Development of FeCrNi medium entropy alloys with excellent mechanical properties and corrosion resistance

ABSTRACT The development of low-cost high-entropy alloys is promising to address the demands of expanding industrial applications. In the present research, Co-free FeNiCr medium-entropy alloys were prepared by arc melting and post-processing treatments. The influence of Fe content on the microstructure, mechanical properties and corrosion resistance of these alloys were clarified. The results show that the FeNiCr medium entropy alloys exhibit a single face-centered cubic structure. These alloys consist of a multitude of fine grains and a high density of annealing twining boundary distributed at the interface of the larger grains. The Fe40Ni30Cr30 exhibits both high strength and excellent elongation. The excellent mechanical properties of FeNiCr alloys are mainly attributed to the solid solution strengthening, grain boundary strengthening, twinning induced plasticity (TWIP) effect, dimples toughening, and micropores toughening. The increase in Fe content has been observed to impede the segregation of Cr, dislocation pinning, and the nucleation of grains at the grain boundaries, leading to an increase in elongation and a reduction in strength. In addition, the electrochemical experimental results show that a stable passivation film is formed on the surface of Fe40Ni30Cr30 alloy during the corrosion process, which reduces the corrosion rate and improves the corrosion resistance of the alloy.