请看:http://www.metallographic.com/Pourbaix-Cu.htm Corrosion Potentials: The Pourbaix diagram indicates that below a pH of 7 and at higher oxidation potential, copper can corrode. Since D.I. water typically has a pH value less then 6 and has an oxidation range in the vicinity of Cu(+2), thermodynamically copper can corrode. Simplified Pourbaix diagram for copper