Diffusion Behavior and Kinetics of the Iron–Nickel Interface During Annealing Treatment

The notorious corrosion resistance of carbon steel significantly limits its scope of application. In this study, a strategy involving electrodeposited nickel followed by annealing was proposed to improve the corrosion resistance of materials. The effects of annealing on the microstructure of nickel-plated steel were investigated by scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). The results reveal annealing induces Fe-Ni alloy layer formation at the plating–substrate interface, with thicknesses ranging from 2.2 μm to 4.8 μm as the temperature increases from 650 °C to 800 °C and the duration extends from 1 min to 5 min. Additionally, a diffusion kinetics model based on Fick’s second law was established to describe the diffusion process of nickel atoms in the iron matrix. The diffusion coefficients of nickel atoms were determined to be in the range of 4.4 × 10−16 m²·s⁻¹ to 1.26 × 10−15 m²·s⁻¹ under the tested conditions. This model provides a theoretical framework for optimizing annealing treatments to enhance the performance of nickel-coated carbon steel components.