A method of casting an article includes forming a melt comprising copper, introducing manganese into the melt to produce a copper-manganese alloy, and casting the copper-manganese alloy in a mold to form the article. The carbon and oxygen contents of the copper-manganese alloy are controlled in order to control the formation of graphite, manganese carbide, and/or manganese oxide particles within the article. Copper-manganese alloys containing carbon are also provided, as well as articles made therefrom in cast or wrought form.