View Sample Alloy Digest Data Sheet (PDF)Since 1952, Alloy Digest has been the leading reference for materials property data on metals and alloys used throughout the world. Featuring graphs, charts and tables, these sheets give facts and figures on composition or characterization, physical and mechanical properties, heat treatment, and machinability.Copper Alloy No. 642 is a copper-aluminum-silicon alloy possessing high strength, good hot-working characteristics and good machinability. It has excellent resistance to corrosion in many environments.