Effect of Al content on the microstructure and properties of CoCrCuFeNiMoAlx high entropy alloy

A new multi-principal Co-Cr-Cu-Fe-Ni-Mo-Al high entropy alloy with good mechanical properties and corrosion resistance was prepared. For the phenomenon of Cu segregation, we report a strategy to tailor the existing form of Cu in HEA from undesired large-scale segregation to uniform distribution in the solid solution phase. The effects of the Al content on the microstructure, mechanical properties and corrosion behavior of CoCrCuFeNiMoAlx (x = 0, 0.32, 0.67, and 1.0) alloys were studied. The results show that when Al content is low, Cu segregation phenomenon is serious, and the microstructure of the alloy is FCC structure and a little BCC structure. With the increase of Al content, the microstructure is gradually transformed into BCC structure, and the Cu segregation phenomenon is improved. In addition, with the increase of Al content, the mechanical properties of the alloy are improved to some extent. According to the experimental results, the hardness increased by 30.4 %and the compressive strength increases by 22.9 %. Moreover, an increasing Al content had a positive influence on the corrosion resistance of the alloy, increased corrosion potential of the alloy and reduced corrosion current.