The Preparation And The Anticorrosion Properties Of The Zr-Cu-Ni-Al Metallic Glasses/crystalline Composite Coatings By Laser Cladding

Corrosion is one of the most common failure modes of metallic materials.Improving the corrosion resistance of metallic materials is of great significance.Amorphous alloys have excellent corrosion resistance due to their unique short range ordered and long range disordered structures,it is free from defects such as vacancies,dislocations and grain boundaries in common crystal materials.Laser cladding technology can effectively avoid the size limit of amorphous alloy and improve the corrosion resistance of metal substrate,but the understanding of the corrosion behavior of amorphous/crystalline composite coating prepared by laser cladding is not deep enough,which needs to be further studied.In this paper,Zr_50.7Cu₂₈Ni₉Al_12.3 mixed metal powders was selected as cladding materials to prepare Zr-Cu-Ni-Al amorphous/crystalline composite coating under different laser power and scanning speed,and the corrosion resistance of the coating in NaCl medium was studied.It was found that the coating has good metallurgical bonding with the substrate and the coating structure is compact without obvious defects.The coating is mainly composed of amorphous phase,metal compounds such as CuZr₂,Cu₁₀Zr₇ and Ni₁₀Zr₇,and metal oxides such as Al₂O₃.The content of amorphous phase increases first and then decreases with the increase of laser power and scanning rate.Before remelting,when the laser power was 1000 W and the scanning rate was 1 m/min,the coating had the best corrosion resistance,the corrosion potential was-0.376 V,and the current density was 9.54×10^-77 A/cm².Laser remelting was also carried out on the prepared composite coatings.The variation of the microstructure and corrosion resistance of the laser remelting coatings with different laser power and scanning speed were studied.It was found that the amorphous phase content of the coating increased significantly after laser remelting,and the amorphous phase content of the coating increased first and then decreased with the increase of remelting laser power and scanning speed.When the remelting power is 1000W and the scanning speed is 7 m/min,the corrosion resistance of the remelting coating is the best.At this time,the corrosion potential is-0.257 V and the corrosion current density is 3.74×10^-9 A/cm²,indicating that the corrosion resistance of the coating can be effectively improved by laser remelting.