Effects of Cr replacing Fe on microstructure and properties of AlCoCrFeNi2.1 eutectic high entropy alloy
Jingmin Duan, Saiyang Luo, Chenglin Hou, Yong Dong, Lingbo Mao
Abstract
The AlCoCr x Fe 2-x Ni 2.1 (x=1.1, 1.2, 1.3, 1.4 and 1.5) eutectic high-entropy alloys (EHEAs) were designed and its microstructure, mechanical and corrosion properties were studied. The alloys exhibited uniform face-centered cube (FCC) / ordered body-centered cube (B2) dual-phases eutectic structure. The volume percentage of B2 phases increased from 44% to 50% with the increase of Cr contents. A large number of Cr-enriched bcc-structured nanoparticles formed in B2 phases. In addition, the compressive yield strength increases linearly from 672 MPa to 810 MPa while the fracture strength increases from 2385 MPa to 2667 MPa. The electrochemical experiment results showed that the corrosion resistance of the AlCoCr x Fe 2-x Ni 2.1 alloys increased first and then decreased when the values of x increased from 1.1 to 1.5. Among the alloys, the AlCoCr 1.2 Fe 0.8 Ni 2.1 alloy had the most outstanding corrosion resistance performance with the values of corrosion current density (I corr ) 1.06 μA/cm 2 , passivation current density (I pass ) 3.70 μA/cm 2 , pitting potential (E pit ) 457 mV SCE , corrosion potential (E corr ) -365 mV SCE , and polarization resistance ( R p ) 410.10 kΩ·cm 2 , respectively.