Microstructure And Properties Of AlFeCrCoNi-Zr_x,High-entropy Alloys

High entropy alloys consists of five elements or more five elements alloying equiatomic or near equiatomic, and mixing entropy of the alloys is higher than melting entropy. Generally the HEAs is high entropy solution phase. High entropy alloys is a new research hotspot in materials science and condensed matter physics field. Therefore, based on the influence of different elements in the high entropy alloys to find high performance high entropy alloys, has important theoretical and practical significance.In this paper, the AlFeCrCoNi-Zrx system high entropy alloys was prepared by the composition design of the alloy and the vacuum arc self smelting technology, the samples were taken from the as-cast. Firstly, The phase structure and microstructure were characterized by XRD, OM, SEM-BSE and EDS. Secondly, The microhardness, compression capability and compression fracture morphology were analyzed and discussed in this paper. Meanwhile the compress performances of annealing AlFeCrCoNi-Zr0.003 and AlFeCrCoNi-Zr0.008 were also studied. Finally, the total immersion corrosion test was adopted to study the chemical corrosion resistance of AlFeCrCoNi-Zrx HEAs in 0.5M H2SO4 solution, and the PARSTAT2273 electrochemical workstation was used to study the electrochemical corrosion resistance of AlFeCrCoNi-Zrx HEAs in 0.5M H2SO4 solution and 0.5 wt.% NaCl solution. At the same time, the corrosion resistance of the FIEAs and 304 stainless steel were compared at the same conditions.The research results show that with the increasing of Zr content, the AlFeCrCoNi-Zrx HEAs shift phase structure from ordering BCC and BCC solid solution phase to ordering Leave+BCC solid solution phase. When x<0.2, the main phase is BCC phase, Zr element leads to form spinodal decomposition. When Zr is more than 0.2at, the percentage content of ordering Leave Phase increases with the increase of Zr, then BCC solution phase and ordering Leave phase nucleate and form eutectic structure.The mechanical properties of AlCoCrFeNi alloy can be increased by adding minor Zr element. The AlCoCrFeNi-Zr0.008 alloy has a yield strength of 1560MPa, fracture strength of 3513MPa and plastic strain of 36.0%. However, if the Zr content is above 0.1, both the fracture strength and plastic strain decrease significantly though the yield strength increases with the Zr content further increasing.The addition of Zr element improve the corrosion resistance of the HEAs.AlFeCrCoNi-Zrx HEAs in the corrosion resistance is superior to the 304 stainless steel in 3.5 wt.%NaCl solution. However the HEAs are poor corrosion resistance in 0.5M H2SO4, the width of the passive region AE for the HEAs is above 1000 mV.