Influences of amorphous modification layer and Cu:Zr ratio on the corrosion behaviors of Cu–Zr binary alloys

Cu–Zr based alloys have long been a research focus due to their high amorphous forming ability and excellent comprehensive properties. However, whether it is the amorphous structure or Cu:Zr ratio that plays a major role in its corrosion resistance remains unclear. In this work, four types of Cu–Zr binary alloys are designed, and amorphous layers are constructed on the alloy surfaces via laser remelting. It is found that by applying laser scanning speeds of 40 mm/s and 60 mm/s, amorphous layers with the thickness of 80–100 μm are obtained on Cu 50 Zr 50 , Cu 52.5 Zr 47.5 , and Cu 55 Zr 45 alloys. The amorphous layer significantly improves the passivity and corrosion resistance of Cu–Zr alloy surfaces. Taking Cu 50 Zr 50 alloy as an example, the corrosion potential increases by 0.4 V, the breakdown potential enhances by 0.1 V, and the corrosion current density declines to 11.6 % (40 mm/s) and 36.6 % (60 mm/s) of that of the substrate. The passive films are composed of ZrO 2 and CuO, and the passive film on amorphous surface is thicker and has a lower density of point defects. It is confirmed that the contribution of amorphous layer to the improvement of corrosion resistance is more significant than that of Cu:Zr ratio. On the premise of forming an amorphous structure, higher Zr content will lead to stronger corrosion resistance. Our study can provide theoretical guidance for the composition design, surface structure tuning, and corrosion resistance regulation of Cu–Zr based alloys.