Abstract: The instant disclosure relates to ductile iron alloy compositions and articles that can maintain desired microstructural and mechanical properties even when cast to make thin-wall samples. Particularly, the compositions herein may maintain hardness and ductility and minimize carbide formation even when cast in samples as thin as about 1 mm to about 6 mm. In particular, the instant disclosure relates to a cast iron alloy composition including nodular or spheroidal graphite domains comprising an iron content of at least about 90% by weight, a remaining alloy content of less than about 10% by weight, about 0.65% to about 0.85% by weight copper, about 3.6% to about 4.2% by weight silicon, and about 3.4% to about 3.8% by weight carbon.