Microstructure and mechanical properties of supersonic plasma sprayed Mo-based coating reinforced by Re

Abstract Molybdenum zirconium titanium (Mo-Zr-Ti) and molybdenum zirconium titanium rhenium (Mo-Zr-Ti-Re) composite coatings were deposited by supersonic plasma spraying technology. Scanning electron microscopy (SEM), energy dispersive microanalysis (EDS), transmission electron microscope (TEM) and indentation test were used to investigate the microstructure, phase composition and mechanical properties of the coatings. SEM and EDS results showed that the Mo-Zr-Ti-Re coating was composed of bright and grey areas corresponding to Re-rich and Re-poor microstructure areas, respectively. TEM indicated that the Mo-Re alloy phase and Ti-rich areas were formed in the composite coating. Indentation experiments found that radial and edge cracks were extended at the indentation of the two kinds of coatings. The hardness, elastic modulus, and fracture toughness of the Mo-Zr-Ti-Re coating were improved by 21%, 9%, and 30%, respectively, in comparison with those of the Mo-Zr-Ti coating. The observed toughening mechanisms were crack branches and crack deflection, which can effectively inhibit crack propagation.