Effect of Ta on the Evolution of Phases and Mechanical Properties of Novel Seven Components Fe–Co–Ni–Cr–V–Al–Ta Eutectic High Entropy Alloys: Experimental Study and Numerical Simulation

Eutectic high entropy alloys (EHEAs) with seven components (Fe, Co, Ni, Cr, V, Al, and Ta) were designed and developed via vacuum arc melting route guided by the predictions obtained from ThermoCalc simulations and ANSYS Fluent. The phase evolution was predicted using CALPHAD approach which shows that when 10 at. % Ta is added, the microstructure is changed from hypoeutectic to hypereutectic with the presence of FCC and Laves phases. The simulation results explained that the time period for solidification was increased from 0.16 to 0.19 s with the addition of Ta. The solid–liquid interface advancement and the cooling curve slope at two-phase existence were linear and having different slopes by changing the Ta content. The experimental results also show the presence of eutectic mixture (L → FCC + Laves) of ductile FCC phase and hard Laves phase. The mechanical properties such as tensile strength, yield strength and microhardness of the studied alloys are increased from 828 MPa, 494 MPa, 204.67 HV to 1257 MPa, 1140.5 MPa, and 651.4 HV with the reduction of % elongation from 47.6 to 28.5% with the addition of Ta from 2.5 to 10%. The experimental results corroborate with the predicted results using thermodynamic simulation and numerical simulation by ANSYS Fluent software.