Development of a large size FCC high-entropy alloy with excellent mechanical properties

A large size 10 kg Fe40Mn40Co10Cr10 high-entropy alloy (HEA) with 3.3 at. % C-doped was prepared by electromagnetic levitation melting. The hot deformation behavior of the as-cast ingot was investigated to guide the hot forging process. Annealing was further conducted on the as-forged samples to obtain more optimized mechanical properties. The as-forged HEA had yield strength (YS) of 792 MPa, ultimate tensile strength of 1055 MPa and a satisfactory fracture elongation (EL) of 22.6%. The YS of the HEA annealed at 1050 degrees C increased from 393 MPa to 512 MPa and EL from 26.5% to 55.3% in comparison with the as-cast HEA. It is suggested that the enhanced yield strength of the as annealed HEA was attributed to carbon interstitial solid solution strengthening, grain refining and precipitation of tiny carbides, and the improvement of ductility was due to the elimination of cast defects and twinning-induced plasticity. This work paved the way for the application of HEA as high performance structure materials.