how can i harden plated copper wire (wire that has been plated silver/gold)

[bvd1940]

Stretching it would harden it. The trick is to get the wire to stretch evenly all over. That is why drawing through a die would be a more certain method(if you have a die).

You can stretch as long of a piece you want without anything but a dead head & puller (much less involved) I have used a die and own one but much simpler & quicker to stretch it.
Just my 2 cents worth:whistle:

 

[4GSR]

There are a few grades of copper that can be aged at a certain temperature for a certain time and will add hardness. I would have to dig up my books and do some researching to identify those that can. Beryllium copper is one of them.