Microstructure and Properties of a Co-Free Fe50mn27ni10cr13 High Entropy Alloy

The microstructure, mechanical and corrosion properties of a cost-effective face-center cubic (fcc)-structured Co-free Fe50Mn27Ni10Cr13 high entropy alloy (HEA), which is developed here, have been studied using a comprehensive approach of ex-situ tensile tests, in-situ SEM/EBSD tensile measurements, ex-situ TEM studies, Tafel polarization, and immersion tests. After thermo-mechanical treatments, this alloy exhibits a tensile strength of 463 MPa and elongation of over 40% which are comparable to other expensive HEAs. A miniature-designed dog-bone specimen for in-situ SEM/EBSD measurements was successfully employed to study the underlying deformation mechanisms of the alloy, exhibiting the double-fiber 〈111〉 and 〈001〉 texture typical of TWIP steels. Nano-, meso- and macro-scale studies revealed that the excellent combination of strength and ductility of this newly-developed cost-effective fcc-structured HEA is originated from the formation of stacking faults and nano-twins during tensile deformation. This newly-developed alloy also exhibits good corrosion resistance in the following solutions: NaCl > NaOH > H2SO4 > HCl. The corrosion resistance was mostly found to be dependent on the amount of Mn-oxide in the passive film formed on the surface of the alloy. This work, following the non-equiatomic HEA design strategy, develops a cost-effective HEA with a good combination of mechanical with corrosion properties, which will trigger more investigations.