Characterization of the corrosion behavior of FeCoCrNiAl high entropy alloy

Full text: Most conventional alloys is composed of one or two principal elements, where different kinds of alloying elements are incorporated acting like properties modifiers [1]. High entropy alloys (HEA) are composed of four or more principal elements with an equiatomic composition, shown special properties as high mechanical and wear resistance, hardness, dimensional stability and corrosion resistance [2]. In the present work, a high entropy alloy composed of FeCoCrNiAl was processed by means of arc furnace melting and immersed in 3.5% NaCl solution for 1h, 4h, 8h and 24h. The aim was to investigate its electrochemical behavior. The morphology of the alloy was evaluated by scanning electron microscopy (SEM). The passive film composition was evaluated by X-ray Photoelectron Spectroscopy (XPS).The chemical composition was evaluated by EDS (Energy Dispersive X-ray Spectrometry). The characterization of the electrochemical behavior was made by electrochemical impedance spectroscopy (EIS). The results showed a microstructure formed by dendritic solid solution phases and inter dendritic phases. The corrosion resistance was affected by the immersion time. The results are discussed based on the correlation between the chemical composition of the alloy surface and its electrochemical response. References: [1] Huang, K.-H. and J. Yeh, A study on the multicomponent alloy systems containing equal-mole elements. Hsinchu: National Tsing Hua University, 1996. [2] Tsai, M.-H. and J.-W. Yeh, High-entropy alloys: a critical review. Materials Research Letters, 2014. 2(3): p. 107-123. (author)