Evolution of Microstructures and Properties in Al_xCrFeMn_0.8Ni_2.1 HEAs

The microstructures, compression and corrosion behaviors of the as-cast Al_xCrFeMn_0.8Ni_2.1 high-entropy alloys (0 ≤ x ≤ 2.3) were investigated in this paper. It was found that the crystal structure changed from initial dual FCC structure to mixed FCC and BCC structure, then to BCC structure as the increasing of Al content. Al_0.8CrFeMn_0.8Ni_2.1 alloy exhibited a typical spinodal structure consisting of alternating two phases microstructure. Moreover, sunflower-like microstructure was obtained in the as-cast Al_xCrFeMn_0.8Ni_2.1 alloys (1.0 ≤ x ≤ 2.0). With the increasing of Al, the macrohardness increased while the plasticity decreased in the alloys. The addition of an appropriate amount of Al could improve the compressive fracture strength of the alloys. In addition, the corrosion resistance deteriorated slightly with the increasing of Al in 1 mol/L NaCl solution.