Metal matrix composite with superior ductility at 800 °C: 3D printed In718+ZrB2 by laser powder bed fusion

Abstract

We investigated the microstructure and mechanical properties of ZrB2 fortified Inconel 718 (In718+ZrB2) superalloy metal matrix composite (MMC), which was produced via Laser Powder Bed Fusion (LPBF). 2 vol% ZrB2 nano powders (below 100 nm in diameter) were decorated on the surfaces of Inconel 718 alloy powders by high-speed blender. Microstructural analysis of the as-printed specimens showed that the ZrB2 decomposed during LPBF, which promoted the formation of homogeneously distributed (Zr, Ni)-based intermetallic and (Nb, Mo, Cr)-based boride nanoparticles in the matrix. The 3D printed In718+ZrB2 has remarkably lower porosity and smaller grain size compared to 3D printed In718 fabricated under the same LPBF conditions. The mechanical performance of the as-printed and heat-treated In718+ZrB2 showed significantly higher room temperature (RT) hardness, RT yield strength (σYS), and RT ultimate tensile strength (σUTS) compared to In718. High-temperature tensile tests at 800 °C showed that In718+ZrB2 has ∼10 times higher tensile ductility with higher σYS (by 10 %) and σUTS (by 8 %) than pure In718.