Microstructure and electrochemical corrosion behavior of Cr–Ni–Fe alloy deposits electroplated in the presence of trivalent Cr ions

Cr–Ni–Fe alloy deposits containing different Cr, Ni and Fe contents were created by varying the electroplating current density in an eco-friendly trivalent Cr-based bath with Ni²⁺ and Fe²⁺ ions. The Cr content of the Cr–Ni–Fe alloy deposits increased from 14 to 75 wt.% when the electroplating current density changed from 15 to 25 A/dm². The mapping result obtained with a scanning electron microscope showed that a uniform ternary Cr–Ni–Fe alloy deposit could be obtained from the proposed bath, and X-ray diffraction results indicated the Fe-based alloy electroplated at 15 A/dm² was crystalline, whereas the Cr-based alloy deposits electroplated at a high current density had an amorphous structure. The electrochemical corrosion test results showed that the corrosion resistance of the Cr–Ni–Fe alloy deposit electroplated at 20 A/dm² was better than that of the Cr–Ni–Fe alloy deposit obtained at 25 A/dm², despite having almost identical chemical compositions. These results were obtained by performing an electrochemical test and microstructure observations. - Highlights: • Cr–Ni–Fe alloy deposits were obtained in an eco-friendly Cr (III) bath. • Cr–Ni–Fe alloy deposits with different Cr, Ni and Fe contents were achieved. • Fe-rich and Cr-rich deposits were obtained by varying the plating current density. • Fe-rich deposits are crystalline, but Cr-rich deposits are amorphous. • An electrochemical corrosion test was conducted with Fe- and Cr-rich deposits