Investigation of the effect of titanium addition to FeCoCuNiMn high entropy alloy on electrochemical properties

In this study, it is aimed to investigate the properties of FeCoCuNiMn Ti(0-0.5) high entropy alloys. In this context, FeCoCuNiMnTi(0-0.5) alloys were successfully produced by vacuum arc melting method. With the addition of 0.1% titanium element atomically, the change in microstructure, the effect of titanium element on corrosion and phase structures were investigated. While the CoCuFeNiMn alloy has a homogeneous chemical composition in the dendritic and interdendritic regions, titanium-rich regions were formed in the interdendritic regions with the addition of Ti to CoCuFeNiMn. Ecorr and icorr values for CoCuFeNiMn alloy were -0.322 V (vs. Ag/AgCl) and 6.30 × 10−7 A.cm-2, respectively. Measured as -0.982 V and 1.16 × 10−3 A.cm-2 for CoCuFeNiMnTi0.5 alloy, respectively. It was understood from the Nyquist and phase angle graphs that 0.3% Ti ratio is the critical value for the formation of the passive TiO2 layer on the alloy surface. It was determined that the most important effect of Ti addition on the corrosion properties of CoCuFeNiMn alloy was the conversion of pitting corrosion type to galvanic corrosion. It was observed that the corrosion rate increased as the Ti addition increased. The best corrosion resistance was found in FeCoCuNiMn alloy without Ti addition.