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, has 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: NaCI > NaOH > H2SO4 > HCI. 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. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The research focused on the microstructure, mechanical, and corrosion properties of a cost-effective HEA alloy, demonstrating excellent strength and ductility due to the formation of stacking faults and nano-twins during tensile deformation. The alloy also exhibited good corrosion resistance, mainly dependent on the amount of Mn-oxide in the passive film.