Effect of Ti and C additions on the microstructure and mechanical properties of the FeCoCrNiMn high-entropy alloy

To improve the yield strength of an FeCoCrNiMn high-entropy alloy (HEA), elemental Ti and C were doped into the alloy. Subsequently, an in situ synthesized carbides particle-strengthened HEA matrix composite was prepared by mechanical alloying (MA), followed by a vacuum hot-pressing sintering (VHPS) method. The TiC nanoparticles were distributed along the grain boundaries. The microstructure of the alloy contained a face-centered cubic (FCC) solid solution as the matrix phase and small amounts of TiC, M23C6 and M7C3 (where M = Cr, Mn, Fe) carbides. The addition of elemental Ti and C significantly improved the room-temperature compressive yield strength of the FeCoCrNiMn HEA from 774 MPa to 1445 MPa (an 86.7% increase), accompanied by a decrease in the compressive strength and plasticity. Grain boundary strengthening and precipitation strengthening are the main strengthening mechanisms of the alloy doping with elemental Ti and C.