Effect of Trace RE on Corrosion Behavior of Ag-Cu-Ni Alloys

Abstract

The corrosion performance of Ag-Cu-Ni-RE alloys in Na2S has been studied in order to assess the influence of rare earth (lanthanum and cerium) on the Ag-Cu-Ni alloys. Optical microscopy has been used to characterize the microstructures of the samples prior to the electrochemical tests. SEM, EDS and XRD have been used to observe the corrosion morphologies and chemical compositions of the samples. The electrochemical tests has been carried out at room temperature in 0.5, 1and 2% (wt. %) Na2S. The results reveal that the Ag-Cu-Ni-RE alloys exhibit improved corrosion resistance, as well as fine and uniform microstructures. Moreover, surface layers forming on Ag-Cu-Ni-RE alloys exhibit improved protective properties compared to the film growing on the Ag-Cu-Ni alloy. Here, it is also found that when comparing to the dilute Na2S solution conditions, there would be a little decrease of the corrosion rate in 2wt. %Na2S solution. In addition, Ag-Cu-Ni-La-Ce alloy generally exhibits the best corrosion resistance.

Study on Microstructure and Corrosion Behavior of Ag-Cu-Zn-Ni Alloys

“…The corrosion process of the samples is actually an oxygen-consuming corrosion in Na 2 S solutions. By referring to literature [10], as shown in Table 3 is the calculating gibbs free energy ( G ∆ ) of corrosion products at room temperature, detected based on XRD. The gibbs free energy can be used to estimate if some substance could be produced steady in aqueous solution or not.…”