Recrystallization of a novel two-phase FeNiMnAlCr high entropy alloy

Abstract

Cold rolling followed by annealing was performed on the as-cast, two-phase (f.c.c. + B2), lamellar-structured high entropy alloy Fe 28.

Simultaneous Strength-Ductility Enhancement of a Nano-Lamellar AlCoCrFeNi2.1 Eutectic High Entropy Alloy by Cryo-Rolling and Annealing

“…The present EHEA has much higher YS (and UTS) that the other two HEAs, namely Al 0.5 CoCrCuFeNi and Fe 40 Mn 27 Ni 26 Co 5 Cr 2 which fall above this line. Evidently, the present cryo-rolled and annealed EHEA is much superior to other HEAs 39 – 43 as a structural material possessing ultrahigh strength and ductility.

Figure 6 Strength-elongation plot of selected HEAs.

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“…The relative hardness difference between the two phases (ΔH cold ) would result in the L1 2 phase being deformed more easily than the B2 phase at the initial stages of deformation. However, with increasing deformation at room temperatures, the B2 phase would eventually start deforming 35 , 39 , 45 . In contrast, at the cryo-rolling temperature, the hardness or the flow stress of the B2 phase is expected to increase significantly, while the hardness of the L1 2 would be much less affected.…”

Ultrafine-Grained AlCoCrFeNi2.1Eutectic High-Entropy Alloy

“…[22,23] This has been attributed to their sluggish diffusion behavior that suppresses grain growth. [21] In addition to the sluggish diffusion effect, the finely fragmented microstructure of the present EHEA after cold-rolling should provide high density of potential nucleation sites for recrystallization in the subsequent annealing stage.…”

“…This is in contrast to FeNiMnAlCr alloy having lamellar microstructure, where strength after annealing is lower than the as-cast alloy due to structural coarsening. [23] The increase in strength after annealing as compared to the as-cast material is likely due to the increased fraction of the harder B2 phase [23] and equiaxed morphology of the UFG structure. The YS of this alloy in the annealed condition ( ∼ 1100 MPa) is evidently much higher than other cold-rolled and annealed lamellar alloys such as FeNiMnAlCr ( ∼ 600 MPa) [23] and Al 0.5 CrCuFeNi 2 ( ∼ 950 MPa).…”

“…[23] The increase in strength after annealing as compared to the as-cast material is likely due to the increased fraction of the harder B2 phase [23] and equiaxed morphology of the UFG structure. The YS of this alloy in the annealed condition ( ∼ 1100 MPa) is evidently much higher than other cold-rolled and annealed lamellar alloys such as FeNiMnAlCr ( ∼ 600 MPa) [23] and Al 0.5 CrCuFeNi 2 ( ∼ 950 MPa). [18] The other interesting feature of the annealed UFG EHEA, that is, discontinuous yielding has been reported in various kinds of UFG materials, [26][27][28][29] although the mechanism is yet to be clarified fully.…”