Phase evolution of CoCrCuFeNiSix high-entropy alloys prepared by mechanical alloying and spark plasma sintering

In this study, the phase evolution and properties of CoCrCuFeNiSix (x = 0, 0.3, 0.6 and 0.9 atomic ratios) high entropy alloys prepared by powder metallurgy route is investigated. The x-ray diffraction analysis reveals the presence of mixed phases of the face-centered and body-centered cubic phase after 20 h of milling. The addition of Si (0.3, 0.6 and 0.9) favors the formation of the body-centered cubic structure during mechanical alloying. However, heating during spark plasma sintering encourages the transformation of the body-centered phases evolved after mechanical alloying to the face-centered and sigma phases. The microhardness value of CoCrCuFeNiSi0.9 high entropy alloy increased about 55% than the CoCrCuFeNi alloy. Furthermore, the enhancement in wear resistance from 0.230 km mm(-3) for CoCrCuFeNi to 0.933 km mm(-3) for CoCrCuFeNiSi0.9 alloys are observed with the Si addition. Additionally, corrosion resistance in potentiodynamic polarization measurement also enhanced with Si addition.