Uncovering the Effect of CeO[sub.2] on the Microstructure and Properties of TiAl/WC Coatings on Titanium Alloy

It remains a popular question whether rare earth oxides encourage reinforcing phases to the uniform distribution in cermet coating to improve the mechanical properties. This study applied laser cladding to prepare the TiAl/WC/CeO[sub.2] MMC cermet coatings on the TC21 alloy substrate. The effects of CeO[sub.2] content on the phase composition, microstructure formation, evolution mechanism, and properties of cermet coatings were investigated. Results show that the incorporation of CeO[sub.2] did not change the phase of composite coating, but the shape of the TiC phase has a close relation to the CeO[sub.2] content. CeO[sub.2] enhanced the fluidity of the molten pool, which further encouraged the TiC/Ti[sub.2]AlC core-shell reinforcement phase. With the increase in CeO[sub.2] content, the optimized coating contributed to homogenous microstructure distribution and fine grain size. Owing to the hard phases strengthening and dispersion strengthening effects of CeO[sub.2], the microhardness of the composite coatings was all significantly higher (almost 1.6 times) than that of the substrate. Importantly, the addition of CeO[sub.2] significantly improved the wear resistance of the composite coating. This work provides a certain reference value for the study of surface strengthening of key parts in the aerospace field.