Effect of Sn addition on microstructure, hardness and corrosion behavior of CoCrFeNiSnx high entropy alloys in chloride environment

The microstructure, hardness and corrosion behavior of CoCrFeNiSnx (x = 0, 0.1, 0.5 and 1.0) HEAs were investigated in this work. The increase of the Sn addition resulted in the improvement of hardness (reached 424.9 HV) which attributed to the increase of the Ni3Sn2 phase with higher hardness. Adding Sn with molar ratio of 0.1 promoted the pitting initiation due to the potential difference between the two phases. CoCrFeNiSn0.5 and CoCrFeNiSn1.0 exhibited enhanced corrosion resistance compared to the alloy without Sn, which ascribed to the increase in cathode area (Ni3Sn2 phase) leading to a decrease in pitting sensitivity of FCC phase.