Improved Corrosion Resistance of Ni‐Based Alloys by B‐Induced Passivation Behavior

Nickel‐based alloys exhibit excellent mechanical properties, but the corrosion resistance when exposed to NaCl solution needs to be improved, thus limiting their widespread applications. In this study, it is demonstrated that a moderate addition of boron, specifically 3.5 wt%, can effectively enhance both the tribological properties and corrosion resistance of Ni‐based alloys. The microstructures evolution and corrosion mechanism of Ni–Cu–xB (0–5 wt%) alloys have been comprehensively investigated through the experimental characterization and phase diagram calculations. The improvements in corrosion resistance can be primarily attributed to the formation of continuous and dense passivation films. Additionally, the dissolved B fixes chloride ions to hinder the breakdown of passivation films. However, an excessive addition of boron can have a detrimental effect on corrosion resistance. While improving the formation of dense passivation films, the excessive presence of boron also prompts the precipitation of a Cu‐rich phase that is highly susceptible to corrosion by chloride ions, thereby exacerbating the corrosion process in the alloy.