MIT News May 19, 2022
An international team of researchers (USA – MIT, Turkey) used additive manufacturing (AM) of a nickel superalloy metallic matrix composite (Ni-MMC) using laser powder bed fusion (LPBF). They prepared nanoceramic-containing composite powders by high-speed blender decluttering and ball milling of as-received SiC nanowires (2 vol%) and Inconel 718 alloy powders which produced a homogeneous decoration of SiC on the surfaces of Inconel particles. Analysing the as-printed specimens revealed the dissolution of SiC nanowires during laser melting, leading to the in-situ formation of Nb- and Ti-based silicide and carbide nanoparticles. The in-situ formed nanoparticles resulted in a more desirable solidification microstructure of the AM Inconel 718 with fewer printing defects (cracks and pores) and slightly refined grain sizes. Mechanical characterization of the as-printed Ni-MMCs revealed notable increases in hardness, yield strength and ultimate tensile strength compared to the reference samples without SiC addition. After heat treatment, the same composite samples displayed a 10% higher tensile strength compared to identically treated unreinforced material while maintaining ∼14% total tensile elongation. According to the researchers the in-situ precipitate formation presents a simple and effective method for strengthening additively manufactured high-temperature materials that could be used in the increasingly harsh environments in energy and propulsion applications…read more. TECHNICAL ARTICLEÂ
Graphical abstract. Credit: Additive Manufacturing, Volume 67, 5 April 2023, 103478Â