated Al2O3 with dendritic crystals structure. The (AlTiCrNbTa)O2 coating combined tightly with the Al2O3-TiO2 coating, and presented a high level of hardness (17.7 GPa) and elastic modulus (298.7 GPa).