Abstract:High-entropy alloys (HEAs) have become one of the hot topics in the field of materials science due to their unique alloy design concepts and excellent comprehensive mechanical properties. However, traditional HEAs often contain valuable Co elements and tend to be designed in equal atomic ratios, which greatly increases the alloy costs and limits their industrial applications. Based on this, a cobalt-free (Fe60Mn20Cr10Ni10)95 (AlSiC)5 medium-entropy alloy (MEA) is established. By moderately decreasing Cr and Ni while obviously increasing Fe elements, the alloy cost can be effectively reduced. Relying on the classical thermodynamic criteria and minor additions of Al, Si, and C elements, the solid-solution strengthening can be significantly improved as well as a certain carbide particle strengthening. The results reveal that the current alloy exhibits a simple face-centered-cubic (FCC) crystal structure, with a phase composition consisting of disordered FCC solid solution and ordered M23C6 carbides. Based on the cube-cube orientation relationship and almost coherent interface characteristics of FCC/M23C6, the (Fe60Mn20Cr10Ni10)95 (AlSiC)5 MEA exhibits excellent room-temperature plasticity and work-hardening ability under quasi-static conditions, with a compressive yield strength of about 360±10 MPa and a compressive strain of up to 70%. Moreover, the alloy undergoes a tensile yielding strength of 365±15 MPa, an ultimate tesnsile strength of 715±25 MPa, as well as about 40% fracture to elongation. Upon dynamic loading, the alloy exhibits a positive strain-rate sensitivity, with a dynamic yield strength of approximately 910±35 MPa, which is about 153% higher than that of quasi-static loading. Meanwhile, it still exhibits visible work hardening and even at the strain of about 40%, the alloy still does not undergo significant damage. TEM analysis shows that visible dislocation walls and cells inside the FCC matrix, as well as the interaction between M23C6 and dislocations, lead to an excellent strength-plasticity combination under quasi-static loading. The formation of deformation twins, 9R phase, stacking faults, and Lomer-Cottrell locks provides the alloy with multiple strengthening and toughening mechanisms, thus yielding the potential damage tolerance capacity upon high-speed loading.