Microstructure and Mechanical Properties of Inconel 718 / Yttria-Stabilized Zirconia (YSZ) Metal Matrix Composite Coating Produced by Laser Directed Energy Deposition Technique

Metal matrix composites (MMCs) possess a favorable combinations of mechanical, thermal, physical and metallurgical properties which can be engineered by controlling composition, concentration, size and dispersion of the ceramic particles in the metallic matrix. Laser directed energy deposition (DED) technique has the ability to fabricate MMC coatings with good mechanical properties and sound metallurgical bonding. Owing to those beneficial aspects, LDED has become one of the most important fabrication techniques of MMC. Despite of immense applications of MMCs, there has been very limited research work reported in the literature regarding the development of MMC coatings. In the present study, Inconel 718/Yttria-stabilized zirconia (YSZ) MMC coating is deposited on the H13 steel substrate via laser DED process. This MMC can find its application as ultra-high strength thermal barrier coatings in aerospace, power generation, defense equipment manufacturing and die/mold making industries. Three types of MMCs, Inconel-1 wt. % YSZ, Inconel-2 wt. % YSZ, and Inconel-3 wt. % YSZ are fabricated in order to assess the effect of YSZ weight percentage on the microstructure and mechanical properties (i.e., micro-hardness and porosity) of the MMC. Based on the mechanical properties and microstructural study, the optimum amount of YSZ in MMC is determined and it is observed that Inconel-1 wt. % YSZ composite coating exhibits better mechanical (i.e., hardness = 495 ± 7 HV, and porosity = 4 %) and metallurgical properties.