The Mechanism of Dealloying of Copper Solid Solutions and Intermetallic Phases

Potentiostatic experiments in 0.5 N NaCl at − 0.25 V SHE show that the kinetics of dealloying of copper base binary alloys fall in the order Cu ‐ Al > Cu ‐ Mn > Cu ‐ Zn > Cu ‐ Ni For the solutes Al and Zn, the kinetics of dealloying may be expressed by the relationship Log S e = KC s where S e is the excess solute dissolved and C s is the atom percent solute. K is related qualitatively to the reversible potential of the solute element. It is shown that dealloying cannot propagate into the alloys by diffusion of solute from the bulk to the surface. Instead, dealloying is maintained by solution intrusion under conditions where continuous solute paths exist in the alloy and where solute removal results in atomic rearrangement of the depleted alloy.