Microstructural characterization and corrosion behaviour of AlCoCrFeNiTix high-entropy alloy coatings fabricated by laser cladding

High-entropy alloy (HEA) coatings of AlCoCrFeNiTix (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) were fabricated on AISI1045 steel by laser cladding. X-Ray diffraction (XRD) was used to investigate the phase composition of the coatings. The microstructure of coatings was analyzed using a scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-Ray diffraction (XRD) was used to investigate the phase composition of the coatings. The potentiodynamic polarization behaviour of coatings and substrate was studied. The composition of passive film on the corroded surface of the coating was identified by X-Ray photoelectron spectroscopy (XPS). The phase composition analysis showed that the coating was mainly composed of disordered body-centered cubic (BCC) solid solution phase (Fe-Cr) and ordered BCC phase (Al-Ni). The microstructure of the coatings was mainly composed of equiaxed polygonal grains, micro-nano particles of TiC and nanoparticles of Al2O3. The spinodal decomposition structure of Fe-Cr enrichment and Al-Ni-Ti enrichment was found in grains. The introduction of Ti led to passivation behavior of the coating during corrosion process. The components of the passive film were Al2O3, TiO2, Ti2O3, Cr2O3 and Cr(OH)3. The AlCoCrFeNiTi HEA coating showed the best corrosion resistance.