Selective etching of Cu--Be--Ni--Zr alloy by potentiostatic method

The anodic behavior and metallographic etching of a quaternary Cu--Be--Ni--Zr alloy in 65 percent phosphoric and 50 percent citric acid have been studied by means of the potentiostatic method. The results show a basically different behavior of this alloy in two electrolytes. A passivation film is formed in phosphoric acid in the potential range -650 to -450 mV (SSE), while in citric acid the anodic dissolution is continuously accelerated with increasing potential. Consequently, revealing the microstructure in two electrolytes occurs at different potentials and etching times. The citric acid was also found to be very efficient for selective anodic dissolution of Cu-matrix and isolation of intermetallic phase