Corrosive properties of CuNi2SiCr fabricated through directed energy deposition on a nickel-aluminum bronze substrate

Abstract

In this study, CuNi2SiCr powders were deposited on nickel-aluminum bronze (NAB) substrates through directed energy deposition (DED) and the corrosive resistance properties of the deposited CuNi2SiCr were evaluated through comparisons to the substrate. Metallographic observations revealed that the microstructure of the deposited layers was α-Cu, which is characterized by low strength and hardness, and high toughness. The microstructure of the NAB substrate exhibited higher hardness and strength than the deposited CuNi2SiCr because the substrate was composed of a typical α + β solid solution and different intermetallic κ phases. The electrochemical corrosion test demonstrated that the corrosion stability of the CuNi2SiCr-deposited was slightly better than that of the NAB substrate. Furthermore, the corrosion current density of NAB is slightly greater than that of the deposited CuNi2SiCr based on the existence of multiple phases forming a corrosion galvanic cell. The results of the cavitation erosion test revealed that the wear rate of the deposited material under the mechanical impact of bubbles is significantly greater than that of the substrate. The results of immersion test demonstrated that the corrosive resistance of NAB is significantly greater than that of CuNi2SiCr because a dense Al2O3 oxide film is formed on its surface. This study provides new concepts for the application of DED technology and CuNi2SiCr alloy. However, experimental results also demonstrate that the corrosion resistance of CuNi2SiCr alloy is lower than that of NAB and its performance must be further improved for application it in a marine-like working environment.