Inconel 718 alloy reinforced with nano-sized WC particles and graphene nanoplatelets: Microstructure, wear resistance and electrochemical properties

Abstract

The coarse columnar grain structure of additively manufactured metals diminishes material performance, hence the transition from columnar grains to equiaxed grains is extensively investigated. The microstructure of composite materials and the properties of Inconel 718 are positively influenced by both nano-sized tungsten carbide (nano-WC) and graphene nanoplatelets (GNPs), which act as reinforcing phases. The study employs directed energy deposition (DED) technology for the fabrication of Nano WC/GNPS-IN718 composite materials. Th emicrostructure, wear resistance, and corrosion resistance properties of both Inconel 718 and its composite materials were systemically investigated. The findings discover the microstructure of the composite material consists of γ/M7C3 phases with precipitation of carbides such as (Nb,Ti)C. Utilizing nano WC and graphene as lubricants, and carbides like (Nb,Ti)C as strengthening phases, the composite material exhibits a grain size refinement of approximately 3.36 % compared to IN718. The grain orientation in the XOY plane predominantly aligns along the <001> direction. The Nano WC/GNPS-IN718 composite material exhibited a 1.264-fold increase in average microhardness compared to the IN718 alloy. Notably, the friction coefficient and wear rate were only 77 % and 18.75 %, respectively, of those observed in the IN718 alloy. Furthermore, the corrosion current density of the Nano WC/GNPS-IN718 composite material was 30.8 % of that observed in IN718, with a polarization resistance 4.08 times higher than that of IN718.