Surface modification of CoCrAlY coating by high-current pulsed electron beam treatment under the "evaporation" mode

Highlights: •CoCrAlY coating irradiated by pulsed electron beam was investigated. •Coarse surface was melted and structural defects were sealed after irradiation. •Nano-scale bubbles and alumina particulates were dispersed on the surface. •The feature and composition modification were induced due to the evaporation mode. -- Abstract: High current pulsed electron beam (HCPEB) was conducted on a CoCrAlY coating. The microstructure evolution and surface morphology of the coatings were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), and three-dimensional laser scanning microscope (LSM), respectively. XRD result shows that Al₂O₃ and YAlO₃ phases were recorded in the irradiated coatings. Co-based oxides which originally existed in the initial samples disappeared and the content of CoAl peaks significantly reduced as the pulses increased. Microstructure observations reveal that the coarse surface was melted and the structural defects inherent in the initial coatings were sealed after HCPEB irradiation. Surface features such as wavy aspects with abundant particulates as well as nano-scale bubbles and chemistry modifications were discussed as the consequence of the evaporation–condensation process