Microstructure and properties of FeCoCrNiMoSix high-entropy alloys fabricated by spark plasma sintering

• FeCoCrNiMoSi x (x = 0.5, 1.0, 1.5) HEAs were fabricated by SPS under 1150 °C. • Hardness of FeCoCrNiMoSi 1.5 reached 1186 HV. • High corrosion potential of Si makes FeCoCrNiMoSi 1.5 exhibits great corrosion resistance. • The oxidation properties FeCoCrNiMoSi 0.5 were greater than that of other FeCoCrNiMo HEAs. • Different properties can be obtained through controlling Si content. FeCoCrNiMoSi x (x = 0.5, 1.0, 1.5) high-entropy alloys (HEAs) were successfully fabricated by spark plasma sintering (SPS). The microstructure, tribological properties, oxidation behaviors and corrosion resistance of the HEAs were systematically investigated. The experimental results showed that the microstructure mainly consisted of Fe-rich face-centered-cubic (FCC) phase, Mo-rich FCC phase solid solution and various Si-rich intermetallics, where the elevated Si content coarsened the primary Mo-rich phase into dendritic eventually. These Mo-rich dendrites possessed strong covalent-dominant atomic bonds that enhanced the microhardness (from 725 to 1186 HV) and wear resistance. The FeCoCrNiMoSi 0.5 HEA exhibited an outstanding combination of relatively high wear resistance and the strongest oxidation resistance under 800 °C among the three alloy compositions. The corrosion resistance of HEAs showed an increasing trend with the elevated Si content, and FeCoCrNiMoSi 1.5 presented the best performance.