Nano Structure of the Rust Formed on an Iron-based Shape Memory Alloy (Fe–Mn–Si–Cr) in a High Chloride Environment

Abstract

The corrosion resistance of an Iron-based shape memory alloy (28 Mn: Fe-Mn-Si-Cr) was estimated by using wet and dry corrosion test. The structure of the rust formed on the alloy was examined via EELS (Electron Energy Loss Spectroscopy) using TEM (Transmission Electron Microscopy) analysis. The electrochemical behavior of the 28 Mn alloy was investigated via EIS (Electrochemical Impedance Spectroscopy). The 28 Mn alloy showed a much higher corrosion resistance than SM (carbon steel) in wet and dry corrosion test. In EIS measurement following the corrosion tests, the 28 Mn alloy exhibited a much larger value of corrosion resistance (Z1mHz) as compared to SM, which can be attributed to rust formation. TEM analysis indicated that the inner rust was composed of Mn-rich, Cr-Si rich and interface layer. The corrosion resistance was primarily dependent on the Cr-Si rich layer, and further supported by the Mn rich layer. It was found that the 28 Mn alloy could maintain a protective rust layer composed of effective elements in the wet and dry environment.

On the Influence of Microstructure on the Corrosion Behavior of Fe–Mn–Al–Ni Shape Memory Alloy in 5.0 wt% NaCl Solution

“…Several studies on the corrosion properties of the Fe-Mn-Si alloy have been conducted. [7][8][9][10][11][12][13][14][15][16][17][18] Although the corrosion resistance of the alloy could be improved through additions of alloying elements such as Cr, Al, Cu, Ni, and N, its commercial application is still limited due to its poor superelastic behavior at room temperature. [19] The Fe-28Ni-17Co-11.5Al-2.5Ta alloy, which was the first iron-based SMA showing a recovery strain up to 13% in a polycrystalline state, [19] shows a corrosion behavior similar to carbon steel in a 3.5 wt% NaCl solution.…”

Electrochemical polarization behavior and superelastic properties of a Fe–Mn–Al–Ni–Cr shape memory alloy

“…By adding chromium a significant improvement in the corrosion behavior was achieved. [22][23][24][25][26][27][28] As similar effects were also observed for high Mn steels (these being only used for structural applications) with a chromium content of 1-3 wt%, [29] it seems reasonable to assume that adding a chromium content of 1.5 at% (≙1.5 wt%) to the FMAN alloy could already enhance the corrosion properties. Xia et al [30] already reported a good superelastic response for single crystalline specimens in the Fe-Mn-Al-Ni-Cr alloy system with chromium contents up to 7.5 at%.…”

Superior low-cycle fatigue performance of iron-based SMA for seismic damping application

“…This may make Fe-SMA more attractive than NiTi-based SMA (also known as NiTinol [15][16][17][18][19][20][21][22][23]), especially in the civil engineering sector. In addition, Fe-SMA has good corrosion-resistance due to the existence of Mn and Cr elements [24].…”