Design Multicomponent Eutectic Alloys in the Co–Cr–Fe–Ni–Nb System Using Simple Mixing Method

Herein, a series of ternary to quinary eutectic alloys in the Co–Cr–Fe–Ni–Nb alloy system are designed/located following the simple mixing strategy based on the Ni–Nb, Co–Nb, Cr–Nb, Fe–Nb binary phase diagrams. The designed NiFeNb0.35, CoFeNiNb0.5, CoCrFeNiNb0.45 eutectic alloys are prepared. The phase formation, microstructure evolution, and mechanical properties of the eutectic alloys are studied. All of these designed eutectic alloys are composed of Nb‐rich intermetallic compound phase and Nb‐poor face‐centered cubic (Fcc) phase. However, these eutectic alloys show different eutectic morphology. The FeNiNb0.35 alloy exhibits a compact seaweed eutectic‐dendritic pattern. The CoFeNiNb0.5 alloy shows dendritic eutectic morphology. The CoCrFeNiNb0.45 alloy exhibits eutectic cell morphology. Mechanical tests results indicate that the NiFeNb0.35, CoFeNiNb0.5, CoCrFeNiNb0.45 alloys have higher Vickers hardness and strength. Wherein, the CoCrFeNiNb0.45 alloy is found to combine the best comprehensive mechanical properties with yield strength of 1316 MPa, fracture strength of 2339 MPa, compressive strain of 24.2%, fracture toughness of 18.4 MPa m1/2, and Vickers hardness of 511 HV. The solid solution strengthening of the FCC phase and the hard intermetallic phase strengthening are the major strength mechanism in this eutectic alloys.