Well let's see now... In order to ground the Alu and copper parts, you'd use a copper wire, right?
You might crimp that wire to a steel pin, so that you can screw it into something, 'cause you'd be hard pressed to find copper connectors. And this would connect to the Aluminium, right?
I think you might induce a higher differential, which would accelerate the galvanic effect.
Let us know how it goes
