Effect of heat treatment on the highly corrosion-resistant Cu_(70)Ni_(27.7)Fe_(2.3) alloy

摘要

Minor Fe additions are widely added to enhance the corrosion resistance of cupronickel alloys. The present paper aims at optimizing the amounts of Fe in Cu_(70)(Ni,Fe)_(30) (at.%) alloys using a cluster-plus-glue-atom model for stable solid solutions. By this model, it is assumed that one Fe atom and 12 Ni atoms formed a Fe-centered and Ni-surrounded cube-octahedron cluster and the isolated FeNi_(12) clusters embedded in a Cu matrix. The stable solid solution alloy composition of Fe-modified Cu_(70)Ni_(30) alloy was described by a cluster formula [Fe_1Ni_(12)]Cu_(30.3) =Cu_(70)Ni_(27.7)Fe_(2.3) (at.%). The effect of homogenizing annealing treatment on the microstructure and corrosion resistance was also investigated by XRD, TEM and electrochemical corrosion measurements. The corrosion test indicates that the Cu_(70)Ni_(27.7)Fe_(2.3) alloy annealed at 800 ℃ for 5 h possesses the best corrosion resistance in 3.5% NaCl solution.