Microstructure and Mechanical Properties of Directionally Solidified AlCoCrCuFeNi High-entropy Alloy

Author of the article:DENG Ni, YAN Yujie, LIANG Hang, WEI Chen, HE Yixuan, WANG Jun

Author's Workplace：State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China

Key Words：high-entropy alloy; directional solidification; microstructure evolution; Cu segregation; hardness

Abstract：The effect of different drawing rates on microstructure, Cu segregation and mechanical properties of AlCoCrCuFeNi high-entropy alloy prepared by directional solidification was studied. The results show that the directionally solidified AlCoCrCuFeNi high-entropy alloy still has two simple BCC and FCC crystal structures, and its microstructure is composed of FeCoCr-rich, AlNi-rich and Cu-rich phases. With the increase of drawing rate, the solidification microstructure gradually changes from coarse dendrite to thin lamellar-dendrite, and the dendrite arm spacings decrease significantly. Under different drawing rates, the Cu-rich phase is segregated between dendrites and discontinuous zigzag distribution is formed at the boundary of FeCoCr-rich phase, and Cu-rich precipitate is formed in AlNi-rich phase. With the increase of the drawing rate, the Cu-rich precipitate changes from submicron to nanometer scale, and the concentration of Cu atoms in the Cu-rich phase decreases. The microhardness difference of different locations in the alloy decreases with the increase of drawing rate, and the average microhardness increases from 358 HV to 375 HV.