Engineering heterogeneous microstructure by severe warm-rolling for enhancing strength-ductility synergy in eutectic high entropy alloys

Influence of Process Parameters on Microstructure Evolution During Hot Deformation of a Eutectic High-Entropy Alloy (EHEA)

“…[27] It was argued that B2 precipitates (NiAl-type) have priority in the precipitation order because of their lower formation enthalpy during deformation, which results in an increased B2 fraction. A further increase in the B2 fraction was also observed in the EHEA when warm-rolled up to 90 pct reduction at 750°C [28] and also during subsequent annealing of the EHEA at 800°C after warm-rolling. [29] These phase transformations during warm-rolling were related to the structural features of the deformed materials including high energy interfaces and dislocations, which can effectively reduce the activation barrier to heterogeneous nucleation, thus accelerating phase transformations and decomposition.…”

Mechanical Properties and Deformation Mechanisms of Heterostructured High-Entropy and Medium-Entropy Alloys: A Review

“…Through different thermomechanical treatments, such as warm-rolling, cryo-rolling, cold-rolling, and subsequent annealing process, the heterogeneous microstructures of the AlCoCrFeNi 2.1 eutectic HEA can be further tuned to achieve superior mechanical properties, as shown in Figure 7 (Bhattacharjee et al, 2018;Shukla et al, 2018;Reddy et al, 2019;Shi et al, 2019). Warm-rolled (750 °C) AlCoCrFeNi 2.1 eutectic HEA presents a heterogeneous microstructure characterized by the mixture of the retained lamellar region of B2 and FCC with B2 phases inside the FCC lamellar and non-lamellar regions consisting of disordered FCC, precipitated B2, and Cr-rich sigma phases (Reddy et al, 2019). The heterogeneous microstructures produced by cold-rolling and cryo-rolling and subsequent annealing are quite different.…”

Microstructural evolution and mechanical characterization for the AlCoCrFeNi2.1 eutectic high‐entropy alloy under different temperatures

“…At 900–1050°C, Zhang et al 17 examined the effect of strain rate sensitivity value m , plasticity, and two distinct precipitates on recrystallization in the FCC matrix. Additionally, cold rolling, thermal mechanical treatment, or cutting‐edge synthetic methods have been used to enhance the mechanical properties of AlCoCrFeNi 2.1 EHEAs 18–24 …”

“…Additionally, by reducing the rolling temperature to the liquid nitrogen temperature, the yield strength and tensile strength of AlCoCrFeNi 2.1 are further improved while the ductility is kept at 14% 21 . Furthermore, it has been found that the heterogeneous structure produced by warm rolling at 750°C endows EHEA with good strength and ductility compared with those produced using cold rolling techniques 22,23 . In addition, the tensile mechanical behaviors and directional solidification processes of the AlCoCrFeNi 2.1 EHEAs have been studied to elucidate the deformation mechanisms 25–27 .…”

“…Additionally, cold rolling, thermal mechanical treatment, or cutting-edge synthetic methods have been used to enhance the mechanical properties of AlCoCrFeNi 2.1 EHEAs. [18][19][20][21][22][23][24] It has been demonstrated that through reasonable preparation technology and warm and/or cold rolling together with heat treatments, excellent comprehensive mechanical properties can be obtained in AlCoCrFeNi 2.1 EHEAs. 22,25,26 For example, after 90% cold rolling reduction and 1 h of annealing at a high temperature of 800 C, the EHEA presents superior strength-ductility synergy.…”