Tensile deformation behavior and strengthening mechanism of a Fe2.5Ni2.5CrAl multi-principal element alloy

The microstructure and tensile deformation behavior of a Fe2.5Ni2.5CrAl multi-principal element alloy (MPEA) were investigated. The combined effect of the soft FCC phase and the hard BCC + B2 microcon-stituent resulted in a best-in-class strength-ductility combination. The stress-strain relationship obtained from nano-indentation tests agrees well with the tensile stress-strain curves. The fracture sur-face of Fe2.5Ni2.5CrAl MPEAs indicates the ductile fracture. Cracks tend to form at the interfaces of the FCC/ BCC phases and expand along the voids by plastic deformation. Both dislocations and deformation twin-ning were responsible for the excellent properties. Second phase strengthening resulted in the largest strength increment. MD simulations revealed the formation of the HCP structure and stacking faults. Shockley dislocations were the key factor in the deformation behavior. Our study has shown best-in -class strength-ductility combination in a commercially relevant multi principal element alloy, the results are promising for several industrial applications.& COPY; 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The microstructure and tensile deformation behavior of a Fe2.5Ni2.5CrAl multi-principal element alloy (MPEA) were studied. The combination of soft FCC phase and hard BCC + B2 microconstituent resulted in high strength and ductility. The stress-strain relationship obtained from nano-indentation tests matched well with the tensile stress-strain curves. The fracture surface indicated ductile fracture with cracks forming at the interfaces and expanding along the voids. The presence of dislocations and deformation twinning contributed to the excellent properties. Second phase strengthening played a significant role in increasing strength. MD simulations revealed the formation of HCP structure and stacking faults, with Shockley dislocations being the key factor in deformation behavior. This study demonstrates the potential of the Fe2.5Ni2.5CrAl MPEA for various industrial applications with its superior strength-ductility combination.