Synergistic strengthening and toughening of eutectic C CoCr3Fe5Ni high entropy alloy
Sirui Huang, Ji-feng ZHANG, Heguo Zhu
Abstract
C x CoCr 3 Fe 5 Ni ( x =0, 0.1, 0.2 and 0.3, at.%) high entropy alloys (HEAs) were prepared via vacuum induction melting. The effects of carbon content on the microstructures and mechanical properties of the HEAs were intensively investigated. With the increase of the carbon content, the phase structure transforms from a dual-phase (FCC+BCC) to a eutectic mixture (FCC phase + M 23 C 6 carbide). Compared to CoCr 3 Fe 5 Ni base alloy, the C 0.2 CoCr 3 Fe 5 Ni eutectic HEA exhibits a significantly improved yield strength (from 307.5 to 378.9 MPa), ultimate tensile strength (from 646.5 to 837.1 MPa), and ductility (from 55.4% to 56.1%). It is shown that these comprehensive enhancements of strength and ductility result from the effect of interstitial solid solution strengthening by carbon alloying and second phase strengthening via the eutectic structure.