Selective laser melted CrMnFeCoNi + 3 wt% Y2O3 high-entropy alloy matrix nanocomposite: Fabrication, microstructure and nanoindentation properties

Abstract A Y2O3-reinforced equiatomic CrMnFeCoNi high-entropy alloy (HEA) matrix nanocomposite was fabricated by high-energy attrition milling and selective laser melting (SLM) additive manufacturing. The SLM-built HEA nanocomposite possessed heterogeneous grain structures and substructures decorated with a dislocation network and exhibited a high number density of nano-sized Y2O3. The SLM-built HEA + Y2O3 nanocomposite exhibited higher nanohardness (~9.22 GPa) than other equiatomic CrMnFeCoNi HEAs produced by casting (~4.13 GPa) and SLM (~6.95 GPa). This suggested that the dispersion hardening by the Y2O3 nanoparticles enabled superior mechanical properties. This study, therefore, demonstrated that Y2O3 reinforcement can effectively improve the mechanical properties of SLM-built CrMnFeCoNi HEA matrix nanocomposites.