Effect of alloying elements on microstructure and properties of multiprincipal elements high-entropy alloys

Ten high-entropy alloys are prepared by an arc furnace. The microstructure and the properties of the alloys are investigated. FeNiCrCuCo and FeNiCrCuMo alloys consist of a single FCC solid solution. When Cu or Co in the alloys is substituted by Al, the microstructures of the alloys change to that of BCC solid solution or that of a BCC+ FCC solid solution. The results show that Cu with a FCC structure promotes the formation of a FCC solid solution. Although Al has a FCC structure, it does not help the formation of a FCC solid solution. In addition, when Zr is added into the alloys, complicated compounds are present due to the stronger compound formation tendency between Zr and other components. It is found that the hardness of alloys with a BCC structure is higher than that of the alloys with a FCC structure. The hardness of the alloys increases with increasing of Al content. When complicated compounds are formed, the hardness increases further. The highest hardness reaches 566 HV due to the strengthening of the second phase precipitation. (C) 2008 Elsevier B.V. All rights reserved.