Development of strong and ductile metastable face-centered cubic single-phase high-entropy alloys

High-Temperature Deformation Behaviors of the C-Doped and N-Doped High Entropy Alloys

“…Similarly, the SFE and the stability of the FCC phase decrease when the Co concentration increases, but this also decreases the Fe and Ni concentrations; meanwhile, the elastic modulus, anisotropy, and lattice friction force increased as well [8]. Further, a minor addition of Mo could increase the lattice constant and decrease the SFE and elastic modulus [10]. Based on these findings, a series of novel high-performance Co-rich non-equiatomic HEAs and MEAs were developed and exhibit tensile properties that are superior to other reported FCC single-phase HEAs or MEAs.…”

“…This exceptional mechanical performance is attributed to its low stacking fault energy (SFE, 25-30 mJ/m 2 ) [6]. The SFE plays a crucially important role in the regulation of plastic deformation behavior and mechanical performance: a high SFE value (>45 mJ/m 2 ) results in dislocation slip and the formation of dislocation cells during deformation; an intermediate SFE value mJ/m 2 ) promotes the activation of deformation twinning, which increases strength and ductility in a process known as twinning-induced plasticity (TWIP); a low SFE value (<15 mJ/m 2 ) stimulates the strain-induced displacive phase transformation from an FCC structure to an HCP (hexagonal close-packed) structure, which elevates the strength and ductility because of the transformation-induced plasticity (TRIP) effect [7][8][9][10][11][12]. For this reason, the Cantor HEA exhibits high strength and large ductility with the assistance of the TWIP effect.…”

“…As mentioned above, it is reasonable to optimize the mechanical properties of HEAs and MEAs by regulating the SFE. For this purpose, guidelines for regulating SFE in the Cantor, CoCrFeNi, and CoCrNi alloys have been recently proposed and use the combinatorial methods of first-principle calculations, thermodynamic predictions, and experimental verifications [8][9][10]. The results showed that an increase in the content of Co and Cr at the expense of Mn, Ni, and Fe in the Cantor alloy significantly reduces the SFE [9].…”

Hot Deformation and Dynamic Recrystallization Behavior of CoCrNi and (CoCrNi)94Ti3Al3 Medium Entropy Alloys

“…Among those HEAs, the face-centered cubic (fcc) single-phase CoCrFeMnNi and CoCrFeNi alloys are the most widely investigated, which exhibit exceptional mechanical properties at both ambient and cryogenic temperatures [2][3][4][5]. To date, much effort was devoted to improving mechanical performance, where meta-stabilization is one of the most widely utilized methods [6][7][8][9]. The stacking fault energy (SFE) will be decreased along with the reduction of fcc-phase stability, which determines the plastic behavior and mechanical properties.…”

“…An intermediate SFE mJ/m 2 ) promotes the formation of mechanical twinning [10], whereas a low SFE (<15 mJ/m 2 ) leads to the strain-induced martensitic transformation [11,12]. Both of them contribute to the enhancement of mechanical properties by twinning-induced plasticity effect and transformation induced plasticity effect [7][8][9][10][11][12].…”