Carbon-alloyed Fe35Mn10Cr20Ni35 high entropy alloy synthesized by mechanical alloying plus spark plasma sintering

A non-equiatomic (Fe35Mn10Cr20Ni35)98.8C1.2 high entropy alloy (HEA) was synthesized by mechanical alloying plus spark plasma sintering. Microstructure was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The mechanical behaviors were measured by Vickers hardness, nano-indentation and compression tests. After 75 h’ mechanical alloying, (Fe35Mn10Cr20Ni35)98.8C1.2 HEA powder with simple FCC structure was prepared. M7C3-type carbide particles with a size of about 100–200 nm are observed to precipitate from FCC-matrix during spark plasma sintering process. In (Fe35Mn10Cr20Ni35)98.8C1.2 HEA synthesized by mechanical alloying plus spark plasma sintering routine, the density of dislocations is much higher than that in Fe35Mn10Cr20Ni35 HEA prepared by arc-melting method, and the grain size is much smaller. Combined effects of dislocation hardening, fine grain strengthening and precipitation hardening of second phase particles make (Fe35Mn10Cr20Ni35)98.8C1.2 HEA possess much higher compression yield strength than Fe35Mn10Cr20Ni35 HEA prepared by arc-melting routine (1200 MPa–180 MPa), especially the former two effects. The formation of dislocation cells and twins during plastic deformation is thought to support to the high plasticity of (Fe35Mn10Cr20Ni35)98.8C1.2 HEA in our study. •A novel non-equiatomic (Fe35Mn10Cr20Ni35)98.8C1.2 HEA is synthesized by mechanical alloying and spark plasma sintering.•This HEA has excellent compression deformation ability, and possesses very outstanding compression strain.•Combined effects of dislocation, fine-grain and precipitation make it possess much higher compression yield strength.•The formation of dislocation cells and twins during plastic deformation is responsible for its high plasticity.