Mechanical properties of FeMnCoCr high entropy alloy alloyed with C/Si at low temperatures

Microstructural evolution and mechanical properties of FeMnCoCr high entropy alloy containing C and Si at various temperatures were investigated. The experimental results demonstrate that the microstructure of the HEAs alloy is a single-phase face-centered cubic solid solution, and the C and Si are completely dissolved in the matrix. The stacking fault energy of the alloy is about 33.96 mJ/m(2). Therefore, twins will be easy to form during the deformation process. Benefit from the synergistic effect of solid solution strengthening and twinning induced plasticity, the alloy shows a trade-off between high strength and good plasticity. Ultimate tensile strength of 757 MPa and considerable fracture ductility of 60.5% is obtained at room temperature. As the deformation temperature decreased to 227 K, the strength and plasticity are increased to 907 MPa and 69.6%, respectively. Under the low temperature, primary mechanical twins are suppressed, and more geometrically necessary dislocations and secondary nanoscale twins could be observed. The HEAs show a high work-hardening rate, which is related to dislocation slip being hindered by primary and secondary nano-twins. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Experimental results show that the microstructure of the high entropy alloy is a single-phase face-centered cubic solid solution, with carbon and silicon completely dissolved in the matrix. With decreasing temperature, the strength and plasticity of the alloy increase, and more secondary nanoscale twins are observed at low temperature.