Alloy

The First Doctor cited molybdenum as an example of an alloy used in steel. (TV: The Sensorites)

Cupronickel was an alloy of copper and nickel. (PROSE: All I Want for Christmas)

Skaronium was so strong a metal that the Thals were forced to render it into an alloy to manipulate it. Their network of ionising towers was made of the Skaronium-alloy. (AUDIO: Return to Skaro)