Enhanced mechanical properties of carbon-doped FeNiMnAlCr high entropy alloy via hot-rolling

Abstract

This work demonstrates an improvement in the mechanical performance of the high entropy alloy Fe40.4Ni11.3Mn34.8Al7.5Cr6 containing 1.1 at. % carbon (CHEA) by hot-rolling followed by annealing at 1323 K. The microstructure was examined using scanning electron microscopy, electron backscatter diffraction, X-ray diffraction, and transmission electron microscopy. Room-temperature tensile tests were used to assess the alloy's mechanical properties. The presence of dense dislocation walls indicate that the alloy has not fully recrystallized and, moreover, the deformation substructure and the large fraction of Σ3 twin boundaries contribute to the high room temperature yield strength (~523 MPa). Despite the presence of substantial dislocation density, the annealed, hot-rolled CHEA displays an improvement in elongation to fracture (~33%) compared to the negligible ductility (<2%) observed for the alloy after it has been simply annealed. The present work shows that hot-rolling can produce good strength and ductility in the alloy while establishing the processing conditions necessary for the large-scale manufacture and utilization of its remarkable properties.