Effect of Ce addition on microstructure and hardness of (Ni₂CoFe)₈₆Ti₈Al₆ high entropy alloy

Abstract The effects of different Ce contents on the microstructure and hardness of (Ni2CoFe)86-xTi8Al6Cex (x = 0, 0.1, 0.3, 0.5, 0.7, 1.0 molar ratio) high entropy alloys were systematically studied. The results show that the addition of Ce promotes the precipitation of new FCC and BCC phases. The precipitates were promoted by Ce, and the grains and structures were refined by Ce. With the gradual increase of Ce content, the hardness gradually increases. The microhardness (HV) of (Ni2CoFe)85Ti8Al6Ce HEA is 458.6. The increase of precipitate volume fraction and fine grain strengthening are the main reasons for the increase of hardness.