The wire used in transformers is usually made of copper or aluminum. Copper wire is the most widely used material due to its excellent electrical conductivity and thermal conductivity properties. However, aluminum wire is also used in some transformers, especially larger power distribution transformers, because it is lighter and less expensive than copper.
Transformers are mainly made of steel or rolled iron cores and copper or aluminum windings. The core material is chosen for its magnetic properties, such as high permeability and low hysteresis loss, which enable it to efficiently transfer magnetic flux between the primary and secondary windings. Copper or aluminum wire is wound around the core to form the primary and secondary coils, depending on the transformer design and intended application.
In summary, while the core of a transformer is usually made of steel or iron, the wire used for the windings can be made of copper or aluminum, with copper being more common due to its higher electrical conductivity.