Effect of Cobalt Content on Thermal, Mechanical, and Microstructural Properties of Al0.4FeCrNiCox (x = 0, 0.25, 0.5, 1.0 mol) High-Entropy Alloys

Al0.4FeCrNiCox (x = 0, 0.25, 0.5, 1.0 mol) high-entropy alloys are developed by arc melting route to investigate the effect of cobalt content on thermal, mechanical, and microstructural properties. The phase, microstructure, and chemical composition are analyzed using x-ray diffraction, transmission electron microscope, and scanning electron microscope with attached energy-dispersive x-ray spectrometer. The obtained results have shown that the Al0.4FeCrNiCox (x = 0-0.5 mol) high-entropy alloys form a simple FCC + BCC-type solid solution and Al0.4FeCrNiCox=1 HEA forms a single-phase FCC structure. The compressive yield strength, microhardness, and thermal conductivity are observed to decrease from 965.22 to 233.37 MPa, 253.6 to 155.6 HV, and from 4.87 to 2.674 W/mK, respectively, whereas the electrical resistivity is observed to increase from 150.30 to 273.74 µΩ-cm with the addition of cobalt from x = 0-1 mol. Differential scanning calorimetry analysis has indicated that the Al0.4FeCrNiCox (x = 0, 0.25, 0.5, 1.0 mol) high-entropy alloys are thermally stable up to 1000 °C.