Effects of Nb additions on the microstructure and mechanical property of CoCrFeNi high-entropy alloys

Effect of Al on microstructure and mechanical properties of cast CrCoNi medium-entropy alloy

“…2). Al can be partly dissolved into the as-cast CrCoNi MEA although the Al element has a very negative enthalpy of mixing and larger atomic size compared with the other constituent elements (Table 3) [25,48] . Therefore, with the increase of Al content in single FCC MEAs, the crystal lattice constant increases sharply.…”

“…A number of studies showed that elemental additions (or alloying) into alloys, including these multiprincipal-element alloys, could tailor their crystalline structures, microstructures and enhance the mechanical properties [7,[25][26][27][28][29][30][31] . For instance, He et al [7] investigated the eff ect of Al on the structure and tensile properties of CrMnFeCoNi HEA and found that the crystalline structure changes from the single FCC structure to a duplex FCC and BCC structure and then a single BCC structure when the Al concentration increases.…”

Composition Dependence on the Evolution of Nanoeutectic in CoCrFeNiNbx (0.45 ≤ x ≤ 0.65) High Entropy Alloys

“…The more negative ΔH mix , the more chance to form dual phases. Even though the total enthalpy become small but the constituent enthalpies is so large that the alloy will form two‐phase microstructure . Thus, Δ H mix is the driving force to form the eutectic microstructure as the Nb exhibits much negative Δ H mix with other alloying elements.…”

“…As an example, VNbMoTaW HEAs with single‐phase bcc SS exhibited very high strength upto 1246 MPa, but limited plasticity 1.5% under compression . On the other hand, CoCrFeNi HEAs with single‐phase FCC SS possess large ductility up to 48% under compression and low strength of 413 MPa . For practical applications, composite microstructure combining hard and soft phases may be developed to achieve a balance between strength and ductility.…”

Designing eutectic high entropy alloys of CoCrFeNiNb x

“…Meanwhile, the fracture strains of CoCrFeNiNb 0.25 and CoCrFeNiNb 0.5 alloys are both higher than 20% with fracture strengths being above 2000 MPa. Recently, Liu et al [36] reported the tensile yield strength and plastic strain of the CoCrFeNiNb x (x ≤ 0.412) alloys which show a great potential to be used as high temperature structural materials. All these data demonstrated that the CoCrFeNiNb x alloys system is very promising for structural applications.…”