Microstructure and mechanical properties of as-cast (CuNi)100−xCox medium-entropy alloys

Microstructure and mechanical properties of non-equiatomic (CuNi)100−xCox (x=15, 20, 25 30, at.%) medium-entropy alloys (MEAs) prepared by vacuum arc-melting were investigated. Results show that all the as-cast MEAs exhibit dual face-centered cubic (fcc) solid-solution phases with identical lattice constant, showing typical dendrite structure consisting (Ni, Co)-rich phase in dendrites Cu-rich inter-dendrites. The positive enthalpy mixing among Cu Ni-Co elements is responsible for segregation Cu. With increase Co content, volume fraction increases while decreases, resulting an increment yield strength a decrement elongation MEAs. Nano-indentation test results great difference microhardness between two fcc measured value almost twofold as compared to During deformation MEAs, bears main plastic strain, whereas provides more pronounced strengthening.