On corrosion electrochemical behaviors of nanocrystalline bulk Ag-50Ni alloy in H_3PO_4 solution

Corrosion electrochemical behaviors of Ag-50Ni alloy with different grain sizes in H3PO4 and Na2SO4 solution were studied by using potentiodynamic polarization method and electrochemical impedance spectroscopy(EIS) technique.Research results show that EIS plots of the Ag-50Ni alloy are mainly composed of single capacitance loop,however,the EIS plots of the nano-sized Ag-50Ni alloys represent two capacitance loops when the concentration of H3PO4 is 0.0,0.1 and 0.5mol/L respectively,which illustrates that the corrosion processes are controlled by electrochemical reaction.With the increment of H3PO4 concentrations of media,their corrosion potentials of alloys move to the negative direction,corrosion current densities increase gradually,while transfer resistance decrease gradually.Corrosion current densities of nanocrystalline Ag-50Ni alloy increases and corrosion rates become fast as compared with the corresponding coarse grained Ag-50Ni alloy.Thus,corrosion resistances of nanocrystalline Ag-50Ni alloy decrease.