Can we use same tool to weld copper and aluminum?

No, it is important to use an FSW tool that is suitable for the material being welded.
Copper and aluminium react differently to heat during the welding process. If the temperature is too high, copper will tend to stick while aluminium will deform. We recommend choosing the right tool for a copper application or an aluminium application.
To ensure a quality weld for each application, Stirweld has designed FSW tools to suit the materials to be joined.