Microstructures and thermodynamic properties of high-entropy alloys CoCrCuFeNi

The high entropy alloys (HEAs) is a kind of innovative alloy design conception. However, seldom quantitative thermodynamics descriptions were reported in the past. In this paper, as a demonstration, the microstructures and thermodynamic properties of CoCrCuFeNi HEA were studied by combining experimental approaches with computational simulations. The CoCrCuFeNi alloy shows duplex FCC structure with Cu-lean and Cu-rich phase. With the increase of heat treatment temperature from 773 K to 1273 K, the predicted total configurational entropy changes from 6.13 to 7.83 J·mol−1·K−1, which is far less than the common-believed Boltzmann's hypothesis value (13.38 J·mol−1·K−1) due to the ordering behavior of element occupying on the sublattices. Cu atoms tend to enrich in liquid phase, which segregates as interdendritic microstructure during solidification process. The experimental results are highly consistent with the calculated results. •The site fraction and the solidifying composition were investigated quantitatively.•CoCrCuFeNi alloy shows duplex FCC structure with Cu-lean and Cu-rich phase.•Cu tend to enrich in residual liquid phase to segregates as interdendritic.•Due to the ordering behavior of elements, the mixing entropy is 7.83 kJ/(mol·atom)/K at 1273 K.