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

Highlights: • A novel non-equiatomic (Fe35Mn10Cr20Ni35)_98.8C_1.2 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. -- Abstract: A non-equiatomic (Fe35Mn10Cr20Ni35)_98.8C_1.2 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)_98.8C_1.2 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)_98.8C_1.2 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)_98.8C_1.2 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)_98.8C_1.2 HEA in our study.